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  PS02-D5-PM2-P-009 (PS02-A009)
 
A Systematic Survey of Transient Landforms at the South Pole of Mars-A Case Study of the Cavi Angusti Area
Jingyan HAO1#+, Stephan VAN GASSELT2
1 Freie Universität Berlin, Germany, 2 University of Seoul, South Korea
#Corresponding author: bella@zedat.fu-berlin.de +Presenter

For over forty years, a plethora of instruments employed on orbiting spacecraft has been acquiring remotely sensed datasets of the surface of Mars. Due to usually polar orbit geometries, data coverage is most dense across the polar area. At these locations, 100s of images obtained by different sensors cover the same spot at different seasons of the year, which provides an outstanding opportunity to study landforms in detail and across different seasons.

Such an asset, however, comes at the price of having to find strategies to exploit the wealth of data efficiently in order to establish a seasonal context, to analyze interdependences between landforms, and to reconstruct the evolution of features on the surface that were formed by an interplay of deposition and sublimation of CO2 and H2O ices. Although understanding of the composition and seasonal development of the Martian south polar area have been greatly promoted by the wealth of orbital data, a systematic survey of seasonal changes is still missing for many of these characteristic landforms. 

For this study, we here chose the prominent and morphologically diverse Cavi Angusti region near the Martian south pole.  It is located in the polar–layered deposits (PLD) and exhibits a high diversity of different geological and geomorphological features. We provide a detailed distribution mapping of landform types and perform a systematic analysis of these landforms within their seasonal context.  We have been using high-resolution image and terrain–model data obtained from MRO CTX, MGS MOC, MO THEMIS, and MEx HRSC sensors at a scale of 5-15 m per pixel, and combine these datasets with information derived from DIVINER and TES in order to derive environmental parameters helping to reconstruct the seasonal landform evolution.

  PS02-D5-PM2-P-010 (PS02-A011)
 
Initial Results of Venus Orbiter Akatsuki
Takeshi IMAMURA#+
The University of Tokyo, Japan
#Corresponding author: t_imamura@edu.k.u-tokyo.ac.jp +Presenter

Japanese Venus orbiter Akatsuki aims to elucidate the mechanism of atmospheric circulation and cloud formation of Venus. The orbit insertion maneuver conducted in 2010 was not successful, and after the 5-years of additional interplanetary cruise, the spacecraft entered a Venus-encircling orbit in December 2015. The new orbit is much larger than the original. We are developing a long-term observation plan for this new orbit. 

  PS04-D5-PM2-P-012 (PS04-A001)
 
An Induced Global Magnetic Field Looping Around the Magnetotail of Venus
Lihui CHAI1#+, Yong WEI1, Weixing WAN1, Tielong ZHANG2,3, Markus FRAENZ4, Eduard DUBININ4, Zhaojin RONG1, Hui ZHANG1, Jun ZHONG1, Xiuhong HAN1, Stas BARABASH5
1 Chinese Academy of Sciences, China, 2 Austrian Academy of Sciences, Austria, 3 University of Science and Technology of China, China, 4 Max-Planck-Insitute for Solar System Research, Germany, 5 Swedish Institute of Space Physics, Sweden
#Corresponding author: chailihui@mail.iggcas.ac.cn +Presenter

Venus serves as the prototype of solar wind interaction with unmagnetized planetary bodies with atmospheres. It has no intrinsic dipole or crustal magnetic field, the only magnetic field is believed to be formed by the draped interplanetary magnetic field (IMF). However, the large-scale magnetic field observed over the north polar region of Venus has a bias in the dawnward direction and seemingly unresponsive to the IMF's direction. Here we show that besides the draped field, there is a second type of induced global magnetic field at Venus, and the dawnward field is only a part of it. This global field has a distribution in a cylindrical shell around the magnetotail and a counterclockwise direction looking from the planetary tail toward the Sun, which demonstrates that there are two currents flowing out and in of the planet along the inner and outer boundaries of the looping field, respectively.

  PS04-D5-PM2-P-013 (PS04-A006)
 
Solar Cycle Variation of the Venus Magnetic Barrier
Tielong ZHANG1,2#+, Wolfgang BAUMJOHANN1, Sudong XIAO2
1 Austrian Academy of Sciences, Austria, 2 University of Science and Technology of China, China
#Corresponding author: tielong.zhang@oeaw.ac.at +Presenter

Although there is no intrinsic magnetic field at Venus, the convected interplanetary magnetic field piles up to form an induced magnetosphere around the planetary ionosphere.  The induced magnetosphere consists of regions near the planet and its wake for which the magnetic pressure dominates all other pressure contributions. Previous PVO investigations show that the magnetic barrier, the part of the induced magnetosphere in the dayside inner magnetosheath, can act as an effective obstacle to the solar wind during the solar maximum. Initial Venus Express observations indicate that the magnetic barrier can stop the solar wind even during the solar minimum. In this study, we perform comprehensive statistical study of the magnetic barrier during nearly a whole solar cycle using Venus Express magnetic data.  We show that the general magnetic barrier configuration is controlled by the solar activities and the interplanetary magnetic field orientation.

  PS04-D5-PM2-P-014 (PS04-A008)
 
Nightside Ionosphere Contributed by Day-To-Night Transport: A Comparative Study of Mars, Venus and Titan
Jun CUI1,2#+
1 Chinese Academy of Sciences, China, 2 Macau University of Science and Technology, China
#Corresponding author: cuij@nao.cas.cn +Presenter

Any Solar System body with a permanent atmosphere also possesses a well-defined ionosphere. While it is well known that a dayside ionosphere is produced by solar EUV/X-ray ionization, the pathway leading to the formation of a nightside ionosphere is more variable, with charged particle precipitation and day-to-night transport considered as two most important mechanisms. Possible observations supporting the transport scenario include the variations of the ionospheric structure (in terms of the peak plasma density and/or the total plasma content) with solar zenith angle, local time, external plasma pressure, as well as ambient magnetic field topology, among others. In this presentation, I will show evidences for the formation of nightside ionosphere via transport on three terrestrial planets: Mars, Venus and Titan. Existing evidences indicate that the transport scenario is important for establishing the nightside ionosphere for ~ 6×103 s after terminator crossing on Mars, the portion of the nigthside ionosphere with long-lived constituents on Titan, as well as the entire nightside ionosphere on Venus.

  PS04-D5-PM2-P-015 (PS04-A009)
 
MESSENGER Observations of Flux Ropes and Reconnection Fronts: Locations of the Near Tail Reconnection Site at Mercury
Weijie SUN1#+, Suiyan FU1, James SLAVIN2, Jim RAINES2, Gangkai POH2
1 Peking University, China, 2 University of Michigan, United States
#Corresponding author: sunweijie.rain@gmail.com +Presenter

A statistical study of flux ropes and reconnection fronts (also called dipolarization fronts) base on MESSENGER magnetic field and plasma observations and its implication for the distribution of magnetic reconnection site in the Mercury’s magnetotail has been performed in this research. We have surveyed the plasma sheet crossings at Mercury during three hot seasons of MESSENGER for flux ropes and reconnection fronts, which are believed to be highly related with magnetic reconnection. During the three hot season orbits. MESSENGER crossed the plasma sheet were mostly at a distance between - 2 RM and -3 RM, which is the region of previous determined location of Near Mercury Neutral Line. Thirty-nine flux ropes and 92 reconnection fronts were identified. The occurrence frequency distribution of flux ropes and reconnection fronts in the plasma sheet shows a clear dawn-dusk asymmetry with higher occurrence frequency on the dawn side than the dusk side. This suggests that magnetic reconnection in Mercury’s magnetotail happens more frequently on the dawn side than dusk side plasma sheet. This is opposite to the observations in Earth’s magnetotail showing magnetic reconnection more frequently occurs on the dusk side than the dawn side plasma sheet. We have further studied the thickness distribution of plasma sheet based on plasma β. The distribution of thin plasma sheet (< 0.2 RM and < 0.1 RM) shows a peak occurrence rate in the midnight region, and does not show clear dawn-dusk asymmetry, so that plasma sheet thickness cannot explain the high occurrence frequency of magnetic reconnection on the dawn side. Therefore, the reasons that cause magnetic reconnection to preferentially occur on the dusk side of the magnetotail at Mercury require further study.

  PS04-D5-PM2-P-016 (PS04-A013)
 
Hemispheric Asymmetry in the Near-Venusian Magnetotail During Solar Maximum
Sudong XIAO1#+, Tielong ZHANG1,2, Wolfgang BAUMJOHANN2
1 University of Science and Technology of China, China, 2 Austrian Academy of Sciences, Austria
#Corresponding author: xiaosd@mail.ustc.edu.cn +Presenter

It is now known that the near Venusian magnetotail is very dynamic and also prone to magnetic reconnection. Especially, it is found that the atmospheric escape is controlled by the magnetotail configuration. It is therefore essential to study the magnetic field pattern in the Venusian magnetotail. During solar minimum, the near-Venusian magnetotail exhibits a hemispheric asymmetry in the cross tail field distribution [Zhang et al., 2010]. It implies that the magnetic field lines in the –E hemisphere are wrapped more tightly around Venus than in the +E hemisphere. Therefore, a strong field reversal region occurs in the magnetotail, which is prone to the magnetic reconnection [Zhang et al., 2012]. Since the Venus magnetotail is formed due to the solar wind interaction with the ionosphere and the ionosphere is modulated by the solar activity, it is interesting to study the solar cycle dependence of the induced magnetosphere. Here we statistically examine the Venus Express magnetotail data during solar maximum. We find that the magnetic field configuration asymmetry in Venus magnetotail is very much similar to that during solar minimum. The hemispheric asymmetry in the magnetotail persists through the whole solar cycle and magnetic reconnection in the near-Venusian magnetotail might occur during solar minimum as well as solar maximum conditions.

  PS04-D5-PM2-P-017 (PS04-A015)
 
Ionospheric Flux Ropes Observed by Venus Express Magnetometer
Yuanqiang CHEN1+, Sudong XIAO1#, Tielong ZHANG1,2
1 University of Science and Technology of China, China, 2 Austrian Academy of Sciences, Austria
#Corresponding author: xiaosd@mail.ustc.edu.cn +Presenter

Within the Venus ionosphere, discrete excursions of magnetic field can be observed, rising from a background of a few nT to many tens of nT, and this structure is described as “flux ropes”. Many works focusing on magnetic flux ropes in the Venus ionosphere had been done by PVO observations, examining the models, global characteristics and probably origins of flux ropes. Venus Express (VEX), known as the first European mission to planet Venus, has the improved instrumentation onboard, which means higher time and spatial resolution compare with the PVO. Especially, VEX owns a different, steady orbit with a lower perigee than PVO and provides better data coverage in studying regions, like the terminator. Thus it makes a complement to PVO project. In this paper, by using the Venus Express magnetic field data, we first examine several flux rope traversals separately to review its properties corresponding to the models used by Elphic and Russell [1983]; after that, we make a statistical work about the distribution of the flux ropes along altitude and discuss its spatial occurrence and scale size and make a brief comparison with the prior work of Elphic and Russell [1983].

  PS04-D5-PM2-P-018 (PS04-A016)
 
Factors Controlling the Location of the Ionopause and Photoelectron Boundary on Mars
Xiuhong HAN#+
Chinese Academy of Sciences, China
#Corresponding author: hanxiuhong@mail.iggcas.ac.cn +Presenter

The ionopause and photoelectron boundary (PEB) are two different methods that are used to recognize the upper boundary of the Martian ionosphere, or the interface between the Martian ionosphere and solar wind. The location of the ionopause and PEB determined from Mars Express during 2006-2014 is analyzed under different conditions of solar wind, solar EUV and crustal fields to determine those factors that control the size of the Martian ionopause and PEB.

  PS04-D5-PM2-P-019 (PS04-A021)
 
Foreshock ULF Waves at Mars: Maven Observations
Lican SHAN1#+, Christian MAZELLE2, Karim MEZIANE3, Suranga RUHUNUSIRI4, Jared ESPLEY5, Jasper HALEKAS4, Jack CONNERNEY5, James MCFADDEN6, David MITCHELL6, Davin LARSON6, David A. BRAIN7, Bruce JAKOSKY7, Yasong GE1, Aimin DU1
1 Chinese Academy of Sciences, China, 2 Paul Sabatier University, France, 3 University of New Brunswick, Canada, 4 University of Iowa, United States, 5 NASA Goddard Space Flight Center, United States, 6 University of California, Berkeley, United States, 7 University of Colorado Boulder, United States
#Corresponding author: lcshan@mail.iggcas.ac.cn +Presenter

Foreshock ULF waves constitute a significant physical phenomenon of the plasma environment for terrestrial planets. The occurrence of these ULF waves, associated with backstreaming ions reflected and accelerated atthe bow shock, implies specific conditions and properties of the shock and its foreshock. For an unmagnetized planet like Venus or Mars, the part of the ion foreshock region where such ULF waves can be excited is smaller both in terms of planetary radius and absolute size than for a magnetized planet like the Earth where the bow shock is located much further away from the planet. Previous studies showed that quasi-monochromatic foreshock ULF waves were observed at Venus, but there was no relevant observation at Mars [where only pickup-ion related waves observed at the cyclotron frequency had been reported in the same frequency range]. Using measurements from MAVEN, we report clear observations of this type of ULF waves in the smaller Martian foreshock. We show from different case studies that the peak frequency of the wave case in spacecraft frame is too far from the local ion cyclotron frequency to be associated with local pickup ions taking into account the Doppler shifted frequency from a cyclotron resonance, the obliquity of the mode, resonance broadening and experimental uncertainties. Their properties fit very well with waves driven unstable by foreshock backstreaming ion population for which the parallel velocity is larger than at least twice Vsw to match the cyclotron resonance condition. The propagation angle is usually less than 30 degrees from ambient interplanetary magnetic field. The waves also display elliptical and left-hand polarizations with respect to the field in the spacecraft frame. Moreover their occurrence is controlled by rotations of the IMF. It is clear for these cases that foreshock ions are simultaneous present for the ULF wave intervals. Such observation is important in order to discriminate with the already well-reported pickup ion (protons) waves associated with exospheric hydrogen in order to quantitatively use the later to study seasonal variations of the hydrogen corona. The comparison between foreshock ULF waves at Venus and Mars is also discussed.

