PPS05-01

会場:106

時間:5 月 27 日 14:15-14:30

火星大気散逸探査（のぞみ後継機）のミッション計画とシステム検討
Examination of Mission Strategy and Spacecraft System to Study Martian AtmosphericEscape松岡 彩子 1∗ ; 関 華奈子 2 ; 寺田 直樹 3 ; 横田 勝一郎 1 ; 山崎 敦 1 ; 阿部 琢美 1 ; 今村 剛 1 ; 川勝 康弘 1 ;二穴 喜文 4 ; 平原 聖文 2 ; 石坂 圭吾 5 ; 熊本 篤志 3 ; 栗原 純一 7 ; 中川 広務 3 ; 坂野井 健 6 ; 田口 真 8 ;小郷原 一智 9
MATSUOKA, Ayako1∗ ; SEKI, Kanako2 ; TERADA, Naoki3 ; YOKOTA, Shoichiro1 ; YAMAZAKI, Atsushi1 ;ABE, Takumi1 ; IMAMURA, Takeshi1 ; KAWAKATSU, Yasuhiro1 ; FUTAANA, Yoshifumi4 ; HIRAHARA, Masafumi2 ;ISHISAKA, Keigo5 ; KUMAMOTO, Atsushi3 ; KURIHARA, Junichi7 ; NAKAGAWA, Hiromu3 ; SAKANOI, Takeshi6 ;TAGUCHI, Makoto8 ; OGOHARA, Kazunori9
1

宇宙航空研究開発機構 宇宙科学研究所, 2 名古屋大学 STE 研, 3 東北大学理学部, 4 IRF スウェーデン, 5 富山県立大学工学部, 6 東北大学理学部惑星プラズマ大気研究センタ, 7 北海道大学理学部, 8 立教大学理学部, 9 滋賀県立大学工学部
1
ISAS/JAXA, 2 STEL, Nagoya Univ., 3 Dept. Geophys., Grad. Sch. Sci., Tohoku Univ., 4 IRF, Sweden, 5 Toyama Pref. Univ.,
6
Planet. Plasma Atmos. Res. Cent., Tohoku Univ., 7 Cosmosciences, Hokkaido Univ., 8 College of Science, Rikkyo Univ.,
9
School of Engineering, The Univ. of Shiga Prefecture
火星の大気の変遷には、太陽風との相互作用が大きく影響したと考えられているが、今現在の火星においてさえ、大気と太陽風との相互作用の物理プロセスは明らかになっていない。
地球と異なり、現在の火星は惑星固有の磁場を持たない。その結果、太陽風は低い高度にまで達し、火星の大気と直接相互作用して、火星大気の一部は散逸される。この過程は、長い間には火星大気の組成を変化させるまでの作用を及
ぼし、火星大気や、ひいては地上・地下の二酸化炭素（ドライアイス）や水・氷の変遷に大きく影響した可能性があると考えられている。大気散逸の様子は、太陽活動や太陽との距離によって影響を受けるため、大気の長期的な変遷を考えるためには、様々な太陽の状態について相互作用の働きを知らなければならない。
我々は、2011 年 12 月に JAXA 宇宙科学研究所理学委員会において火星大気散逸探査検討ワーキンググループを発足させた。このワーキンググループは、大気散逸に焦点を当て、２つのオービターによって散逸の全体像とプロセスを同時に観測することを検討している。１つのオービター（親衛星）によって、大気散逸が起きているその場のプラズマや中性粒子の観測、散逸する大気等から発せられる光をリモートで撮像し、もう１つのオービター（子衛星）によって同時に太陽風をモニターするというものである。大気散逸の物理プロセス、グローバルな全体像、物理プロセスを決める太陽風のモニターを同時に行うことは、複数衛星によって初めて可能となる、真に大気散逸の全容解明に迫る観測である。
現在我々は、2024 年頃の太陽活動極大期における火星観測を行う大気散逸観測オービターの実現に向けて、サイエン
ス・観測機器・衛星の検討を行っている。科学目標の定量的・具体的な策定、それを達成するために必要な観測機器技術、計画を実現させるための衛星システムおよび軌道計画を検討している。 検討内容の報告と、今後の開発計画を発表する。
キーワード: 火星, 惑星大気, 太陽風, 惑星磁場, プラズマ
Keywords: Mars, Planetary atmosphere, Solar wind, Planetary Magnetic Field, Plasma