  PS04-D5-PM2-P-020 (PS04-A025)
 
The Morphology of Magnetic Field Structure in Mercury’s Magnetotail: Messenger Observations
Zhaojin RONG1, yuan DING2#+, Jun ZHONG1, Yong WEI1, Lihui CHAI1, Weixing WAN1
1 Chinese Academy of Sciences, China, 2 Institute of Geology and Geophysics,Chinese and Academy and Sciences, China
#Corresponding author: dingyuan@mail.iggcas.ac.cn +Presenter

The knowledge of morphology of magnetic field of Mercury’s magnetotail is essential to explore the dynamics of Mercury’s magnetotail. In this study, we use the magnetic field data measured by MESSENGER during its orbital insertion of Mercury from 2011 to 2014 to investigate the global magnetic field morphology of Mercury’s magnetotail in the downtail 0~ 3 RM (RM = 2440 km, Mercury's radius). It is found that, the magnetic field structure beyond ~1.5 RM downtail is stretched significantly forming the tail field. The half-width of magnetotail in north-south direction is about 2.8 RM with typical lobe field ~50 nT, while the transverse width in equatorial plane is about 4 RM. Thus, the magnetotail is seemed to be elongated along north-south direction. The tail current sheet is basically on the magnetic equatorial plane. The magnetic field in lobe is flaring, which is nearly dawn-dusk symmetric about the midnight. The fitting of Harris sheet model is adopted to estimate the average thickness of the magnetotail current sheet and the current density at the sheet center for the inner tail (-1.5>X>-2.0 RM) and outer tail (-2.0>X>-2.5RM) respectively. We find that the average half-thickness of current sheet is thin around midnight region (~80 km for inner tail; ~200 km for outer tail) while the current density is stronger (~35 nA/m2 for inner tail; ~65 nA/m2 for outer tail), but the half-thickness increases towards both flanks (~350 km for inner tail; ~450 km for outer tail) with decreased current density (~20 nA/m2 for both inner and outer tail). The distributions of half-thickness and current density are of nearly dawn-dusk symmetry, which shows distinct discrepancy with the dawn-dusk symmetry of Earth’s magnetotail. The possible reasons are discussed.

  PS04-D5-PM2-P-021 (PS04-A028)
 
Compressibility of Mercury's Dayside Magnetosphere
Jun ZHONG1#+, Weixing WAN1, Yong WEI1, James SLAVIN2, Jim RAINES2, Zhaojin RONG1, Lihui CHAI1, Xiuhong HAN1, Ruilin LIN1
1 Chinese Academy of Sciences, China, 2 University of Michigan, United States
#Corresponding author: j.zhong@mail.iggcas.ac.cn +Presenter

Mercury's comparatively weak intrinsic magnetic field, together with the strong solar wind forcing in the inner heliosphere, creates a small and highly dynamic magnetosphere. Unlike other planets in the solar system, Mercury is experiencing significant variations of solar wind forcing along its large eccentric orbit.With 12 Mercury years of data from MESSENGER, we demonstrate that Mercury's distance from the Sun has a great effect on the size of the dayside magnetosphere that is much larger than the temporal variations. The mean solar wind standoff distance was found to be about 0.27 Mercury radii (RM) closer to the Mercury at perihelion than at aphelion. At perihelion the subsolar magnetopause can be compressed below 1.2 RM of ~2.5% of the time. The relationship between the average magnetopause standoff distance and heliocentric distance suggests that on average the effects of the erosion process appears to counter balance those of induction in Mercury's interior at perihelion. However, at aphelion, where solar wind pressure is lower and Alfvénic Mach number is higher, the effects of induction appear dominant.

  PS05-D5-PM2-P-015 (PS05-A002)
 
Solar Wind Ion (H+ /He++) Reflection Over Lunar Magnetic Anomalies
Daiba KATO1#+, Yoshifumi SAITO2, Shoichiro YOKOTA2, Masaki N. NISHINO3
1 The University of Tokyo, Japan, 2 Japan Aerospace Exploration Agency, Japan, 3 Nagoya University, Japan
#Corresponding author: daiba@stp.isas.jaxa.jp +Presenter

The Moon is located outside the Earth’s magnetosphere at a rate of about 80% except for the full moon period. The solar wind can directly interact with the lunar surface since the Moon has neither thick atmosphere nor global magnetic field. The solar wind consists of H+ as a major component, several percent of He++ as a second major component, and a small amount of heavier ions. It is known that the flux of the magnetically reflected solar wind ions is about ten percent of the incident solar wind ion flux. Although ion mass is an important parameter of the magnetic reflection process, mass dependence of the reflected ions is not known at all.

The purpose of this study is to understand the ion reflection process over lunar magnetic anomalies. We have analyzed the data obtained by low energy charged particle analyzers MAP-PACE and magnetometer MAP-LMAG on Kaguya. As a result of the analysis of the reflected ions, we have found that solar wind H+ and He++ are both reflected by magnetic anomalies. In particular, quantitative observation of reflected He++ is made for the first time. Although the reflected ions have higher temperature than the incident solar wind ions, the reflected He++ ions have lower velocity and flux than the reflected H+ ions. Since high energy ions have larger larmor radius, the high energy ions can penetrate deeper into the magnetic anomalies than the low energy ions. Therefore, the amount of the solar wind ions that impact the lunar surface depends on the ion species.

Lunar magnetic anomaly is one of the examples that have the smallest scale in the solar system. The knowledge acquired by this study is useful not only to understand lunar plasma environment, but also to understand plasma environment around various astronomical bodies.

  PS05-D5-PM2-P-016 (PS05-A003)
 
Deep Nightside Photoelectron Observations by Maven Swea
Shaosui XU1#+, David MITCHELL1, Michael LIEMOHN2, Chuanfei DONG3, Stephan W BOUGHER4, Matthew FILLINGIM1, James MCFADDEN1, Christian MAZELLE5, J. E. P. CONNERNEY6, Bruce JAKOSKY7
1 University of California, Berkeley, United States, 2 University of Michigan Ann Arbor, United States, 3 Princeton Plasma Physics Laboratory, United States, 4 University of Michigan, United States, 5 Paul Sabatier University, France, 6 NASA Goddard Space Flight Center, United States, 7 University of Colorado Boulder, United States
#Corresponding author: shaosui.xu@ssl.berkeley.edu +Presenter

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has a periapsis of altitudes as low as ~150 km. During an orbit on January 5th, 2015 (Orbit 520), the Solar Wind Electron Analyzer (SWEA) instrument observed photoelectrons at altitudes below 200 km, SZA > 120 degrees and high northern latitudes (>60 degrees). Such observations imply that large cross-terminator closed magnetic field loops exist that extend thousands of kilometers to deep nightside, even over the weak northern crustal source regions, which was thought to be dominated by draped interplanetary magnetic fields (IMF). Such a day-night magnetic connectivity also brings a particle and energy source to the deep nightside. Based on our estimations with both a simple calculation and the SuperThermal Electron Transport (STET) model, this study shows that the precipitating photoelectrons into the nightside are able to support the observed O2+ density by the the Suprathermal and Thermal Ion Composition (STATIC) instrument below 200 km. This finding indicates another channel for Martian energy redistribution to the deep nightside, and consequently localized ionosphere patches and potentially aurora.

  PS05-D5-PM2-P-017 (PS05-A005)
 
Bepi Colombo MPO-MMO Coordinated Observations
Anna MILILLO1#, Go MURAKAMI2+, Joe ZENDER3, Sara LA FUENTE3, Masaki FUJIMOTO2, Johannes BENKHOFF3, Mauro CASALE4, Jonathan MCAULIFFE3, Fernando PEREZ LOPEZ3
1 National Institute for Astrophysics(INAF), Italy, 2 Japan Aerospace Exploration Agency, Japan, 3 European Space Agency, Spain, 4 European Space Astronomy Centre, Spain
#Corresponding author: anna.milillo@iaps.inaf.it +Presenter

Using simultaneous two-point measurements from two satellites, ESA-JAXA BepiColombo mission will offer an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with solar radiation and interplanetary dust. Many scientific instruments onboard the two spacecraft will be completely, or partially, devoted to studying the close environment of the Mercury planet as well as the complex processes that govern it. The specific orbits of the two spacecraft and the comprehensive scientific payload will make this mission a great improvement with respect to the successful mission MESSENGER that ended in 2015. Coordinated measurements by different onboard instruments will permit a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone. These joint observations are of key importance because many phenomena in Mercury’s environment are temporarily and spatially varying. Examples of possible coordinated observations are described in the following by analyzing the required geometrical conditions, pointing, modes, timing and interfaces between the two European (SGS) and Japanese (SSOC) science ground segments.

  PS05-D5-PM2-P-018 (PS05-A011)
 
A Predictor-Corrector Schema Based Upon Boris Schema for the Integration of the Equations of Motion of Charged Particles : Application to Mercury’s Magnetosphere
Gerard CHANTEUR#+
Ecole Polytechnique, France
#Corresponding author: gerard.chanteur@lpp.polytechnique.fr +Presenter

A lot of numerical schemes are available for integrating the equations of motion of a charged particle in an electromagnetic field. The schema proposed by Boris (1970) is one of the most remarkable due to its simplicity and accuracy and hence is widely used in numerical plasma physics. Although being not a leap-frog schema due to the dependence of the electromagnetic force upon the velocity, it has a structure reminiscent of the leap-frog which imposes to stop and restart the integration in order to change the time step. Hence the original Boris’ schema does not allow a continuous adaptation of the time step. Changing the time step during self-consistent numerical simulations would be difficult, if not practically impossible, but it may be of interest for test particle simulations. We present a predictor-corrector schema making use of the acceleration substep of Boris’ algorithm which allows to vary continuously the time step. We have also designed a procedure for the automatic control of the time step. Applications to the motion of charged particles in the magnetosphere of Mercury will be presented.

Reference

1. Boris, J.P., ''Relativistic Plasma Simulation - Optimization of a hybrid code'', in Proceedings of the 4th Conference on Numerical Simulation of Plasmas, pp 3-67, NRL, Washington, Nov. 1970.

Acknowledgement The author is indebted to Kyoto University for an invited stay of three months during spring 2015 at the Research Institute for a Sustainable Humanosphere (RISH) where this work has been initiated. 

  PS05-D5-PM2-P-019 (PS05-A013)
 
The Magnetosphere of the Earth Under Sub-Alfvénic Solar Wind Conditions
Emmanuel CHANÉ#+
University of Leuven, Belgium
#Corresponding author: Emmanuel.Chane@wis.kuleuven.be +Presenter

On the 24th and 25th of May 2002, the solar wind was sub-Alfvénic for several intervals that lasted as long as four hours (the Alfvén Mach number was as low as 0.4). This sub-Alfvénic solar wind intervals were caused by an unusual solar wind density: as low as 0.04 proton per cubic centimetres. Consequently, the magnetosphere changed dramatically: the bow-shock disappeared and two Alfvén wings formed on the flanks of the magnetosphere. Alfvén wings are long tubular structures where the incoming plasma is decelerated and where the magnetic field direction changes. We estimated that the wings were 600 Re during this event and that the solar wind deceleration was 30% in one wing and 60% in the other wing. The Geotail spacecraft crossed one of these wings multiple time. Alfvén wings have been observed and studied in great details in the giant magnetospheres where they are common (e.g. at Io, Europa, Enceladus), but were not expected to be found at Earth.

We have also performed global MHD simulations that confirm that Alfvén wings are present at Earth during such unexpected solar wind conditions. In the simulations, we see that the closed magnetic field line region becomes very symmetric and expends extends up to 20 Re on the day-side as well as on the night side. The open field line region, on the other hand, becomes highly asymmetric: the field lines emanating from the northern hemisphere all point in the direction of the dawn Alfvén wing (around 8:00LT), while the field lines from the southern hemisphere all point in the other wing (around 22:00LT).

We also found that sub-Alfvénic solar wind intervals at Earth, which lasted for more than one hour and that were caused by unusually low solar wind density are not unheard of. Since 1963 such events occurred 16 times (even though, for most of these events, the Mach number was not as low as in May 2002). If we take into consideration the uneven data coverage, we can calculate that these events occur, on average, every 2.2 years.

  PS05-D5-PM2-P-020 (PS05-A015)
 
Science Operations Plan of BepiColombo MMO
Go MURAKAMI#+, Masaki FUJIMOTO
Japan Aerospace Exploration Agency, Japan
#Corresponding author: go@stp.isas.jaxa.jp +Presenter

BepiColombo is an ESA-JAXA joint mission to Mercury with the aim to understand the process of planetary formation and evolution as well as to understand similarities and differences between the magnetospheres of Mercury and Earth. The baseline mission consists of two spacecraft, i.e. the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The two orbiters will be launched in 2017 by an Ariane-5 and arrive at Mercury in 2024. JAXA is responsible for the development and operations of MMO, while ESA is responsible for the development and operations of MPO as well as the launch, transport, and the insertion of two spacecraft into their dedicated orbits. Being a spin-stabilized spacecraft, MMO has much less constraint for plasma observations and is expected to extract essential elements of space plasma physics that become visible in the Hermean environment. However, MMO has large constraints on science operations, such as thermal issue and limited telemetry rate. Due to the thermal issue each science instrument cannot always be turned on. In addition, due to the low telemetry rate in average, only a part (~20-30%) of science mission data with high resolution can be downlinked. Therefore, in order to maximize the scientific results and outcomes to be achieved by MMO, we must optimize the science observation and downlink plans in detail. In this paper, we summarize the basic plans and strategies of MMO science operations.

  PS05-D5-PM2-P-021 (PS05-A016)
 
BepiColombo Mercury Planetary Orbiter (MPO) Science Operations
Sara LA FUENTE1#+, Fernando PEREZ LOPEZ1, Santa MARTINEZ1, Jonathan MCAULIFFE1, Mauro CASALE1, Johannes BENKHOFF1, Joe ZENDER1, Go MURAKAMI2
1 European Space Agency, Spain, 2 Japan Aerospace Exploration Agency, Japan
#Corresponding author: sfuente@sciops.esa.int +Presenter

BepiColombo is an Interdisciplinary Cornerstone ESA-JAXA Mission to Mercury, with two orbiters dedicated to study of the planet and its magnetosphere.

The MPO, ESA's scientific contribution to the mission, is a three-axis-stabilized, nadir-pointing spacecraft which will be placed in a polar orbit, providing excellent spatial resolution over the entire planet surface. The MPO’s scientific payload comprises 11 instrument packages consisting of 17 units.

The MPO science operations planning process is a multi-cycle process carried-out by the SGS located at the European Space Astronomy Centre (ESAC), in conjunction with the instrument teams. The process will always consider the complete nominal mission duration, such that the contribution of the scheduled observations to the science objectives, the total data volume generated, and the seasonal interdependency, can be tracked.

The heart of the process is the Observations Catalogue (OC), a web-accessed database to collect and analyse all science observation requests. From the OC, the SGS will first determine all science opportunity windows compatible with the spacecraft operational constraints. Secondly, only those compatible with the resources (power and data volume) and pointing constraints will be chosen, including slew feasibility.

The operational quality control and the science data processing pipelines are integrated at system level with the OC allowing to monitor deviations between planned and executed observations and when possible, feed back the results into the science planning. In addition, the generation of science products ready-to-archive compatible with NASA’s Planetary Data System (PDS) standards, a mission archive providing access to the scientific and operational products throughout the different mission phases and their integration with the OC allows full traceability of scientific products with planning operational inputs.

  PS05-D5-PM2-P-022 (PS05-A022)
 
CDPP Activities in Planetary Plasma Sciences
Vincent GÉNOT1#+, CDPP TEAM2, Chihiro TAO3
1 Research Institute Astrophysics and Planetology, France, 2 National Centre for Scientific Research, France, 3 National Institute of Information and Communications Technology, Japan
#Corresponding author: vincent.genot@irap.omp.eu +Presenter

The French plasma physics data centre (CDPP, cdpp.eu) is established for nearly 20 years and proposes a wide range of plasma datasets together with refined analysis tools. The past years have seen the development of several approachs to tackle the questions relative to solar wind interaction with planetary environments. For instance, collaborations with agencies (NASA/PDS) and instrument consortia (Rosetta, JUICE) led the CDPP to offer varied datasets via its AMDA tool (amda.cdpp.eu); such data can also be visualized in their 3D context with the 3Dview tool (3dview.cdpp.eu). Moreover recent connections with simulation databases also permits direct models/observations comparisons. Finally a solar wind propagation model (Tao et al.) has been deployed and enables parameters predictions at planets, comets and interplanetary spacecraft. This data+tools environment will be presented via scientific use cases.

  PS05-D5-PM2-P-023 (PS05-A026)
 
The Mars Express/ASPERA-3 and Venus Express/ASPERA-4 Solar Wind Databases
Robin RAMSTAD#+, Stas BARABASH, Yoshifumi FUTAANA, Xiao-Dong WANG, Mats HOLMSTRÖM
Swedish Institute of Space Physics, Sweden
#Corresponding author: robin.ramstad@irf.se +Presenter

The upstream solar wind environments at Mars and Venus are often thought to influence, or be the major drivers of many processes in the planets’ upper atmospheres and induced magnetospheres. To facilitate studies of such processes and general heliophysics, the PI-institute of the ASPERA-3 and ASPERA-4 plasma particles packages aboard Mars Express and Venus Express has developed a database of official solar wind moments (density, velocity, temperature) to be publicly available and archived. We present the methods used to develop these moments, including the results of intercalibrations with other missions (ACE/WIND/STEREO/MAVEN) and the first solar wind statistics collected at Mars over a full solar cycle.

  PS06-D5-PM2-P-014 (PS06-A003)
 
Jupiter's Stratosphere Visited by Cassini: Roles of Aerosols and the Implications on Exoplanets and Brown Dwarfs
Xi ZHANG#+, Diana POWELL
University of California Santa Cruz, United States
#Corresponding author: xiz@ucsc.edu +Presenter

In December 2000, the Cassini spacecraft flew past Jupiter en route to Saturn. During the months-long Jupiter flyby, a wealth of information was obtained. In this presentation, we show how Cassini observations have significantly changed our understanding of Jupiter’s stratosphere. We have derived spatial maps of temperature and hydrocarbon tracers from the Cassini infrared spectra (Zhang et al. 2013a, PSS), and aerosol maps from Cassini ISS images (Zhang et al. 2013b, Icarus). Based on those observations, we show that gases alone cannot maintain the global energy balance in Jupiter’s stratosphere. Instead, a thick aerosol layer consisting of fluffy, fractal aggregate particles produced by photochemistry and auroral chemistry dominates the stratospheric radiative heating at middle and high latitudes, exceeding the local gas heating rate by a factor of 5 to 10 (Zhang et al. 2015, Nature Communications). A recent three-dimensional general circulation model (GCM) shows that this new radiative energy distribution has a significant impact on our previous understanding of the Jovian stratosphere dynamics. Since aerosols and clouds are ubiquitous in the atmospheres of other giant planets and many Jupiter-sized and sub-Jupiter-sized exoplanets (e.g., HD189733b, GJ436b and GJ1214b). We also argue that fractal aggregate particles may also play a significant role in controlling the atmospheric radiative energy balance on those planets. We investigated the aerosol and cloud formation in a state-of-the-art aerosol microphysics model recently developed in our group for hot Jupiter and brown dwarfs. Specially, we focused on the effects of dynamical transport and radiative energy distribution (e.g., from the day-night temperature contrast on tidally-locked exoplanets) on the vertical distribution of the aerosols and clouds. We also systematically studied the evolution of particle size distribution in the atmosphere and its significant influence on the observed high-resolution spectra and phase curves of exoplanets and brown dwarfs.  

  PS06-D5-PM2-P-015 (PS06-A009)
 
Deriving Homopause Temperatures of Jupiter Using Low-Resolution 3-μm Spectra of Methane
Sang Joon KIM#+
Kyung Hee University, South Korea
#Corresponding author: sjkim1@khu.ac.kr +Presenter

We are expecting low-resolution (R~300) infrared spectra of Jupiter from the upcoming observations by JUNO’s infrared 2-5 μm spectrograph during the encounter with Jupiter approximately starting from July 4, 2016. Although the resolution is not enough to resolve the 3-μm P, Q, R branch lines of CH4, the gross envelopes of the P, Q, R branches should provide information on rotational temperatures. The rotational temperatures are useful because they can be regarded as local temperatures, as discussed by Kim et al. (2014, Icarus, v. 237, p. 42). Since the 3-μm CH4 emission is mostly formed at micro-bar pressure levels, the derived rotational temperatures represent the local temperatures near the hompause of Jupiter. We present a method to derive homopause temperatures from the low-resolution spectra, and discuss possible sciences extracted from the constructed maps of homopause temperatures over the auroral and non-auroral regions of Jupiter. 

  PS06-D5-PM2-P-017 (PS06-A015)
 
Ion Composition of the Thermal Plasma in the F-Ring Region of Saturn
Wing-Huen IP#+
National Central University, Taiwan
#Corresponding author: wingip@astro.ncu.edu.tw +Presenter

In the final phase of the Cassini mission in 2016-2017, the spacecraft will first move to orbits with periapse outside the F-ring and then to orbits grazing the upper atmosphere of Saturn. These trajectories will provide the unique opportunity to sample the structures and composition of Saturn’s ionosphere but also those of the main rings. From an assessment of the neutral gas and plasma environment of the rings, we investigate the formation of molecular ions and nano-grains in the areas to be probed by Cassini during its F-ring and Proximal orbits.

  PS06-D5-PM2-P-018 (PS06-A019)
 
What Can We Learn from Light Curve of Io Plasma Torus?
Fumiharu SUZUKI1#+, Kazuo YOSHIOKA1, Go MURAKAMI2, Fuminori TSUCHIYA3, Tomoki KIMURA4, Ichiro YOSHIKAWA5
1 University of Tokyo, Japan, 2 Japan Aerospace Exploration Agency, Japan, 3 Tohoku University, Japan, 4 RIKEN, Japan, 5 The University of Tokyo, Japan
#Corresponding author: suzuki@astrobio.k.u-tokyo.ac.jp +Presenter

The satellite of Jupiter, Io, continuously supplies volcanic gases to the Jovian magnetosphere. These gases form a dense torus encircling Jupiter along the orbit of Io, and called Io Plasma Torus (IPT). Voyager’s observation of IPT discovered significant radiation in the extra ultraviolet (EUV) range. Various emission lines from the ions in the EUV range are excited by electron impact and the intensity of each emission line contains information about the ion and electron densities and the temperature of the electrons.  It is possible to model an IPT plasma that produces an EUV spectrum that best matches the observations. This method provides estimates of core electron density, temperature, and ion composition. However, it is impossible to derive ‘hot’ electron temperature by this method. Because ‘hot’ electrons play essential role in heating cold electrons and ions, to define the temperature of this component is important for investigation of the whole energy flow in IPT. The HISAKI/EXCEED was launched in September 2013 by the Epsilon rocket. Now it is orbiting around the Earth. EXCEED is a space telescope dedicated for planets and has an advantage of long-term and continuous monitoring of IPT in the EUV range. EXCEED’s observation revealed long-term and short-term variation of IPT brightness, such as periodic variation and sudden brightenings. We succeeded to fit a model to IPT light curve and found that the light curve of IPT indicates the injection timescale or the collisional relaxation time of the hot electrons, which depends on temperature of the hot electrons. In this presentation, we will show what we can learn from IPT light curve obtained by the EXCEED observation.

  PS06-D5-PM2-P-019 (PS06-A020)
 
Time Variation of ENA Fluxes Generated by Energetic Particle Injection Events in the Saturnian Magnetosphere : Comparison Between Cassini MIMI/INCA Observations and Simulations
Ching Hua SHEN1#+, Wing-Huen IP1, Iannis DANDOURAS2, Philippe GARNIER2
1 National Central University, Taiwan, 2 University of Toulouse, France
#Corresponding author: m1029002@gm.astro.ncu.edu.tw +Presenter

In a planetary magnetosphere, Energetic Neutral Atoms (ENAs) are generated by charge exchange collisions between energetic ions and neutral gas. The INCA (Ion and Neutral CAmera) instrument onboard the MIMI experiment of the Cassini spacecraft provides ENA images for hydrogen and oxygen for energies between 10 keV and 220 keV depending on the mode. An important discovery of INCA concerns the appearance of source regions of hydrogen ENAs rotating around Saturn outside the orbit of Encecladus [Jurac and Richardson, 2005; Hansen et al., 2006]. The intensity of the ENA flux tends to brighten up in the midnight to dawn sector, which might be associated with the higher occurrence of energetic charged particles injection events in this region. In this study, we examine the time evolution of a cloud of energetic ions in drift motion relative to the rotating magnetosphere. Besides the dispersal of the energetic ions as a function of their energies, the charge exchange interaction with the neutral cloud created by Enceladus has been simulated. To figure out the possible processes that affect the temporal and spatial variations of ENAs, we examined the effect of an extra midnight to noon electric field, of partial corotation of the plasma and of a magnetic field deduced from MAG magnetic field measurements. A comparison with observational results will be presented. 

References:

1. Hansen,C.J.,L.Esposito,A.I.F.Stewart,J.Colwell,A.Hendrix,W.Pryor, D. Shemansky, and R. West, 2006. Enceladus water vapour plume, Science,311,1422–1425.

2. Jurac, S., Richardson, J.D., 2005. A self-consistent model of plasma and neutrals at Saturn: neutral cloud morphology. Journal of Geophysical Research (Space Physics) 110 9220–+.

  PS06-D5-PM2-P-020 (PS06-A022)
 
On the Extreme Conditions of Titan’s Thermosphere
Jen-Kai HSU1#+, Ian LAI1, Wing-Huen IP1, Jun CUI2,3
1 National Central University, Taiwan, 2 Chinese Academy of Sciences, China, 3 Macau University of Science and Technology, China
#Corresponding author: tabriskai.hsu@gmail.com +Presenter

During its orbital motion around Saturn, Titan moves through different regions of the magnetosphere which can be broadly classified as the lobe and the current sheet. In addition, it will traverse the front-side magnetosphere and the near-tail on the night side of Saturn. The magnetic field and plasma environment take only different physical characteristics accordingly. We examined the vertical distributions of several major species including N2, CH4 and H2 in response to plasma interaction effects in the lobe and current sheet, respectively. The neutral gas measurements are from the Cassini Ion Neutral Mass Spectrometer (INMS) obtained at Titan encounters from 2005 to the most recent time. The classification of the plasma conditions (i.e., lobe vs current sheet) is derived from the Cassini magnetometer measurements.  It is found that there is no obvious correlation between the thermospheric structures and the plasma conditions even though there is a hint that the thermospheric temperature could be lower when Titan was in the lobe than in the current sheet. From a statistical analysis of the atmospheric parameters we identify the Titan thermosphere with the lowest exospheric temperature (Tex = 122 K) and the highest Tex (= 160 K). The corresponding density distributions of methane and hydrogen are compared and their Jeans escape rates at extreme values of Tex are derived. In addition, based on the probability distribution of the escape rates, we can obtain the average escape rates over a solar cycle and the duration of most of the Cassini mission.

  PS06-D5-PM2-P-021 (PS06-A023)
 
A Statistical Study of Titan’s Exospheric Structures Under Different Magnetospheric Conditions Via Ena Imaging and In-Situ Energetic Ion Observations by the Cassini Mimi Instrument
Ching Hua SHEN1#+, Philippe GARNIER2, Iannis DANDOURAS2, Wing-Huen IP1
1 National Central University, Taiwan, 2 University of Toulouse, France
#Corresponding author: m1029002@gm.astro.ncu.edu.tw +Presenter

Besides solar UV radiation, Titan’s exosphere is subject to heating by magnetospheric interaction. These include atmospheric sputtering by energetic ions and electron impact. The imaging observations of energetic neutral atoms (ENA) created by charge transfer process between the neutral gas and energetic H+ and O+ obtained during close Titan encounters and in-situ measurements of the energetic charged particles can be combined to produce a consistent picture of the dynamical response of Titan’s exosphere to the Saturnian magnetosphere, in either the lobe or the current sheet. The results of some typical cases will be described in this report.

  PS06-D5-PM2-P-022 (PS06-A025)
 
The Complex Highly Structured Near Enceladus Environment: Analysis of Cassini UVIS Image Cube Vectors in the Fuv
Donald SHEMANSKY1,2#+, Jean YOSHII1, Candice HANSEN3, Amanda HENDRIX3, Xianming LIU1, Yuk YUNG4
1 Space Environment Technologies, United States, 2 University of Southern California, United States, 3 Planetary Science Institute, United States, 4 California Institute of Technology, United States
#Corresponding author: dshemansky@spacenvironment.net +Presenter

Cassini UVIS image cubes of Enceladus from a spacecraft range of <= 300 RE show complexity in the <20 RE region of the satellite center. This presentation discusses some of the salient features. The image cube matrix discussed here is a virtual 20 X 20 RE structure  centered on the satellite body with pixel size 0.2 X 0.2 RE. The pixels are composed of FUV spectral vectors accumulated from multiple exposures by the Cassini experiments in the years 2010 - 2015. In spite of the multiple year exposure, the matrix structure is significantly non-uniform in brightness and spectral content. The features that can be presented at this time are: 1) The pixels at the center of the body show a strong solar reflection that over the 1500 – 1900 A region indicates a constant structureless  albedo. 2) The central pixels show no discrete emissions  other than a weak optically thick  atomic hydrogen resonance line (HLya)at 1216 A. 3) Above the limb the solar reflection spectrum appears at irregular locations. One of these is recognized as the south polar plume. The plume solar reflection albedo shows a multiply scattered spectrum dominantly composed of hydrocarbon absorbers, primarily C2H4. 4) Above the limb, the HLya line shows spatially irregular structure with emission peaks in the north 50X brighter than the signal from body center.  No discrete emissions other than HLya are observed in the < 2RE region above the limb. The neutral torus at the Enceladus orbit shows only the OI 1304 A line emission. Limits on the presence of other species, H2 in particular, will be presented.

  PS08-D5-PM2-P-013 (PS08-A002)
 
Simulation of Mars Spacecraft Precise Orbit Determination and Martian Gravity Field Recovery
Xuan YANG+, Jianguo YAN#, Mao YE, Weitong JIN
Wuhan University, China
#Corresponding author: jgyan@whu.edu.cn +Presenter

Martian gravity field is important to Mars spacecraft orbit determination and Mars interior structure research, the accuracy and resolution of it will be improved as more and more Mars exploration are under consideration. Especially in China there will be a Mars mission around 2018, considering of this point we develop a Mars precision orbit determination and dynamical parameters solution software. Based on this software we analysis the Martian gravity field model character by orbit prediction. Furthermore, we do a Martian gravity field recovery using non-polar elliptic orbital of Chinese Mars mission, and study its contribution to current Martian gravity field which are mainly developed from polar circular orbiters. We find that after including this mission, the gravity field accuracy will have a significant improvement compared with polar orbit only. The model accuracy is assessed by power spectrum analysis and precise orbit determination. Our research will provide reference for the real orbital tracking data process of future Chinese Mars mission.