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PPS05-02

会場:106

時間:5 月 27 日 14:30-14:50

MARS PLATE-TECTONIC-BASEMENTMARS PLATE-TECTONIC-BASEMENT
Dohm James1∗ ; 丸山 茂徳 2 ; 宮本 英昭 1 ; 新原 隆史 1
DOHM, James1∗ ; MARUYAMA, Shigenori2 ; MIYAMOTO, Hideaki1 ; NIIHARA, Takafumi1
1
1

東京大学 総合研究博物館, 2 東工大
UMUT, 2 TiTech

Introduction: The Hadean-age-equivalent (>4.0 Ga) Martian basement complex has heretofore been difficult to characterize.
This is due to extensive modification by the Late Heavy Bombardment and subsequent impacts, as well as chemical alterationof the primary rocks (including weathering rinds, clay minerals, Al/Fe oxides/hydroxides, sulfates, and evaporite deposits). Obscuration of a felsic basement includes erosion of the terrain predominantly through wind and water activity, as well pervasive
mantling by wind- (e.g., aeolian), water- (e.g., fluvial, alluvial, colluvial, glacial, periglacial), and volcanic- (airfall deposits, lava
flows materials, fine-grained volcanic spherules transported by wind) related materials.
Yet, unlike the Hadean rocks that have been obliterated on Earth, the Hadean-age-equivalent ancient Martian basement is stillpreserved. This is because an Earth-like phase of Mars, including an active dynamo and hypothesized plate tectonism, terminatedsufficiently early in its evolutional stage to archive early Mars rocks, early solar system history, and possibly evidence of earlylife. New evidence for plate tectonism includes a systematic, spatial arrangement of landforms, referred to as the Claritas subduction zone region that is strikingly similar to the plate-tectonic-modified landscapes of the western US that resulted from plate
migration and subduction, including the subduction of the denser mafic Farallon Plate beneath the lighter felsic North American
Plate. We will present this finding and additional evidence for a Hadean-age-equivalent phase of plate tectonism on Mars and its
implications. For greater details see [1].
[1] Dohm, J.M., Spagnuolo, M.G., Williams, J.-P., Viviano-Beck, C.E., Karunatillake, S., Alvarez, O., Anderson, R.C.,
Miyamoto, H., Baker, V.R., Fairen, A., Mahaney, W.C., Hare, T.M., Robbins, S.J., Niihara, T., Yin, A., Judice, T., Olsen,N., Maruyama, S., 2015. The Mars Plate-Tectonic-Basement hypothesis. 46th Lunar and Planetary Science Conference, Abstract 1741.
Keywords: mars, plate tectonics, basement, felsic

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PPS05-03

会場:A03

時間:5 月 28 日 09:00-09:15

火星大気と表層水の初期進化：同位体組成からの制約
Early Evolution of Martian Atmosphere and Hydrosphere: Constraints from Isotopic
Compositions
黒川 宏之 1∗ ; 黒澤 耕介 2 ; 臼井 寛裕 3
KUROKAWA, Hiroyuki1∗ ; KUROSAWA, Kosuke2 ; USUI, Tomohiro3
1

名古屋大学素粒子宇宙物理学専攻, 2 千葉工業大学惑星探査研究センター, 3 東京工業大学地球惑星科学専攻
Dept. of Phys., Nagoya University, 2 Planet. Explor. Res. Ctr., Chiba Institute of Technology, 3 Dept. of Earth & Planet. Sci.,
Tokyo Institute of Technology

1

現在の火星は極域に少量の氷があるのみの寒冷で乾燥した表層環境を持つ惑星である。一方で、初期の火星は大量の液体の水が存在する温暖な気候であったという証拠が続々と発見されてきている (DI Achille & Hynek, 2010 など)。初期の
火星大気と表層水は天体衝突による大気剥ぎ取りと熱的/非熱的大気散逸によって失われた可能性がある (Lammer et al.,2008) が、その時期と各過程がどの程度寄与したかについてはよくわかっていない。
熱的/非熱的大気散逸は重い同位体が火星大気と表層水に濃集する同位体分別を引き起こす。一方、天体衝突剥ぎ取り
は同位体分別を引き起こすことなく、大気の一部を取り除く。初期の火星大気と表層水の進化は 41 億年前の結晶化年代(Lapen et al., 2010) を持つ火星隕石 Allan Hills 84001(ALH 84001) の記録する揮発性元素同位体組成によって制約できる。
ALH 84001 の記録する 41 億年前の高い水素同位体比 (始原的な水の 2-4 倍の D/H 比、Boctor et al., 2003; Greenwood etal., 2008) は、火星形成後の 4 億年間にその後の時代を上回る大量の水が熱的/非熱的大気散逸によって失われたことを示唆している (Kurokawa et al., 2014)。一方で、41 億年前の希ガス同位体比は分別していない値を示すことから、大気は 41
億年前より最近の時代に失われたと考えられている (Mathew & Marti, 2001; Jakosky & Phillips, 2001)。また、ALH 84001の窒素同位体組成の見積もりは過去の研究によって異なる (Miura & Sugiura, 2000; Mathew & Marti, 2001)。
我々は天体衝突剥ぎ取りと熱的/非熱的大気散逸を考慮して、大気と表層水の総量と同位体組成の進化をそれぞれ独立に計算した。まず、確率論的衝突モデル (Kurosawa et al., 2013) を用いて、大気全圧の進化を計算した。天体衝突頻度分布は月クレーターに基づくモデル (Chyba, 1991) を用いた。剥ぎ取り効率は sector blow-off モデル (Vickery & Melosh, 1990)
を用いて計算した。岩石蒸気の運動量はエントロピー法 (Ahrens & O’Keefe, 1972; Kurosawa et al., 2012 など) とフォルステライトの熱力学データ (Sekine et al., 2012) を用いて計算した。次に、得られた大気全圧進化のもとで、熱的/非熱的
大気散逸による微量揮発性元素の同位体比 (D/H, 15 N/14 N, 38 Ar/36 Ar) の進化を計算した。酸素と窒素、アルゴンについては、Jakosky et al. (1994) と Pepin (1994) のイオンピックアップ、スパッタリング、光化学的散逸の散逸率を用いた。
水素の熱的散逸率は酸素の散逸率に律速される (Liu & Donahue, 1976) と仮定した。水素の分別係数は 0.016 を仮定した(Krasnopolsky et al., 1998; Krasnopolsky 2000)。窒素とアルゴンの分別係数は Jakosky et al. (1994) の値を用いた。
大気全圧は隕石重爆撃期に対応する初期数億年の間で数桁減少するが、その後の変化は小さい。窒素とアルゴンの同位体比は大気全圧が減少するに従って増加する。一方、水の主要なリザーバーは表層水であるため、水素同位体比は大気全圧進化とは独立に増加する。我々の計算結果を火星隕石 ALH 84001 に記録された 41 億年前の元素同位体比と比較することにより、我々は火星の大気と表層水の損失は 41 億年以上前から進行していたという仮説を提案する。隕石重爆
撃期の衝突剥ぎ取りによって厚い初期大気が失われた後、熱的/非熱的大気散逸による大気中の窒素と希ガスの同位体分別が進んだ可能性がある。
キーワード: 火星, 大気, 水, 同位体, 天体衝突, 大気散逸
Keywords: Mars, atmosphere, hydrosphere, isotope, impact, atmospheric escape

1/1

PPS05-04

会場:A03

時間:5 月 28 日 09:15-09:30

Spectral observation of mesospheric CO2 ice clouds in the Martian mid-low latitude using
PFS onboard Mars Express
Spectral observation of mesospheric CO2 ice clouds in the Martian mid-low latitude using
PFS onboard Mars Express
佐藤 佑紀 1 ; 笠羽 康正 1∗ ; 青木 翔平 2 ; Giuranna Marco2 ; 中川 広務 1 ; 黒田 剛史 1 ; 佐藤 隆雄 3
SATO, Yuki1 ; KASABA, Yasumasa1∗ ; AOKI, Shohei2 ; GIURANNA, Marco2 ; NAKAGAWA, Hiromu1 ;KURODA, Takeshi1 ; SATO, Takao M.3
1
1