  PS08-D5-PM2-P-014 (PS08-A003)
 
Simulation Analysis of the Short-Arc Orbital Determination Accuracy for New Horizons
Weitong JIN+, Fei LI#, Jianguo YAN, Mao YE, Xuan YANG
Wuhan University, China
#Corresponding author: fli@whu.edu.cn +Presenter

The New Horizon mission is executed by National Aeronautics and Space Administration (NASA) to explore Pluto, Charon and other Kuiperbelt objects. In this work we do the orbital prediction and simulated precision orbit determination of the New Horizon spacecraft using our own software package. We first implement orbit prediction in short arcs in light of N-body perturbation and solar radiation pressure and compare with the ephemeris from SPICE. Then we generate simulated observations with Doppler range, range rate and VLBI measurement, and implement a simulation analysis of New Horizons’ orbit determination. Finally we analyze the contribution of various tracking data for the precision orbit determination. Our work will provide reference for real orbital tracking process.

  PS08-D5-PM2-P-015 (PS08-A006)
 
Spectrophotometric Modeling and Mapping of Ceres
Jian-Yang LI1#+, Lucille LE CORRE1, Vishnu REDDY1, Andreas NATHUES2, Martin HOFFMANN2, Michael SCHAEFER2, Mauro CIARNIELLO3, Stefano MOTTOLA4, Stefan E. SCHRÖDER4, Carol RAYMOND5, Christopher RUSSELL6
1 Planetary Science Institute, United States, 2 Max-Planck Institute for Solar System Research, Germany, 3 National Institute for Astrophysics, Italy, 4 German Aerospace Center, Germany, 5 California Institute of Technology, United States, 6 University of California, Los Angeles, United States
#Corresponding author: jyli@psi.edu +Presenter

During the rendezvous with Ceres, Dawn Framing Camera (FC) collected images covering a wide range of illumination and viewing geometries of the surface of this inner most dwarf planet through seven color filters from 440 nm to 980 nm and a panchromatic filter.  This dataset enables a comprehensive study of the photometric properties of Ceres.  Although the overall albedo variation on Ceres is about 15%, many regions 10s km in size or smaller have geometric albedos up to 0.5.  The geology on Ceres is highly complex under its unusual mineralogical composition and water ice content based on the currently incomplete understanding.  The detailed mapping of the photometric properties across the whole surface of Ceres could therefore potentially reveals clues about the composition and geologic processes acting on the surface.  Such maps could also be used to perform photometric corrections to imaging data to produce seamless mosaics.  The objective of this work is to derive the globally averaged photometric parameters, as well as maps of the fundamental photometric properties of Ceres over all colors covered by the Dawn FC, including albedo, phase function, and roughness.  We will report the detailed photometric modeling of Ceres on a global scale in multiple wavelengths in the visible based on the FC images, as well as the results about photometric property mapping.  The mapping is performed by subdividing the surface into longitude-latitude grid of 0.5º-1º wide, and applying separate photometric modeling to the grid.  We will show the maps of photometric parameters, compare it with the maps generated with photometric corrections using the global average photometric parameters, and interpret these maps in the context of mineralogy and geology.

  PS08-D5-PM2-P-016 (PS08-A009)
 
Scientific Outcomes of Some Past Small Bodies Missions
Lucy MCFADDEN#+
NASA Goddard Space Flight Center, United States
#Corresponding author: lucy.mcfadden@nasa.gov +Presenter

The hallmark of a successful scientific mission is to have clearly stated scientific goals matched by achievable scientific measurements and instrument requirements providing those measurements.  A dedicated team of scientists and engineers with adequate funding yields scientific discovery. NASA’s Discovery Program complements the Agency’s flagship missions and has advanced understanding of small bodies. The Near-Earth Asteroid Rendezvous (NEAR) mission was the first to orbit an asteroid, the 34 x 11 x 11 km, S-type, Earth-approaching asteroid, 433 Eros. Evidence for it being partially differentiated comes from its density, chemistry and surface mineralogy. The Deep Impact mission’s goal was to look beneath the surface of comet Tempel 1 by excavating material from a spacecraft projectile traveling at 10 km/s relative to the comet. While the operations proceeded as planned, the nature of the surface of the comet was not anticipated and the ejected debris saturated the telescopes on the flyby spacecraft.  However, because the team planned an extensive observing campaign using all existing telescopes on the ground and in space, the Spitzer Telescope observed the ejected debris and found molecules that condense through a large range of temperatures indicating significant mixing in the early stages of solar system formation. This, along with results from the Stardust mission changed the formation paradigm that comets form solely in the cold, outer regions of the solar system.  The Deep Impact mission received funding for an extended mission and flew past a second comet adding to the range of comets observed in situ and also became an exoplanet mission. The Dawn mission to Vesta and dwarf planet Ceres explained decades-long questions about the basaltic achondrite meteorite parent body and we have deeper insights into the nature of a silicate and water-rich dwarf planet.

  PS08-D5-PM2-P-017 (PS08-A011)
 
Photometric Comparison of Geological Features on Cometary Nuclei
Xiao-Duan ZOU#+, Jian-Yang LI
Planetary Science Institute, United States
#Corresponding author: zouxd@psi.edu +Presenter

Direct imaging of comets by spacecraft enabled disk-resolved photometry of cometary nuclei. Comparative study of photometric properties of similar and different geological terrains of comets helps understand their general physical properties. Does certain terrain (smooth area, ice patches, etc.) on different comets have similar physical properties that distinguish them from other types of terrains? To answer this question, we first compare different smooth areas on comets 9P/Tempel 1 and 103P/Hartley 2 using the Hapke model. The Hapke roughness parameter, θ, of the smooth areas on either Tempel 1 or Hartley 2 showed no statistically significant evidence that distinguish them from other areas. We compare the phase functions of the reflectance markings in the smooth areas with the surrounding areas on Tempel1 in the Stardust-Next data, and study the limb-darkening profiles of the markings on both Tempel1 and Hartley 2. We also performed forward modeling with both the Hapke model and the Buratti model. In addition, we characterize the visible color and photometric properties of water ice patches on Tempel 1 and Hartley 2, and survey through the surfaces of a few other comets imaged by spacecraft to identify areas or spots that possibly contain water ice. The detailed results of our research will be presented.

  PS08-D5-PM2-P-018 (PS08-A019)
 
Radar Model Fusion of Asteroid (4179) Toutatis Via Optical Images Observed by Chang'e-2 Probe
Wei ZHAO1+, Wei ZHAO1, Peng LIU1#, Lei SUN1, Jiangchuan HUANG2, XiangLong TANG1
1 Harbin Institute of Technology, China, 2 China Academy of Space Technology, China
#Corresponding author: pengliu@hit.edu.cn +Presenter

Asteroid (4179) Toutatis has been modeling by ground-based radar observations until Dec 13th, 2012, when distinct optical images of Toutatis were captured during the Chang’e-2 flyby at the shortest distance for the first time. The surface details on Toutatis in the optical images are abundant enough to reinforce the radar model descriptions. Under this context, we customized a method of frequency domain data fusion, which combines the topography information of radar model and the 3rd 18 dimension information estimated from optical image by shape from shading algorithm, and gave out a new Toutatis’ radar model. Amodel with abundant surface characteristics had been resulted.

  PS09-D5-PM2-P-010 (PS09-A002)
 
PDS Cometary Archive from Giotto to Rosetta
Ludmilla KOLOKOLOVA1#+, Michael A'HEARN1, Anne RAUGH1, Tilden BARNES1, Edwin GRAYZECK2
1 University of Maryland, United States, 2 NASA Goddard Space Flight Center, United States
#Corresponding author: ludmilla@astro.umd.edu +Presenter

The PDS is NASA’s permanent archive for all planetary data obtained by its spacecraft missions to solar system bodies, and has grown to include ground-based and laboratory data to support mission planning and the analysis of the resulting data.The PDS is structured as a distributed archive, with data germane to various disciplines (atmospheric sciences, geosciences, small bodies, etc.) hosted by and with specialists having vested interest in collecting, maintaining, and using the data – the PDS Nodes. The Small Bodies Node (SBN) is the PDS home for observations of small solar system bodies – comets, asteroids, dwarf planets, interplanetary dust, meteorites, etc. The SBN itself has two specialist subgroups – the Comet group located at the University of Maryland and led by Mike A’Hearn, and the Asteroid/Dust group located at the Planetary Sciences Institute in Tucson, AZ, headed by Eric Palmer. Since bringing the IHW data into its archives nearly 25 years ago, SBN has archived, or is archiving, the data resulting from every deep-space mission to a small body.The Comet group now hosts and maintains data from: the International Cometary Explorer to comet 21P/Giacobini-Zinner ; the Giotto Extended Mission to comet 26P/Grigg-Skjellerup; the Deep Space 1 observations of comet 19P/Borrelly; the Deep Impact mission to comet 9P/Tempel 1 and its extended mission (EPOXI) to comet 103P/Hartley 2 (the EPOXI mission also included remote observations of comets C/Garradd (2009 P1) and C/ISON (2012 S1)); the Stardust Mission to comet 81P/Wild 2, and its extended mission, Stardust NexT,  to comet 9P/Tempel 1 and recent balloon mission BOPPS. Currently, the SBN Comet group is focused on the Rosetta mission to comet 67P/Churyumov-Gerasimenko (1969 R1). To date there are over 300 Rosetta datasets   (672GB) hosted by the SBN. The SBN cometary holdings include ground-based data ranging from images and spectra, through reference data sets of reported results and characteristics compiled from the literature, to laboratory spectra of various ice and mineral samples.

  PS09-D5-PM2-P-011 (PS09-A004)
 
VESPA: Enlarging the Planetary Science Virtual Observatory
Stephane ERARD1#+, Baptiste CECCONI2, Pierre LE SIDANER1, Angelo Pio ROSSI3, Maria Teresa CAPRIA4, Bernard SCHMITT5, Nicolas ANDRE6, AnnCarine VANDAELE7, Manuel SCHERF8, Ricardo HUESO9, Anni MÄÄTTÄNEN10, William THUILLOT2, Nicholas ACHILLEOS11, Chiara MARMO12, Ondrej SANTOLIK13,14, Kevin BENSON11
1 Paris Observatory, France, 2 Observatoire de Paris, France, 3 Jacobs University, Germany, 4 National Institute for Astrophysics, Italy, 5 Joseph Fourier University, France, 6 Centre d'Etude Spatiale des rayonnements, France, 7 Belgian Institute for Space Aeronomy, Belgium, 8 Institut für Weltraumforschung, Austria, 9 University of the Basque Country, Spain, 10 Institut Pierre Simon Laplace, France, 11 University College London, United Kingdom, 12 University of Paris-Sud, France, 13 Chinese Academy of Sciences, Czech Republic, 14 Charles University in Prague, Czech Republic
#Corresponding author: stephane.erard@obspm.fr +Presenter

In the frame of the Europlanet2020-RI program (2015-2019), a Virtual Observatory (VO) dedicated to Planetary Science is developed. The activity focuses on setting up new, interoperable data services, and adapting the capacities of Virtual Observatory tools to the needs of Planetary Science.  Besides, training to both users and potential data providers is provided each year during the major two conferences of the field that take place in Europe (EGU and EPSC).

The activity is organized around 6 science themes, which study specific needs to support the study of planetary surfaces, atmospheres, and magnetospheres, small bodies, exoplanets, and surface spectroscopy. These 6 themes will implement new tools such as a VO-GIS link, workflows to automatically process atmospheric and magnetospheric data, support to coordinated ground-based observations, definition of a standard naming scheme for solar system coordinate frames, etc. 

Sustainability of the programme outcomes will be insured through external collaborations with longer-lived consortia such as IAU, IPDA, and IVOA — the Europlanet/VESPA standards will be discussed and proposed for approval by these consortia. The EPN-TAP data access protocol [1] in particular is currently studied by ESA to provide access to the PSA, and is a project study of IPDA 

The Europlanet 2020 Research Infrastructure project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654208.

Reference

1. Erard et al 2014, Astron & Comp, 7-8, 52-61 http://arxiv.org/abs/1407.5738

  PS09-D5-PM2-P-012 (PS09-A008)
 
Webgeocalc and Cosmographia: Modern Tools to Access Spice Archives
Boris SEMENOV#+
National Aeronautics and Space Administration Headquarters(NASA), United States
#Corresponding author: Boris.Semenov@jpl.nasa.gov +Presenter

For more than two decades navigation data from most US and international space science missions have been archived as "SPICE"(*) system data files (a.k.a. SPICE kernels), assembled into PDS compliant data sets, residing at the Navigation and Ancillary Information Facility (NAIF) node of NASA’s PDS, ESA’s PSA, and JAXA’s Hayabusa archives. The traditional way for accessing data from these archives was by downloading the whole or a subset of a SPICE data set, installing the SPICE toolkit available from NAIF, and writing an application calling APIs from the core SPICE Toolkit library to compute geometric parameters of interest. While this approach did and still does provide the greatest flexibility in implementing geometric computations of interest, it proved to be complicated for users with little programming abilities, required data to be always copied to the users’ workstations, and lacked any out-of-the-box visualization capabilities. To address these shortcomings NAIF developed the WebGeocalc tool and extended the publicly available Cosmographia program to use SPICE. WebGeocalc (http://naif.jpl.nasa.gov/naif/webgeocalc.html) is based on Web client-server architecture and provides, in a web browser, a convenient GUI to specify computations done by the geometry server accessing SPICE archive data. The WebGeocalc server computation capabilities can also be accessed via a programmatic REST interface, essentially making it a web service. Cosmographia (http://naif.jpl.nasa.gov/naif/cosmographia.html) is a 3D solar system visualization program able to accurately render solar system (target) bodies, spacecraft trajectories and orientations, instrument field-of-view "cones" and footprints based on SPICE archive data. The program and SPICE archives of interest must be downloaded and installed on the user’s workstation, and configured using detailed instructions provided by NAIF.

The research described in this publication was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Keywords  Spacecraft, Planet, Instrument, Camera-matrix, Events 

  PS09-D5-PM2-P-013 (PS09-A012)
 
The Introductory Planetary Data System in China
Zongcheng LING#+, Jiang ZHANG, Bo LI
Shandong University, China
#Corresponding author: zcling@sdu.edu.cn +Presenter

The Planetary Data system (PDS), initiated in the early 1980s by NASA in United States, has become a world-wide standard for planetary datasets. With the successful "orbiting" and "landing" of the Moon, China's lunar exploration program (CLEP) has already made great achievements. A large amount of lunar datasets compatible to PDS have been released by the Ground and Research Application System (GRAS) of CLEP to the science community, leading to many new scientific discoveries of the Moon. However, more and more scientists in China start to recognize the importance of data quality and access for better science returns, with regards to the data format, documentations, validations, and distributions, etc.

To meet the needs of high-quality planetary data archiving in China, Shandong University at Weihai set up the first PDS laboratory in China on July 24, 2007. This is by an international educational collaboration between School of Space Science and Physics, Shandong University at Weihai, and Department of Earth and Planetary Sciences, Washington University in St. Louis. The main objectives of the PDS lab is to introduce the concept of PDS archiving, bridge the gap between NASA PDS and Chinese PDS, and serve to the young Chinese planetary science community. We have jointed the International Planetary Data Alliance (IPDA) in 2010, which is an international organization for the ease discovery, access and use of planetary data. In this work, we will overview the history of the introductory planetary data system from United States to China. Then we will introduce our experiences and progresses on the processing and validation of the lunar data returned by Chang'e missions. We are developing an online planetary data query system on our website (http://pds.wh.sdu.edu.cn/). For the future, we will continue our endeavor to promote the PDS standards for our returned planetary datasets in China. 

  PS10-D5-PM2-P-008 (PS10-A005)
 
Constraining the Microphysical Properties of Dust Particles on the Nucleus of 67P/CG from MIRO and COSIMA Data
Paul HARTOGH#+, Yuri SKOROV, Ladislav REZAC
Max Planck Institute for Solar System Research, Germany
#Corresponding author: hartogh@mps.mpg.de +Presenter

Both, the composition and also the microphysical structure of the dust grains emitted from the nucleus is one of the important open questions in understanding the comets. Since the Rosetta spacecraft arrived at the come (Aug, 2014), a large number of dust particles emitted from the 67P nucleus have been gathered by the COSIMA instrument (Schulz et al. 2015, Nature 518). The image analysis of these grains indicate a rather complex structure: large agglomerates made up from smaller pieces, or agglomerates containing both, large and small tightly packed particles. Whether this complex structure is inherent in the nucleus dust (e.g. hierarchic structure of dust (Skorov & Blum 2012, Icarus 222)), or are the detected particles actually pieces (fragments) of the destroyed homogeneous porous dust layer remains is unknown. From the physical consideration of thermal and strength properties of the nucleus, the dust layers made from the different grain characteristics are rather different. Using the information on thermal inertia, and brightness temperature differences from the MIRO instrument (Schloerb et al 2015 A&A 583) we performed  numerical experiments for two models of nucleus porous dust layers. 1) a homogeneous porous layer containing aggregates of dust with sizes ~10-30 µm, and 2) hierarchic porous layer containing aggregates of sizes of ~100-500 µm, where "pseudo"-monomers (building blocks), in turn, are porous aggregates of sizes of ~10-30 µm. The goal of the systematic numerical simulations are: 1) is it possible to select a preferred model of the surface dust layer structure based on data MIRO data, 2) which observational conditions are best to address this question.

  PS10-D5-PM2-P-009 (PS10-A009)
 
Feasibility Study for Mars Landing with Small Space Probe
Akifumi WACHI1#+, Yuki KOSHIRO1, Yasuko KASAI2, Shinichi NAKASUKA1
1 The University of Tokyo, Japan, 2 National Institute of Information and Communications Technology, Japan
#Corresponding author: wachi@space.t.u-tokyo.ac.jp +Presenter

Mars landing missions have brought us great scientific insight. A lot of Mars landers have sought the origin or evidence of life on Mars. In 2013, THz observation by Hershel Space Observatory suggested that oxygen exists on Mars denser on surface than elsewhere. High density of oxygen on the surface may be an evidence of life on Mars. Therefore, it will become significant achievement to obtain the altitude profile of the density of oxygen.

However, Mars Entry, Decent, and Landing (EDL) is one of the most difficult missions in space explorations. More than half of the Mars EDL missions have ended in failure. Even though some of the Mars EDL missions are successful, but their systems tended to be quite complicated and expensive.

This study is on the preliminary design of Mars landing mission with a small space probe. In spite of its simplicity, we demonstrate some feasibility of our Mars landing mission via small space probe. Unfortunately, however, there must be several limitations on scientific observations or telecommunication. In particular, the landing site is quite limited in terms of telecommunication or trajectory design. In this research, the result of preliminary design and critical issues are discussed.

  PS10-D5-PM2-P-010 (PS10-A010)
 
A Vector Near-Field Antenna Measuremnt System at Thz Band
Jie HU#+, Zheng LOU, Kang-ming ZHOU, Wei MIAO, Sheng-Cai SHI
Purple Mountain Observatory, China
#Corresponding author: jiehu@pmo.ac.cn +Presenter

This paper is to introduce the planar vector near-field antenna measurement system developed at PMO. The system is based on wideband high sensitivity superconducting receiver equipped with a quasi-optical probe for high resolution near-field sensing. The frequency that can be measured ranges from 100GHz to 850GHz. The dynamic range of the system is about 40~50dB. Antenna measurements at 500GHz and 850GHz will be shown in detail. 

  PS10-D5-PM2-P-011 (PS10-A011)
 
A Compact, Low Power Tunable Laser Spectrometer for Trace Gas Measurement in Planetary Atmospheres
Scot RAFKIN1#+, Keith NOWICKI1, Joel SILVER2, Mark PAIGE2
1 Southwest Research Institute, United States, 2 Southwest Sciences, Inc., United States
#Corresponding author: rafkin.swri@gmail.com +Presenter

A tunable laser spectrometer (TLS) capable of simultaneously measuring many of the key photochemical species in planetary atmospheres is presented.   The instrument consists of a low-power (<10 mW) and low mass (<50 mg) vertical cavity emitting laser source and photodetector, a multi-pass optical cell to provide a long absorption path in a compact design, and laser driving and digital signal processing electronics.  The sensor takes advantage of two key technological developments: 1) a patented multiple-pass optical cell design that uses small mirrors and dense spot patterns to give a long optical path with a small footprint; and 2) a low power and compact electronics system.  Designs for Mars and Venus are mature, allowing for deployment on probe or balloon missions to either planet, and deployment on landed spacecraft at Mars.   The instrument is immune to the corrosive sulfuric acid environment of Venus and is capable of operating at temperatures of up to at least 370 K; the instrument is ideal for an atmospheric balloon investigation at altitudes of 50 km or higher.  The large diurnal temperature range of Mars is not a challenge, and the optical design is robust against dust contamination.  The moduler design of the subsystems allow for easy adaptations for other atmospheres like Jupiter and Venus with little difficulty.  The major advantage of this system over previously developed TLS instruments is the multichannel gas measuring capability, an increase in path length and sensitivity without an increase in mirror size, a dramatic decrease in mass and power, and the robust nature of the design in a hostile environment.  Most of the instrument components and electronics are at TRL-6 with the combined system at TRL-5.  The instrument is currently in field tests.  Current best estimates of total instrument mass and power are 750 mW and 1 kg, respectively.

  PS10-D5-PM2-P-012 (PS10-A013)
 
NbN Superconducting Tunnel Junction Mixer with Wide IF Bandwidth
Dong LIU#+, Jing LI, Sheng-Cai SHI
Purple Mountain Observatory, China
#Corresponding author: dliu@pmo.ac.cn +Presenter

Superconductor-insulator-superconductor (SIS) mixers are the most sensitive coherent detectors of submillimeter radiation. During the past few years, they have been used successfully in submillimeter-wave radio astronomy receivers and atmospheric science, providing sensitivities that approach the quantum limit. NbN superconducting tunnel junctions, with a gap frequency of 1.4THz twice as Nb SIS junctions, are potentially applicable to sensitive heterodyne mixers for THz astronomy and atmospheric research. In this paper, a wide IF bandwidth SIS mixer is introduced, we have investigated the characteristics of IF bandwidth of SIS mixer with twin NbN/AlN/NbN junctions, the theoretical IF noise bandwidth is calculated based on quantum mixer theory and the IF output channel. Also, the noise performance at IF frequency band have been measured using Y factor method with spectrum analyzer and power meter, the result of measurement is analyzed combining with simulated result. Detailed measurement results and analysis will be presented.

  PS10-D5-PM2-P-013 (PS10-A014)
 
Development of Atmospheric Radiative Transfer Code for Simulations of THz Observation for Ganymede Atmosphere
Takayoshi YAMADA1#+, Naohiro YOSHIDA1, Yasuko KASAI2
1 Tokyo Institute of Technology, Japan, 2 National Institute of Information and Communications Technology, Japan
#Corresponding author: yamada.t.bd@m.titech.ac.jp +Presenter

We are developing a terahelz radiative transfer code, named Atmospheric Terahelz RAdiation SimUlator (ATRASU), for the simulation of observation for Ganymede atmosphere. The ATRASU include line-by-line calculation using spectroscopic parameters (line intensity and partition function) from JPL catalogue. The pencil beam was assumed for the geometry of limb and nadir.The local thermodynamic equilibrium (LTE) was assumed. The good agreement was confirmed for the comparison with ARTS (Atmospheric Radiative Transfer Simulator) model  with the difference less than 10% and 5% for H2O and CO spectrum intensity,respectively.

To apply the simulation of the Submillimeter Wave Instrument (SWI) on the JUpiter ICy moon Explorer (JUICE), we are also developing non-LTE condition and instrumental functions. Some feasibility studies will be shown in the presentation.

  PS11-D5-PM2-P-013 (PS11-A004)
 
Solar Wind Interaction with Lunar Magnetic Anomalies: Latest Results
Jan DECA1#, Xu WANG1+, Andrey DIVIN2, Bertrand LEMBEGE3, Stefano MARKIDIS4, Giovanni LAPENTA4, Mihaly HORANYI1
1 University of Colorado Boulder, United States, 2 St. Petersburg State University, Russian Federation, 3 National Centre for Scientific Research, France, 4 Katholieke Universiteit Leuven, Belgium
#Corresponding author: jandeca@gmail.com +Presenter

Discovered by early astronomers during the Renaissance, the Reiner Gamma formation is one of the most peculiar lunar surface features. Observations have shown that the tadpole-shaped albedo marking, the so-called swirl, found on the Oceanus Procellarum is co-located with one of the strongest magnetic anomalies (LMA) on our Moon. In previous work, using a horizontal dipole model [Deca et al. 2014, 2015], we have described the formation of a mini-magnetosphere structure surrounding the swirl pattern, locally shielding the underlying lunar surface from the impinging solar wind, and hinting at a correlation with its main surface albedo brightness marking in a distinctive concentric oval shape. Using the observed magnetic field model [Tsunakawa et al. 2015] in our full-kinetic electromagnetic framework, iPic3D, we reproduce a surface weathering pattern closely resembling the details of the Reiner Gamma swirls. This work therefore provides strong evidence that the solar wind standoff theory for lunar swirl formation is the dominant process to explain the albedo markings of the Reiner Gamma region. We present the latest results in kinetic modeling the solar wind interaction with lunar magnetic anomalies.

This work was supported by NASA’s SSSERVI/IMPACT and by the Swedish National Space Board, Grant No. 136/11. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. Test simulations utilized the Janus supercomputer, supported by NSF (CNS-0821794) and CU Boulder. JD, XW and MH thank the International Space Science Institute in Bern, Switzerland, for supporting International Team 336: “Plasma-Surface Interactions with Airless Bodies in Space and the Laboratory”.

  PS11-D5-PM2-P-014 (PS11-A005)
 
The M-Type Asteroids: Reservoirs of Silicates, Metal and Water
Zoe LANDSMAN1#+, Humberto CAMPINS1, Joshua EMERY2
1 University of Central Florida, United States, 2 University of Tennessee, United States
#Corresponding author: zlandsman@knights.ucf.edu +Presenter

M-type asteroids are found in the main asteroid belt as well as the Near-Earth Asteroid (NEA) population and are characterized by featureless visible spectra with flat-to-red slopes and moderate albedos. Studies in visible, near-infrared, and radio wavelengths show that M-types are compositionally diverse, containing high-temperature silicates, water-bearing silicates and iron-nickel metal. These materials are highly relevant for in-situ resource utilization (ISRU) efforts to support human exploration and commercial activities near Earth, in the asteroid belt, and beyond. Using NASA’s Infrared Telescope Facility and the Spitzer Space Telescope, we are carrying out a spectroscopic study of a sample of main-belt M-type asteroids in the 2-4 micron region and in the mid-infrared (5-40 microns) in order to characterize their hydrated mineral content and thermal properties. Our study includes analysis of spectral features and thermophysical modeling. We compare these results with other published information for each asteroid to build a predictive model of silicate, water and metal content in M-type asteroids. Our findings can be used to determine which M-type NEAs are good candidates for ISRU and provide guidance on what minerals and resources may be available on the objects. Additionally, our study is relevant to the primitive materials likely to be encountered on NEA 2008 EV5, the target of NASA’s Asteroid Redirect Mission (ARM). Although 2008 EV5 is not an M-type, it is likely to have similar hydrated silicates to those we have identified on M-types.

  PS11-D5-PM2-P-015 (PS11-A006)
 
The Basalts of Mare Frigoris
Georgiana KRAMER1#+, Bhavesh JAISWAL2, B. Ray HAWKE3, Teemu OHMAN4, Thomas GIGUERE5, Katherine JOHNSON1
1 Lunar and Planetary Institute, United States, 2 ISRO Satellite Centre, India, 3 Hawaii Institute for Geophysics and Planetology, United States, 4 Arctic Planetary Science Institute, Finland, 5 Intergraph Corporation, United States
#Corresponding author: kramer@lpi.usra.edu +Presenter

M-type asteroids are found in the main asteroid belt as well as the Near-Earth Asteroid (NEA) population and are characterized by featureless visible spectra with flat-to-red slopes and moderate albedos. Studies in visible, near-infrared, and radio wavelengths show that M-types are compositionally diverse, containing high-temperature silicates, water-bearing silicates and iron-nickel metal. These materials are highly relevant for in-situ resource utilization (ISRU) efforts to support human exploration and commercial activities near Earth, in the asteroid belt, and beyond. Using NASA’s Infrared Telescope Facility and the Spitzer Space Telescope, we are carrying out a spectroscopic study of a sample of main-belt M-type asteroids in the 2-4 micron region and in the mid-infrared (5-40 microns) in order to characterize their hydrated mineral content and thermal properties. Our study includes analysis of spectral features and thermophysical modeling. We compare these results with other published information for each asteroid to build a predictive model of silicate, water and metal content in M-type asteroids. Our findings can be used to determine which M-type NEAs are good candidates for ISRU and provide guidance on what minerals and resources may be available on the objects. Additionally, our study is relevant to the primitive materials likely to be encountered on NEA 2008 EV5, the target of NASA’s Asteroid Redirect Mission (ARM). Although 2008 EV5 is not an M-type, it is likely to have similar hydrated silicates to those we have identified on M-types.