東北大・理, 2 IAPS/INAF, 3 ISAS/JAXA
Tohoku Univ., 2 IAPS/INAF, 3 ISAS/JAXA

Mars is the only known planet where CO2 ice clouds can be observed. CO2 , main component of Martian atmosphere, cancondense and form ’CO2 ice clouds’ in the coldest region; in the troposphere above polar night and in the mesosphere aroundequator. CO2 ice has narrow spectral emission peak feature at 4.3 um. Unfortunately, polar cloud in the lower altitude is below
thick atmosphere and this spectral feature can not be detected by strong CO2 gas absorption. However, mesospheric cloud in
low-mid latitude is enough high. Dayside nadir observation of OMEGA aboard the Mars Express spacecraft first detected suchfeature.
In this study, we attempted to detect the spectral feature of mesospheric CO2 ice clouds in low-mid latitude at 4.3 um band by
Planetary Fourier Spectrometer (PFS) onboard Mars Express. In this wavelength, its spectral resolution is ˜1,000, about 10 times
higher than that of OMEGA. It enables us to resolve the spectral features of CO2 ice clouds with enough resolution to estimate
their particle size comparing with synthetic spectra. We confirmed that PFS could detect this spectral profil on the orbits where
OMEGA detected CO2 ice clouds. In the PFS spectral resolution, we identified two spectral types, i.e., ’single-peak case’ at 4.25
um and ’double-peak case’ at 4.25 and 4.28 um, which were not resolved by OMEGA.
Based on this confirmation, we statistically surveyed the CO2 ice features in all PFS data in 2004-2014 which covers MY
27-32. We identified 272 single-peak cases and 9 double-peak cases. Spatial and seasonal distributions of CO2 ice clouds agreed
with the previous studies. In spatial distribution, CO2 ice clouds were detected in the latitude range of 20 degS to 20 degN andthe longitude range of 100 degW to 30 degE and around 170 degE. In seasonal variation, almost all of CO2 ice clouds weredetected just after spring equinox (Ls : 0-30 deg).
In these samples, the spectral peak in the single-peak case and the first peak of double-peak case was centered at 4.252 um.
From this observed feature, we derived the typical particle size of CO2 ice clouds by the comparison with the synthetic spectra
derived by a radiative transfer model with the assumption that cloud particles were made of pure CO2 ice and had sphericalshape. Refractive index of CO2 ice is from experimental one. Although the observed single-peak feature was reproduced by
the model, the peak wavelength appeared at ˜4.27 um, shifted to 0.02 {Y=mu}m longer position than the observed one. Suchshift of the peak position could not be reproduced by various particle parameters, including radius, size variance, and column
density. In addition, the synthetic spectra could not reproduce the double-peak structure observed by PFS. We proposed threepossible cases to explain these discrepancies; (1) the uncertainty of the refractive indices, (2) non-spherical particle shape, and(3) different core material in CO2 ice. For (1), we simply assumed that the model refractive index could be shifted 20 nm toward
shorter wavelength. After that, we got satisfied agreement between the observed and model spectrum. Based on the matching ofboth spectrum, effective radii of observed CO2 ice cloud were constrained in the range between 0.63 to 1.0 um. This is the firstquantitative estimation of the CO2 ice clouds using 4.3 um feature of CO2 ice. The effective radii obtained by our model follows
the line of CRISM observation (0.5-2.0 um) but slightly small compared with that of previous works. For (2) and (3), they canpotentally produce double-peak features observed by PFS. It means that non-spherical haze with a core material might be actual
characteristics of the Martian mespheric CO2 ice cloud.