  PS11-D5-PM2-P-016 (PS11-A012)
 
NASA’s Solar System Exploration Research Virtual Institute: An International Approach Toward Bringing Science and Human Exploration Together for Mutual Benefit
Greg SCHMIDT#+
National Aeronautics and Space Administration Headquarters(NASA), United States
#Corresponding author: gregory.k.schmidt@nasa.gov +Presenter

The NASA Solar System Exploration Research Virtual Institute (SSERVI) is a virtual institute focused on research at the intersection of science and exploration, training the next generation of lunar scientists, and community development.  The institute is a hub for opportunities that engage the larger scientific and exploration communities in order to form new interdisciplinary, research-focused collaborations.  Its relatively large domestic teams work together along with international partners in both traditional and virtual settings to bring disparate approaches together for mutual benefit.  This talk will describe the research efforts of the nine domestic teams that constitute the U.S. complement of the Institute and how it is engaging the international science and exploration communities through workshops, conferences, online seminars and classes, student exchange programs and internships.  The Institute is centered on the scientific aspects of exploration as they pertain to the Moon, Near Earth Asteroids (NEAs) and the moons of Mars.  It focuses on interdisciplinary, exploration-related science centered around all airless bodies targeted as potential human destinations.  Areas of study reported here will represent the broad spectrum of lunar, NEA, and Martian moon sciences encompassing investigations of the surface, interior, exosphere, and near-space environments as well as science uniquely enabled from these bodies.  The technical focus ranges from investigations of plasma physics, geology/geochemistry, technology integration, solar system origins/evolution, regolith geotechnical properties, analogues, volatiles, ISRU and exploration potential of the target bodies.  SSERVI enhances the widening knowledgebase of planetary research by acting as a bridge between several different groups and bringing together researchers from the scientific and exploration communities, multiple disciplines across the full range of planetary sciences, and  domestic and international communities and partnerships.

  PS11-D5-PM2-P-017 (PS11-A016)
 
Response of Planetary Regolith to Low-Velocity Impacts Under Microgravity Conditions
Julie BRISSET+, Joshua COLWELL#, Adrienne DOVE, Allison RASCON, Kristen BRIGHTWELL
University of Central Florida, United States
#Corresponding author: josh.colwell@ucf.edu +Presenter

The dusty regolith covering the surfaces of asteroids and planetary satellites is very different from terrestrial soil particles and subject to environmental conditions very different from what is found on Earth. The loose, unconsolidated regolith is produced by hyper-velocity micrometeoroid impacts on asteroids and planetary satellites, leading to angular particles in a broad size distribution. In contrast, terrestrial soils are formed by erosional processes leading to more rounded particles with narrower size distributions. In addition, the regolith covering small airless bodies is evolving in a low-pressure and low-gravity environment.

The response of this planetary regolith to low-velocity impacts, such as those that may accompany manned and unmanned exploration activities, may be completely different than what is encountered in terrestrial regolith. Further, the microgravity environment of small asteroids and moons and the absence of gravity can lead to new behaviors. Dust particles from regolith pose a hazard to equipment. The regolith itself is a possible resource for in-situ processing of minerals and elements, and equipment may need to be anchored to the loose regolith. Experimental studies of the response of planetary regolith in the relevant environmental conditions are thus necessary to facilitate future exploration activities.

We carried out a series of impact experiments into simulated planetary regolith in zero- and reduced-gravity conditions on parabolic airplane flights with the Physics of Regolith Impacts in Microgravity Experiment (PRIME). We found that coefficients of restitution of a spherical marble on a bed of regolith decrease by a factor of 10 with increasing impact speeds from ~10 cm/s up to 100 cm/s. The ejecta velocity distributions show a power-law dependence on the impact energy and indicate that the propagation of the impact energy through the regolith is carried out by displacement of the material rather than by a large amount of discrete grain collisions.

  PS11-D5-PM2-P-018 (PS11-A017)
 
Thermophysical Modeling of Near Earth Asteroids: 1627 Ivar
Jenna CROWELL1#+, Ellen HOWELL2, Christopher MAGRI3, Yanga FERNANDEZ1, Sean MARSHALL4, Michael NOLAN2, Brian WARNER5, Ronald VERVACK6
1 University of Central Florida, United States, 2 University of Arizona, United States, 3 University of Maine at Farmington, United States, 4 Cornell University, United States, 5 Center for Solar System Studies, United States, 6 Johns Hopkins University, United States
#Corresponding author: jenlyjones@knights.ucf.edu +Presenter

Our objective is to investigate the complexity and heterogeneity of the surfaces of near-Earth asteroids (NEAs). To achieve this, we have incorporated delay-Doppler radar images, Doppler spectra, and lightcurves to produce detailed shape models [1].  These shape models and near-IR spectra are then used to obtain thermophysical models to analyze the thermal and scattering properties of asteroid surfaces.  Here we present our findings on (1627) Ivar. 

Ivar is an Amor class NEA with taxonomic type of Sqw [2] and a rotation period of 4.795 hours [3].  Our radar data were obtained using the Arecibo Observatory’s 2380 MHz radar.  Lightcurve data were gathered using the 0.35m telescope at the Palmer Divide Station.  The near-IR spectra encompass reflected and thermal regimes (0.8 – 4.1 µm) and were acquired using the SpeX instrument at the NASA IRTF.   

We have used the thermal-modeling code SHERMAN [4,5] to create a thermophysical model of Ivar in order to study the heterogeneity of its surface.  SHERMAN lets us determine which reflective, thermal, and surface properties best reproduce our numerous spectra, which cover many rotational longitudes and vantage points.  Our results suggests signs of heterogeneity, with one of the ends having thermal properties that are consistently different from those of the rest of surface.  This work shows the advantage of having many datasets for deep study of an individual NEA, and with these results, we will learn more about the detailed regolith and surface properties of Ivar and how those properties compare to those of other NEAs.        

References:

1. Crowell et al., in preparation 

2. DeMeo et al. 2009, Icarus 202, 160-180.

3. Crowell et al. 2015, LPSC 46. 

4. Magri et al. 2007, Icarus 186, 152-177.

5. Howell et al. 2015, TherMoPS II. 

This work is partially supported by NSF (AST-1109855), NASA (NNX13AQ46G), CLASS SSERVI (NNA14AB05A), and USRA (06810-05). 

  PS11-D5-PM2-P-019 (PS11-A018)
 
Thermal Expansion, Heat Capacity and Thermal Conductivity Measurements of CM Carbonaceous Chondrites
Cyril OPEIL1#+, Daniel BRITT2
1 Boston College, United States, 2 University of Central Florida, United States
#Corresponding author: opeil@bc.edu +Presenter

Measurement of the low-temperature thermodynamic and physical properties of meteorites provides fundamental data for the study and understanding of asteroids and other small bodies. Of particular interest are the CM carbonaceous chondrites, which represent a class of primitive meteorites that record substantial chemical information concerning the evolution of the early solar system.  Most CM chondrites contain both anhydrous minerals such as olivine and pyroxene found in chondrules, along with abundant hydrous phyllosilicates contained in the meteorite matrix, interspersed between the chondrules.We have measured the thermal conductivity, heat capacity and thermal expansion of several CM carbonaceous chondrites (Murchison, Murray, Cold Bokkeveld, NWA 7309, Jbilet Winselwan) at low temperatures (5–300 K).  The thermal expansion measurements on Murchison and Murray indicate a substantial increase in meteorite volume as temperature decreases from 230 - 210 K followed by linear contraction below 210 K. Such transitions are not typical for other carbonaceous chondrites. Thermal diffusivity as a function of temperature is calculated from measurements of density, thermal conductivity and heat capacity.  Our thermal diffusivity results compare well with previous estimates for similar meteorites, where conductivity was derived from diffusivity measurements and modeled heat capacities; our new values are of a higher precision and cover a wider range of temperatures.

  PS11-D5-PM2-P-020 (PS11-A022)
 
Lightcurve Inversion for Near-Earth Asteroids with Lommel-Seeliger Ellipsoids
Ao WANG1#+, Xiao-Bin WANG1, Karri MUINONEN2
1 Chinese Academy of Sciences, China, 2 University of Helsinki, Finland
#Corresponding author: wangao@ynao.ac.cn +Presenter

Studying the shape, spin and other physical parameters of near-earth asteroids can help to provide information on their origin and  prevent the threat of asteroid impact. On a vase majority of near-earth asteroids, the disk-integrated photometry measurement constitutes the primary source of knowledge. Here, we will analyse photometric data of near-earth asteroids to derive their basic physical parameters--spin parameters and shape, using so-called Lommel-Seeliger ellipsoid (LS ellipsoid) as the brightness model. Namely, a triaxial ellipsoid with a Lommel-Seeliger surface reflection coefficient are applied in brightness model to generate the analytical disk-integrated brightness for a near-earth asteroid. To solve the unknown parameters, an efficient Markov-chain Monte Carlo method (MCMC) is applied, with which the best value of unknown parameters and their uncertainties can be derived .

  PS12-D5-PM2-P-009 (PS12-A004)
 
Study on Interaction Between Diurnal Tide and Atmospheric Aerosols Observed by the Mars Climate Sounder
Zhaopeng WU#+, Tao LI
University of Science and Technology of China, China
#Corresponding author: ustcwzp@mail.ustc.edu.cn +Presenter

The increased local time coverage observed by Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO) can enable direct extraction of thermal tides in Mars middle atmosphere with reduced aliasing. Using temperature profiles from Mars year (MY) 30 to 32, we study the latitudinal and seasonal variations of tides and stationary planetary waves with zonal wave numbers s = 1-3. The amplitude of the migrating diurnal tide (DW1) has strong semiannual variations both in the equatorial region and in the Southern Hemisphere (SH) middle latitudes. Aerosols widely distributed in the atmosphere of Mars, namely, dust and water ice also show apparent diurnal variations, which may be caused by a dynamical process of tidal vertical wind. Tidal response in dust abundance indicates an annual variation with maximum amplitude in aphelion seasons while the background abundance of dust peaks in perihelion seasons when global dust storm occurs frequently, which suggests that extremely large abundance of dust may restrain its own tidal response. Water ice abundance in the middle latitudes has a semiannual variation which is similar to the thermal diurnal tide. In addition, the diurnal heating rate of aerosols is calculated and Hough decomposition is performed to estimate the radiative effect of aerosols on diurnal tide.

  PS12-D5-PM2-P-010 (PS12-A006)
 
Modeling the Evolution of Pluto's Ice-Rich Surface
Qiang WEI#+, Yongyun HU
Peking University, China
#Corresponding author: wadew@pku.edu.cn +Presenter

Recent discoveries made available through NASA’s New Horizon mission revealed a new world on Pluto with a plateau of “young” surface. We endeavor to explore various possibilities that may have contributed to this phenomena, including atmospheric condensation, ice sheet evolution, etc.

The first perspective would require a 3D GCM adapted for Pluto’s exceptionally thin atmosphere, while the later one could be studied by introducing an ice sheet model with revised nitrogen ice parameters, gravity and bottom features.

The co-existence of nitrogen- and water-ice on Pluto may hold the key to answering our question. Some initial simulations have revealed that nitrogen ice sheet could deform to flatten out under its own weight, smoothing craters. Though awaiting further verification, model experiments suggested that this mechanism is workable on a timescale of a million years.

  PS12-D5-PM2-P-011 (PS12-A009)
 
On the Detection of Carbon Monoxide as an Anti-Biosignature in Exoplanetary Atmospheres
Yuwei WANG1#+, Feng TIAN2, Yongyun HU1
1 Peking University, China, 2 Tsinghua University, China
#Corresponding author: wangyuwei@pku.edu.cn +Presenter

Recent works suggest that oxygen can be maintained on lifeless exoplanets in the habitable zones of M dwarfs as the results of photochemical reactions. However, the same photochemical models also predict high concentrations of carbon monoxide (CO) in the corresponding atmospheres. A line-by-line radiative transfer model is used to investigate observation requirements of O2 and CO. We find that abiotically produced O2 is detectable at 0.76 μm, in agreement with previous findings. More interestingly CO in the corresponding atmospheres is also detectable at NIR. We suggest that future missions aiming at characterization of exoplanetary atmospheres consider detections of CO as an anti-biosignature.

  PS12-D5-PM2-P-012 (PS12-A013)
 
Distinguishing Habitable Exoplanet from Planets Rapidly Losing Water Through Observations
Peiyuan ZANG#+, Feng TIAN
Tsinghua University, China
#Corresponding author: zangpy@hotmail.com +Presenter

Habitable Planets by definition are capable of maintaining liquid water on their surfaces. Thus the amount of water vapor in their atmospheres is limited, with the Earth as the only confirmed example. Planets could start to lose their water rapidly when surface temperature is increased above certain threshold, which drives water into the middle atmosphere where photo dissociation readily convert water vapor into hydrogen and oxygen. We used a 1-D line-by-line radiative transfer model (LT model) to calculated reflectance spectra of the Earth and exoplanets losing water more and more rapidly. The exoplanets are modeled using the CESM model by applying enhanced stellar radiation in comparison to that received by the Earth. The results show that the two spectra can be easily distinguishable without considering cloud effects. In this work we will explore the effect of clouds and its impact on the feasibility to distinguish habitable exoplanet from planets rapidly losing water observationally. 

  PS12-D5-PM2-P-014 (PS12-A016)
 
Numerical Simulation of Topographic Effects on Wind Flow Fields Over Mountainous Area of Mae Moh District
Rudklao PAN-ARAM#+, Phurichr VIRYASIRI
Electricity Generating Authority of Thailand, Thailand
#Corresponding author: rudklao@yahoo.com +Presenter

The Regional Atmospheric Modeling System version 6.0 (RAMSv6.0) was applied to study topographic effects on wind flow fields over Mae Moh district of Lampang Province, a mountainous area in northern Thailand. The Mae Moh district is the area where the Thailand largest lignite open mining is located.The operation of lignite mining changes the topography height all times by excavation and land reclamation. In this study the SRTM Digital Elevation Database V4.1 was introduced to use as the terrain height in the model simulation.The computational results are compared against observational meteorological data at monitoring stations of the Electricity Generating Authority of Thailand.The evaluation demonstrates that the numerical simulation values are in good agreement with observational data and the model can capture the diurnal variations in temperature in each hour well, especially in December when the temperature was decreased rapidity. The sensitivity analysis was also conducted to investigate changes in terrain upon temperature and wind fields between using terrain dataset from ATMET website and SRTM Digital Elevation Database V4.1.

  PS15-D5-PM2-P-008 (PS15-A002)
 
Surface Thermophysical Properties Investigation of Asteroid (99942) Apophis
LiangLiang YU1#+, Wing-Huen IP2, Jianghui JI3
1 Macau University of Science and Technology, China, 2 National Central University, Taiwan, 3 Chinese Academy of Sciences, China
#Corresponding author: yullmoon@live.com +Presenter

We introduce a new method combining the 1D thermal physical model with radiative transfer model to analyze asteroid (99942) Apophis' Herschel-far-infrared observations. With this method, we simultaneously derived a best-fit solution for both the average surface thermal inertia and surface density of Apophis , where $\Gamma=800\pm200\rm~Jm^{-2}s^{-0.5}K^{-1}$ and $\rho=1.6\pm0.2\rm~gcm^{-3}$. The high thermal inertia is very similar to that of Itokawa, implying that the most region of Apophis' surface remains unchanged by some mature effects like space weathering, thermal degradation or micrometeorite impacts during the past period after formation. The low surface density indicates a very high surface porosity about $50\%$. While these results are considered together, they reveal a direct evidence of Apophis' rubble-pile interior structure. Based on the derived surface porosity and the deduction of rubble-pile structure, we provide a conservative estimation of Apophis' average porosity to be $41^{+4}_{-11}\%$, bulk density of $\rho_{\rm bulk}=1.9^{+0.35}_{-0.13}\rm~gcm^{-3}$, and mass about $m=2.93^{+0.54}_{0.2}\times10^{10}\rm~kg$. These results are helpful when we attempt to predict Apophis' orbit and potential Earth impact probability more precisely, and seek out a way to artificially avoid the probable impact.