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PPS05-05

会場:A03

時間:5 月 28 日 09:30-09:45

氷上のサイクリックステップ:火星北極冠のスパイラルトラフ形成機構解明のためのアナログ実験と理論解析
Cyclic step on ice: experiments and theoretical study aiming to spiral troughs on Mars’
North Polar ice cap
横川 美和 1 ; 泉 典洋 2∗ ; 内藤 健介 3 ; 山田 朋人 2 ; Greve Ralf4
YOKOKAWA, Miwa1 ; IZUMI, Norihiro2∗ ; NAITO, Kensuke3 ; YAMADA, Tomohito2 ; GREVE, Ralf4
1

大阪工業大学情報科学部, 2 北海道大学工学研究院, 3 イリノイ大学アーバナ・シャンペーン校, 4 北海道大学低温科学研
究所
1
Faculty of Information Science and Technology, Osaka Institute of Technology, 2 Faculty of Engineering, Hokkaido University,
3
University of Illinois, at Urbana-Champaign, 4 Institute of Low Temperature Science, Hokkaido University

The spiral troughs observed on the Mars’ North Polar Layered Deposits (NPLD) contain a detailed stratigraphic record of
surface processes in Mars’ recent polar history. SHARAD radar data showed that the troughs have migrated towards the northduring the accumulation of the uppermost ˜600 m of NPLD, and Smith et al. (2013) concluded that the spiral troughs should bea kind of cyclic steps formed by katabatic wind blowing on the ice cap. Cyclic steps are spatially periodic bedforms where eachwavelength is delineated by an upstream and downstream hydraulic jump. They migrate upstream keeping the same wavelength.
Cyclic steps have been reported from various environments on the Earth, such as fluvial and deep-sea settings, and in various bed
materials, such as bedrock, non-cohesive sediments, and cohesive sediments. While the formation of cyclic steps on bedrock or
beds composed of sediment is a mechanical process, the formation of cyclic steps on ice is not only a mechanical but thermodynamic process. There have not been many studies on the thermodynamics of the formation of cyclic steps on ice to authors’knowledge. In this study, we conducted a series of experiments on the formation of cyclic steps on ice due to flowing water overit. In addition, we performed a linear stability analysis of the water-ice interface and show that the formation of cyclic steps canbe explained by the results of the analysis in part.
The experiments were conducted in the cold chamber owned by the Institute of Low Temperature Science, Hokkaido University. We have conducted 8 cases of experiments by the use of the experimental apparatus that consists of a flume, a cooling systemof the flume, and a circulating system of water. We kept the ice temperature to be below zero degrees in Celsius, the flowing
water temperature to be from 0.2 to 2 degrees in Celsius, and the room temperature to be about 5 degrees in Celsius. As a result,
it is found that trains of steps are formed when the Froude number is larger than a value around unity. Those steps are associatedwith hydraulic jumps, and steps mostly migrate in the upstream direction. Based on these diagnoses and the morphologic feature,these steps can be evaluated as cyclic steps on ice bed.
We performed a linear stability analysis on instability of interface between flowing water and ice, and made physical explanation of the formation of cyclic steps. According to the results of the analysis, the interface becomes unstable when the Reynolds
number is relatively large under the condition that the heat flux from ice is sufficiently weak, that is to say, the temperature at
the ice bottom is not so low, and the ice thickness is sufficiently large. In addition, the unstable region in the wave number Reynolds number plane hardly depends on the heat transfer coefficient of air normalized by the heat diffusivity of water and theflow depth.
We compared the results of experiments and the analysis, and found that the experimental data fall on the unstable region bothin the wave number - Reynolds number plane and the wave number - Froude number plane where interfacial instability takes
place. This indicates that at least the experimental results are consistent with the analytical results. The critical Froude number
derived from the analysis is approximately unity in the range of small slope angles, and slightly increases with the slope angle.
In the experiments, cyclic steps are not formed in the case of the Froude number smaller than unity while cyclic steps are formed
in all the case of the Froude number larger than unity. In terms of the critical Froude number, the experimental results are well
explained by the analysis.
キーワード: サイクリックステップ, 氷床, スパイラルトラフ
Keywords: cyclic step, ice, spiral troughs