  PS15-D5-PM2-P-009 (PS15-A003)
 
The Analysis of the Different Scattering Laws for the Cellinoid Shape Model
Xiao-Ping LU1#+, Xiang-Jie HUANG1, Wing-Huen IP2, Haibin ZHAO3, Yun-Lin SONG1
1 Macau University of Science and Technology, Macau, 2 National Central University, Taiwan, 3 Purple Mountain Observatory, China
#Corresponding author: xplu@must.edu.mo +Presenter

As an intermediate shape model between the traditional triaxial ellipsoid and convex shape, Cellinoid shape model was first presented by Alberto Cellino, which consists of eight ellipsoidal octants with the constraint that adjacent octants must have two identical semi-axes. Based on this shape model, an efficient algorithm to derive the physical parameters, such as the rotational period, spin axis, and overall shape from either lightcurves or sparse photometric data is developed by Lu et al.[1].  Numerical applications show that the inverse algorithm could derive the best-fit rotational period for the asteroid from several lightcurves observed in one apparition.  Moreover, with more lightcurves observed in various viewing geometries, the algorithm could refine the pole estimate for the asteroid [2]. Additionally, the application of the algorithm based on the cellinoid shape model to the Hipparcos data with the average number of measurements being of the order of 70 per object,  confirms the advantages of cellinoid shape model in applying the sparse photometric data [3]. This will provide an efficient tool of searching the physical parameters for a huge number asteroids, being observed by the ongoing space project, Gaia. With only 3 more parameters than the traditional triaxial ellipsoid, the cellinoid shape model of having the asymmetric morphology could perform efficiently and simulate the real asteroids better. 
In order to improve the inverse algorithm based on the cellinoid shape model in simulating the light scattering, several scattering models including the Lommel-Seeliger law, Lumme-Bowell law, and Muninonen's mathematical formula are applied and numerically compared. By comparing the morphologies of the synthetic lightcurves generated with different scattering models and testing the numerical stability in the inverse process, an appropriate scattering model is selected in the future applications for the algorithm based on the cellinoid shape model.  

References:

1. Lu X.-P. et al.(2014) Earth,Moon and Planet. 112, 73-87

2. Lu X.-P. et al.(2015) Planetary and Space Science. 108, 31-40

3. Lu X.-P. et al.(2016) Icarus. 267, 24-33

  PS15-D5-PM2-P-010 (PS15-A005)
 
Constriants on the Thickness and the Strength of the Surface Material of 433-Eros from Gravity Data
Wei LIU#+, Jianguo YAN, Jean Pierre BARRIOT
Wuhan university, China
#Corresponding author: 874036506@qq.com +Presenter

The Bouguer anomalies over the surface of asteriod 433-Eros indicate indicate that there is a slight deficit of mass located at ends of the asteroid. We explain this deficit as an over-accumulation of ejecta at these locations, due to the rotational dynamic of the body. We show that the thickness of the deposit(and so the Bouguer anomaly)is related to the strength of the bulk material of the asteroid, and estimate it.

  PS15-D5-PM2-P-011 (PS15-A015)
 
Rotationally Resolved Polarization Observations of the M-Type Asteroid 16 Psyche
Kang-Shian PAN#+, Wing-Huen IP
National Central University, Taiwan
#Corresponding author: m989005@astro.ncu.edu.tw +Presenter

A survey program of the photometric and polarimetric properties of the M-type asteroids has recently been established at the Lulin Observatory mking use of the multi-wavelength photopolariter called TRIPOL.The first step is to observe targets of large brightness. The initial results of the rotationally resolved polarimetric measurements of 16 Psyche and a few other M-type objects are reported here.

  PS18-D5-PM2-P-013 (PS18-A009)
 
The Influences of the Regolith Thickness on the Boulders Distribution Around Moon Crater
Yuan LI1#+, Minggang XIE1, Wing-Huen IP2
1 Macau University of Science and Technology, Macau, 2 National Central University, Taiwan
#Corresponding author: lysongly@sina.com +Presenter

We investigated the size frequency distributions (FFDs) of the boulders ejected from small lunar craters with diameter smaller than 1 km. The sample includes 10 craters of different ages determined by cosmic ray exposure time (Arvidson et al., 1975; Eugster, 1999) and geomorphological consideration (A.T. Basilevsky et al., 2013). It is found that the FFDs do not have clear correlation with either the crater age or the crater size. Instead, the thickness of the regolith could play a significant role in determining the ejecta production and the corresponding FFDs.

  PS18-D5-PM2-P-014 (PS18-A015)
 
Engaging the Global Public by Naming Craters on Mercury
David BLEWETT1#+, Heather WEIR2, Julie EDMONDS3, Keri HALLAU4, Bob HIRSHON5, John HAMEL6, Stacy HAMEL6, Jeff GOLDSTEIN6, Sean C. SOLOMON7, Larry NITTLER7
1 Johns Hopkins University, United States, 2 Science Systems and Applications, Inc., United States, 3 Carnegie Academy for Science Education, United States, 4 Montana State University, United States, 5 American Association for the Advancement of Science, United States, 6 National Center for Earth and Space Science Education, United States, 7 Carnegie Institution of Washington, United States
#Corresponding author: David.Blewett@jhuapl.edu +Presenter

NASA’s robotic MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER)spacecraft made history in March 2011 by becoming the first to orbit Mercury. During the mission, MESSENGER acquired more than 250,000 images and made many other kinds of measurements. To draw international attention to the achievements of the MESSENGER mission, the MESSENGER Education and Public Outreach (EPO) Team initiated a competition to "Name a Crater on Mercury." Five unnamed craters of particular geological interest were chosen by the science team. In accordance with International Astronomical Union (IAU) rules for Mercury, impact craters are named in honor of persons who have made outstanding or fundamental contributions to the arts and humanities. He or she must have been recognized as a historically significant figure in the arts for at least 50 years, and be deceased for at least three years. We were particularly interested in entries honoring people from nations and cultural groups underrepresented in the current list of crater names. From more than 3600 entries received from around the world, the EPO team was able to reduce the number of entries to about 1200. These entries proposed names of 583 different artists who met the contest eligibility criteria. Next, the proposed individuals were grouped into five artistic fields, and each was distributed to experts in the respective field. Each expert reviewed biographical information for approximately 100 artists. They narrowed their list to a top ten, then to a top five by applying a rubric. The final selection was based on the reviewer lists and scores, with at least three finalist names selected from each artistic field. Of the 17 finalists provided to the IAU, the following crater names were selected: Carolan (Irish), Enheduanna (ancient Mesopotamian), Karsh (Armenian-Canadian), Kulthum (Egyptian), and Rivera (Mexican).

  PS18-D5-PM2-P-015 (PS18-A016)
 
International Observe the Moon Night: Engaging a Global Audience in Lunar and Planetary Science and Exploration
Lora BLEACHER1#+, Andrea JONES2, Andrew SHANER3, Brian DAY4, Sanlyn BUXNER2, Matthew WENGER2, Emily JOSEPH2, Pamela GAY5, Suzy GURTON6, Erin WOOD7
1 NASA Goddard Space Flight Center, United States, 2 Planetary Science Institute, United States, 3 Lunar and Planetary Institute, United States, 4 Wyle Laboratories, Inc., United States, 5 Southern Illinois University Edwardsville, United States, 6 Astronomical Society of the Pacific, United States, 7 University of Colorado Boulder, United States
#Corresponding author: Lora.V.Bleacher@nasa.gov +Presenter

International Observe the Moon Night (InOMN) is a worldwide celebration held annually since 2010. One day each year, everyone on Earth is invited to unite to observe and learn about the Moon and to share personal connections to Earth’s nearest neighbor. Through InOMN, the public is inspired to learn more about lunar and planetary science and exploration, and is provided with the resources and opportunities to do so– and to see themselves as citizens of the solar system. InOMN celebrates its 7th anniversary on 08 October 2016.

Approximately 75,000 people in 55 countries participate in InOMN annually. Events are held at research centers, museums, planetaria, schools, universities, observatories, libraries, parks, businesses, and backyards. While having a telescope or binoculars on hand to view the Moon is ideal, it is not required – making this an easy event for everyone, including people in developing countries, to participate in.

Volunteer hosts register their events at http://observethemoonnight.org. The InOMN Coordinating Committee, led by the Lunar Reconnaissance Orbiter team, provides online resources, training, and evaluation. Data show that: InOMN is as an easy-to-implement event for many different types of organizations and segments of the global population; InOMN provides opportunities to observe and learn about planets and other celestial objects, in addition to the Moon; participants are motivated to learn more about lunar and planetary science and exploration after attending an event.

Participation in InOMN can help organizations: reach new–and underserved–audiences with lunar and planetary science and exploration content; build public interest and confidence in observing the solar system with telescopes and the naked eye; build and sustain public interest in exploration of the solar system. InOMN transforms citizens of the Earth… into citizens of the solar system. Join the global celebration by hosting or volunteering to help with an event!

  PS18-D5-PM2-P-016 (PS18-A017)
 
Moments of Inertia of Phobos with Inhomogeneous Internal Structure
Koji MATSUMOTO1#+, Hitoshi IKEDA2
1 National Astronomical Observatory of Japan, Japan, 2 Japan Aerospace Exploration Agency, Japan
#Corresponding author: koji.matsumoto@nao.ac.jp +Presenter

The origin of Phobos is still an open issue. It may be either captured asteroid or formed from a disk of impact ejecta produced by a giant impact. Although it is not straightforward to determine the origin from internal structure alone, it will place important constraints. One of the key parameters related to the internal structure is moments of inertia (MOI). Phobos’s MOI can be determined from amplitude of short-period forced libration and degree 2 gravity coefficients. Currently, the libration amplitude is estimated to be 1.09+/-0.01 degrees by analyzing multiple image data (Oberst et al., 2014). Although the degree 2 gravity coefficients are estimated from tracking data of Mars Express on its close flyby at Phobos, they are not solved for at sufficient accuracy (Pätzold et al., 2014). Axial difference of MOI can be constrained by the libration amplitude, but currently MOI of Phobos is not known. The observed libration amplitude is consistent with homogenous mass distribution of Phobos, but local mass anomalies cannot be ruled out (Rambaux et al., 2012). Phobos’s bulk density of 1.86±0.013 g/cm3 (Willner et al., 2014) is lower than most of the samples of carbonaceous material, which requires porosity and/or light elements like water ice. Here we consider relatively simple two-layer internal structure and assume that ice water or porosity is confined in either layer, and calculate how much MOI deviate from the value for homogeneous body if such an inhomogeneity existed. It is found that the MOI deviation is smaller than 16-17%. A 10% accuracy will not be sufficient, and it is required to achieve at least a few percent of MOI accuracy in order to detect it. To this end, the required accuracies for the libration amplitude and the degree 2 gravity coefficients are also a few percent.

  PS19-D5-PM2-P-013 (PS19-A003)
 
What Color and Brightness is the Moon?
Yunzhao WU#+, Zhenchao WANG, Xiao TANG, Xiaomeng ZHANG, Yuan CHEN, Wei CAI
Nanjing University, China
#Corresponding author: yunzhaowu@qq.com +Presenter

The Moon’s brightness and color is a simple but important problem. The answer to this question has many implications. The accurate measurement of the lunar reflectance spectrum is vital for answering it. Many instruments such as from the Earth, Clementine, Kaguya, Chang’E (CE) 1-3, Chandrayaan-1, and LRO-WAC measured the moonlight. This paper introduced the CE-1 Interference Imaging Spectrometer (IIM) and CE-3 VNIS in situ reflectance products and the large amounts of comparison among these missions.

Through four-year research, we finished the hyperspectral and high spatial resolution mosaic for IIM at standard geometry which were processed using the pipeline described in [Wu et al., 2013]. The boundaries of the mosaic between adjacent orbits are invisible. The IIM reflectance of the same location with multiple observations match very well (RMS< 0.01). Both the seamless mosaic and consistent reflectance demonstrate the quality of the photometric model and reflectance products of IIM. Through two-year research, we finished the CE-3 in situ reflectance. By coparison with data among different nations, large difference exist among these data. All the orbital reflectance is much smaller than the Apollo sample reflectance. LRO WAC reflectance is the largest and reddest. The absolute reflectance of IIM compared to OP2C1 M3 reflectance and CE-3 in situ reflectance, and both are much larger than the OP1B M3 reflectance.

We would like to provide users all the data including both mosaic and individual orbits for IIM and VNIS. For individual orbits they can be used to compare the absolute reflectance of the same location with multiple observations. The seamless mosaic and VNIS reflectance can have several uses such as elements, geology, comparison of lunar irradiance model and absolute reflectance, calibration for Earth observation sensors and separation of basaltic units. Users are welcome to contact us for these products.

  PS19-D5-PM2-P-014 (PS19-A006)
 
High Resolution Lunar Mascon Density Structure Revealed by Grail Gravity
Jianguo YAN1#+, Zhang YI2
1 Wuhan university, China, 2 China Earthquake Administration, China
#Corresponding author: jgyan_511@163.com +Presenter

In the history of the moon exploration, the most amazing achievement is that some mass concentrated areas were found on the near side of the moon1, 2. These mass concentrated areas, which are referred to mascons, are usually covered with a positive gravity anomaly peak, and surrounded by negative gravity anomalies with low geographical elevation1-7. Here we proposed a gravity inverse method including geological constraint to obtain density structure of the lunar mascons. The method was implemented in spherical coordinates and validated with simulation test. Using this method we obtained high resolution density anomaly structure of lunar near side maria mascons basins and far side highland mascons. The high resolution depth information and density anomalies structure of the lunar mascons are presented for the first time. By comparing the near side maria mascons with far side mascons, we found all the mascons have an annulus density structures in their shallow stratums; the mascon depth information also indicates that the mascon depth on lunar far side is much deeper than that on the near side. These results indicate various origination mechanism between nearside and farside mascons.

  PS19-D5-PM2-P-015 (PS19-A012)
 
Initial Observation of the Lunar Ionosphere from Radio Occultation Based on the Service Module of Circumlunar Return and Reentry Spacecraft
Mingyuan WANG1#+, Songtao HAN2, Jinsong PING1
1 Chinese Academy of Sciences, China, 2 Beijing Aerospace Control Center, China
#Corresponding author: wangmy@nao.cas.cn +Presenter

The circumlunar return and reentry spacecraft is an experimental unmanned lunar mission which was launched on October 23th 2014. After the experiment of reentry technology, the service Module of the circumlunar return and reentry spacecraft entered lunar orbit by January 13th 2015. During this extend period, we performed radio occultation experiment with dual frequency (S and X) to further understand themorphology of the lunar ionosphere. Radio occultation experiment is mainly used in the detection of theeffects produced on the radio wave transmitted from the spacecraft to the Earth when it crosses the atmosphere. During the radio wave transmission from the satellite to an Earth station, the wave amplitude and phase is modified by the medium of propagation. The modifications are correlated to the physical parameters (especially electron density) of the medium. The electron density profile measured in our experiment is in agreement with the result of Luna 19 and 22.

  PS19-D5-PM2-P-016 (PS19-A013)
 
Development of the New Broadband Seismometers for Moonquake Observation
Ryuhei YAMADA1#+, Hiroaki SHIRAISHI2, Kazuyoshi ASARI1, Tanguy NEBUT3, Philippe LOGNONNE3, Hideo HANADA1, Satoshi TANAKA2
1 National Astronomical Observatory of Japan, Japan, 2 Japan Aerospace Exploration Agency, Japan, 3 Institute de Physique de Globe de Paris, France
#Corresponding author: r.yamada@nao.ac.jp +Presenter

Through the Apollo lunar seismic observation, we have obtained much information about lunar seismic activity and the interior structure. On the other hand, the observed waveforms of moonquakes were disturbed very much due to scattering caused by lunar surface structure, and it makes hard to identify arrivals of lunar seismic phases. Yamada et al., (2015) describes that we can observe clearer waveforms not affected by the scattering in the frequency range lower than 0.1 Hz whose wavelength is longer than the surface fractured structure. The Apollo seismometers were operated in the limited frequency range, and the seismic data were not available in the low frequency range. The moonquake observation in broadband range is important topic for future lunar seismic experiments.    

We developed two types of new broadband seismometers for future moonquake observations. The seismometers were based on the small sized short-period seismometer which can be loaded on the hard landing probe; penetrator. One is the simple type of the broad-band seismometers, which is constructed only by attachment of the feedback control circuit to the short-period sensor. Another is the installation of capacitive displacement transducer, in which capacitor plates are fitted to both ends of the pendulum and the case. In this type, we can detect ground motions from variation of capacitances caused by displacement of the pendulum.

We describe the designs and performances of two broadband seismometers, and we show the expected scientific results on the future missions. As the performance tests, we investigated the frequency characteristics and response to ground motions of the seismometers in Esashi Earth Tides Station. The STS-2 broadband seismometer was applied as the reference sensor to investigate the responses to small ground motions in the low frequency range. In this presentation, we will report the current status of development with emphasis on the results of the seismic observation tests.

  PS19-D5-PM2-P-017 (PS19-A016)
 
Research on Illumination Characteristic of Aristarchus Plateau by Using DEM Data and Lunar Ephemeris
Jidong ZHANG1#+, Jinsong PING2, Zhiguo MENG3, Wenxiao LI2, Mingyuan WANG2, Rui ZHAO1
1 Jilin University, China, 2 Chinese Academy of Sciences, China, 3 National Astronomical Observatory, China
#Corresponding author: zhangjd14@mails.jlu.edu.cn +Presenter

We analyze the illumination characteristic of Aristarchus plateau with the high resolution DEM data and NASA JPL DE405 lunar ephemeris.We use the NOVAS software to calculate the location of lunar and sun and take the libration into consideration. We calculate the height angle of sun and analyze the topographic effect with a high temporal resolution(3h). We also consider the illumination below the horizon. We generate illumination fraction maps with the resolution of 0.01° for the year of 2015 and the resolution of 0.1° in 1, 9.3, 18.6 and 30 years for Aristarchus plateau. The results show that illumination characteristic is of great association with the topographic feature. The illumination fraction of this region is mostly between 29% and 51%, the maximum and minimum value are 51.32% and 18.07%, respectively. The region with high elevation will enjoy more illumination compare with the low-lying areas. the bottom of Aristarchus crater and Herodotus crater will be illuminated greater nearly 40% than the edge in one year, which may make a great geological condition differences of this region. The illumination characteristics of crater are of special significance to study the evolution of the lunar exploration and worth to further study.

  PS19-D5-PM2-P-018 (PS19-A019)
 
Regolith: Origin and Evolution on Airless Bodies
Jeffrey PLESCIA#+, Andy RIVKIN, Rachel KLIMA
Johns Hopkins University, United States
#Corresponding author: jeffrey.plescia@jhuapl.edu +Presenter

The Johns Hopkins University Applied Physics Laboratory SSERVI team (VORTICES) has been examining the processes that are involved in the formation and evolution of regoliths on airless bodies (the Moon and asteroids). The research is a combination of experimentation, modeling, and validation of models using spacecraft data. Key questions include an analysis of the relative rates of mechanical disruption of bedrock and boulders versus thermal fatigue. Modeling and experimental results have shown that thermal fatigue (weakening) of surface material is a significant effect. Thermal fatigue is particularly relevant to asteroids where impact speeds are low with respect to the Moon. The regolith is ultimately derived from the bedrock that must be broken up into fragments by relatively large impacts that can in turn be whittled down to regolith-size material. We have been examining boulder population data from orbital and surface images in order to understand the characteristics of the starting population and the extent to which that varies across a body or between bodies. Experimental studies have been conducted to determine the thermal characteristics of regolith and the parameters that influence the conductivity and propagation of heat. The thermal properties of the upper few mm of the regolith are critical to understand as that material is what is observed by remote sensing data. Thermal properties of the regolith at cryogenic temperature have been shown to be very different from those at non-cryogenic temperatures, in turn changing the understanding of how heat propagates. In addition to macro-scale processes of regolith evolution, we have examined the phenomena of space weathering caused by micrometeorite impact and solar wind interaction.

  PS23-D5-PM2-P-009 (PS23-A002)
 
Slope and Roughness Characteristics of Galilean Moons Derived from High-Resolution Images
Shoko OSHIGAMI1#+, Naoyuki HIRATA2, Jun KIMURA3, Noriyuki NAMIKI4
1 Kogakuin University, Japan, 2 Kobe University, Japan, 3 Tokyo Institute of Technology, Japan, 4 National Astronomical Observatory of Japan, Japan
#Corresponding author: kt13567@ns.kogakuin.ac.jp +Presenter

Topographic data is fundamental information to investigate geology at various scales. The Galileo spacecraft has obtained high-resolution images of the Galilean satellites at a scale up to approximately ten meters per pixel, which provide an insight into diverse geologies and surface materials associated with tectonics, cratering, and sublimation. Ten-meter scale topography also could be essential for designing radar sounder, laser altimeter, and lander to detect putative subsurface oceans on Jovian icy satellites. Detection of putative subsurface oceans is regarded as one of top priorities for planetary exploration. Nevertheless, no quantitative topographic data at the scale has yet been obtained, except for the surface of Europa. We reexamined high-resolution images obtained by the SSI camera onboard the Galileo spacecraft using stereo image (SI) analysis and photoclinometry (PC).

As for SI analysis, we used Integrated Software for Imagers and Spectrometers (ISIS3) produced by USGS to calibrate the SSI raw images radiometrically and perform bundle adjustment. Then we applied NASA’s Ames Stereo Pipeline software to compute DEMs. PC uses apparent brightness to estimated slope at each pixel, assuming a photometric function. We applied a photometric function that fits lunar-like surface. Roughness is defined as the Allan deviation of height differences between two points separated by a given distance (window length).

As a result, we obtained the slope histograms and roughness from SI analysis and PC. We found that most of Ganymede and the region of Callisto showing abundant knobs appear to be very rough surfaces as steep as 10 to 30º, while Europa and the region of Callisto without knobs mostly appear to be smoother than 10º. These results are far from previous estimates based on topographic data with the lower resolution. Also, this implies that instrument performances are expected to be strongly affected by the steep slopes in the former areas.

  PS23-D5-PM2-P-010 (PS23-A003)
 
Lunar/Planetary Rover Visualization Scheme Using Web Interface and Stereo Topography
Shih-Yuan LIN#+, Jihn-Fa JAN, Li-Yun TSAI
National Chengchi University, Taiwan
#Corresponding author: syl@nccu.edu.tw +Presenter

Rover navigation over planetary/lunar surface became one of the most significant technical issues for the planetary exploration. In order to minimize risk on route planning as well as to produce the best possible scientific outcome, the high precise determination of rover positioning and visualization are crucial. For that purposes, the integration of planetary rover's local route with the geodetically controlled topographic data sets was applied in this study. The test area was set in Martian Eberswalde Crater which was once proposed as the landing site of Mars Science Laboratory. The high accuracy DTM and ortho image from HRSC, CTX and HiRISE stereo imagery were generated based on algorithm proposed by Kim et al. (2013) and co-registered by surface matching routine (Lin et al., 2012). By integrating multiple resolution DTMs of rover routes throughout Web Graphics Library (WebGL), the constructed system demonstrated the potentials for interactive route planning, near real time scientific interpretation by multiple research teams and the useful approach for public interactions. In future the 3D information extracted from rover vision system will be integrated for wide range of applications.

  PS23-D5-PM2-P-011 (PS23-A005)
 
Analysis of Dark Slope Streaks on Mars Based on Multitemporal Imagery and Digital Elevation Models Derived from HRSC Data
Bjoern SCHREINER1#+, Stephan VAN GASSELT2, Jan-Peter MULLER3, Panagiotis SIDIROPOULOS3
1 Freie Universitaet Berlin, Germany, 2 University of Seoul, South Korea, 3 University College London, United Kingdom
#Corresponding author: bjoern.schreiner@fu-berlin.de +Presenter

Recurring slope lineae (RSL) on Mars are dark and narrow downhill orientedsurface features found in equatorial regions (1) associated with water or hydrated salt flows (2). On the other hand there are Dark Slope Streaks which seem to be dry avalanches on dust covered slopes (3). The origin of both ist still under discussion. We found linear features in eastern Noctis Labyrinthus region (6°S, 265°E) with lengths of up to several kilometres and lateral extensions of 20-30 metres. As described by (4), RSL fade and recur in the same location over multiple Mars years. Similarily, Dark Slope Streaks form on at least annual to decade-long timescales (5). During 10 years of HRSC observation time (2005-2015) several linear features in Noctis Labyrinthus changed in visibility. Slope parameters and seasonal illumination conditions are investigated based on a digital elevation model derived from HRSC data. Furthermore we modelled corresponding downslope particle flows originating from point sources. For large datasets a feature identification is presented which involves spatial filtering in conjunction with elevation data analysis.

The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n ° 607379.

References:

1.  McEwen, A.S., et al. (2014): Recurring slope lineae in equatorial regions of Mars. Nat. Geosci 7: 53-58.

2. Ojha, L. et al. (2015): Spectral evidence for hydrated salts in recurring slope linear on Mars. Nat. Geosci, DOI:10.1038/NGEO2 546.

3. Sullivan, R. et al. (2001). Mass Movement Slope Streaks Imaged by the Mars Orbiter Camera. J. Geophys. Res., 106(E10), 23,607–23,633.

4. McEwen, A.S., et al. (2011): Seasonal Flows on Warm Martian Slopes. Science, Vol. 333, Issue 6043, pp. 740-743.

5. Malin, M.C.; Edgett, K.S. (2001). Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission. J. Geophys. Res., 106(E10), 23,429–23,570.

  PS23-D5-PM2-P-012 (PS23-A011)
 
Digital Terrain Models on the Basis of MRO CTX Data and MEX HRSC Data
Alexander DUMKE#+
Freie Universität Berlin, Germany
#Corresponding author: dumke@zedat.fu-berlin.de +Presenter

In planetary surface sciences, digital terrain models (DTM) are paramount when it comes to understanding and quantifying processes. In this contribution an approach for the derivation of digital terrain models (DTM) from stereo images of the NASA Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) are described. CTX consists of a 350 mm focal length telescope and 5000 CCD sensor elements and is operated as pushbroom camera. It acquires images with ~6 m/px over a swath width of ~30 km of the Mars surface [1]. Today, several approaches for the derivation of CTX DTMs exist [i. e. 2, 3, 4]. The discussed approach here is based on established software and combines them with proprietary software as described below.

The main processing task for the derivation of CTX stereo DTMs is based on six steps: (1) First, CTX images are radiometrically corrected using the ISIS software package [5]. (2) For selected CTX stereo images, exterior orientation data from reconstructed NAIF SPICE data are extracted [6]. (3) In the next step High Resolution Stereo Camera (HRSC) DTMs [7, 8, 9] are used for the rectification of CTX stereo images to reduce the search area during the image matching. Here, HRSC DTMs are used due to their higher spatial resolution when compared to MOLA DTMs. (4)  The determination of coordinates of homologous points between stereo images, i.e. the stereo image matching process, consists of two steps: first, a cross-correlation to obtain approximate values and secondly, their use in a least-square matching (LSM) process in order to obtain subpixel positions. (5) The stereo matching results are then used to generate object points from forward ray intersections. (6) As a last step, the DTM-raster generation is performed using software developed at the German Aerospace Center, Berlin. Whereby only object points are used that have a smaller error than a threshold value.

References:

[1] Malin, M. C. et al., 2007, JGR 112, doi:10.1029/2006JE002808 [2] Broxton, M. J. et al., 2008, LPSC XXXIX, Abstract#2419 [3] Yershov, V. et al., 2015 EPSC 10, EPSC2015-343 [4] Kim, J. R. et al., 2013 EPS 65, 799-809 [5] https://isis.astrogeology.usgs.gov/index.html [6]http://naif.jpl.nasa.gov/naif/index.html [7] Gwinner et al., 2010, EPS  294, 543-540 [8] Gwinner, K. et al. EPSC 10, EPSC2015-672 [9] Dumke, A. et al., 2008, ISPRS, 37, Part B4, 1037–1042

  PS23-D5-PM2-P-013 (PS23-A013)
 
The Investigation of SHARAD Profiles Over Martian Lobate Debris Aprons
Hyun-Seob BAIK1,2#+, Kwang-Eun KIM2
1 University of Science & Technology, South Korea, 2 Korea Institute of Geoscience & Mineral Resources, South Korea
#Corresponding author: nairalsaif1116@gmail.com +Presenter

The Shallow Subsurface Radar (SHARAD), a radar sounding radar on the Mars Reconnaissance Orbiter has produced high valuable information about subsurface of Mars. Compared with the precedent Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on Mars Express, it possesses the better vertical resolution consequently more reliable capability to mine subsurface layering up to tens of meters, although its penetration depth is not as far below as MARSIS. Thus SHARAD has been successfully used to observe complicate substructures of Mars polar deposit and some geomorphic features involving possible subsurface ice body such as pedestal crater. However over the highly expected potential ice layering features in large scale such as Medusa Fossae Formation, it failed to trace clear interfaces. 

In this study we summarized all SHARAD profiles over Martian Lobate debris aprons (LDAs) where significant arguments about their origins are undergoing.  As the results, clear layers probably originated between water ice and rock were only identified in very small number of areas such as Euripus Mons. We integrated SHARAD profiles over all mid latitude LDAs into GIS. These will be demonstrated together with several radargram structures. After all, it appeared the distributions and radargram profiles by SHARAD are not sufficient enough to support wide distributions of underlying water ice and the glacial origin of LDA.