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PPS05-06

会場:A03

時間:5 月 28 日 09:45-10:00

火星生命探査の意義と計画
Life search plan on Mars surface and the significance山岸 明彦 1∗ ; 佐藤 毅彦 2 ; 宮川 厚夫 1 ; 吉村 義隆 3 ; 本多 元 4 ; 佐々木 聡 5 ; 今井 栄一 4 ; 臼井 寛裕 6 ;宮本 英昭 7 ; 藤田 和央 8
YAMAGISHI, Akihiko1∗ ; SATOH, Takehiko2 ; MIYAKAWA, Atsuo1 ; YOSHIMURA, Yoshitaka3 ; HONDA, Hajime4 ;SASAKI, Satoshi5 ; IMAI, Eiichi4 ; USUI, Tomohiro6 ; MIYAMOTO, Hideaki7 ; FUJITA, Kazuhisa81

東京薬科大学生命科学部, 2 宇宙科学研究所, 3 玉川大学農学部, 4 長岡科学技術大学, 5 東京工科大学, 6 東京工業大学, 7
東京大学, 8 宇宙航空研究開発機構
1
Tokyo Univ. Pharm. Life Scie., Dep. Applied Life Scie., 2 ISAS/JAXA, 3 Tamagawa Univ., 4 Nagaoka Inst. Tech., 5 Tokyo Univ.
Tech., 6 Tokyo Inst.Tech., 7 The Univ. Tokyo, 8 JAXA
近年の探査により火星の描像は大きく変化し, 現在も動的な火星という描像が誕生した．そして火星で液体の水の存在が確実視される場所として, リカリング・スロープ・リニア (RSL) と呼ばれる場所がある．本計画は, 火星史における現在も動的な火星という描像を検証し, 特に現存する生命の最も可能性の高い場所で生命の存否を検証する．
1970 年代のバイキング探査では, 3 つの生命代謝反応を測定する実験を行った．3 番目の実験では, 生命が存在するかもしれない反応が検出された (Levin and Straat 1977)．しかし, 有機物が検出限界以下であったため, 火星表面には生命は存在しないと結論された．2000 年代に入って, バイキングの有機物分析装置の再検討が進んだ．バイキングの有機物分析装
置は, 1g 土壌あたり 106 〜107 細胞の検出感度しか無い事が明らかとなった (Glavin, et al.2001; Navarro-Gonzalez, 2006)．
これは地球上であっても, 深海底, アタカマ砂漠, 南極砂漠等の微生物濃度が極めて低い場所 (1g 土壌あたり 104 細胞) では, 生命を検出できない感度である．
MSL: Curiosity が Gale crater で検出した有機物は, 火星由来かどうかは分からないが, 検出された CH3Cl の量は 1g 土
壌あたり 4 μ g であった (Ming et al.,2014)．これを総有機炭素量で有ると考え, アタカマ砂漠で検出された総有機炭素量と土壌中微生物量との比率 (Connon et al．2007) を考えると, 1g 土壌あたり 4 × 104 細胞の微生物がいる事になる．本計
画では最も水の存在の確実視される場所をターゲットとしている．ゲールクレータで検出された CH3Cl が細胞由来であれば, 確実に検出できる感度で探査を行う．
生命が発見された場合, 火星生命を対象として分析が行われ, 新 (真) 生物学が誕生する．
第二段階の生命探査では遺伝物質 DNA とアミノ酸の分析を行う。もし、火星生命が DNA を持たないあるいは、持っていても AGCT を用いていないことがわかれば、地球とは独立した生命であることがわかる。同じ DNA(AGCT) を用いていることが明らかとなった場合には、第三段階の生命探査では遺伝子の系統解析を行う。遺伝子を調べて地球生物との類似性が無ければ、独立に誕生した DNA 生物であることがわかる。類似性がある場合には、系統関係をしらべ、地球だけで生命が誕生し地球から火星へ移動したのか, 逆に火星だけで生命が誕生し火星から地球に生命が移動した可能性があるのかを系統解析で判別することが可能である
仮に火星に生命が検出されなかった場合, 生命誕生に多くの課題を与える．A．もし火星と地球の双方で生命が誕生したのであれば, 地球でのみ生命を存続させた条件は何なのか．B．生命が地球でだけ誕生したのであれば, 火星で生命が誕生し得なかった決定的条件は何なのか．C．火星でのみ生命が誕生したので有れば, 火星で生命が絶滅した理由はなにか．D．地球と火星以外から生命が飛来したのであれば, 火星で生命が定着しえなった要因は何なのか．いずれの場合にも, 生命誕生モデルの大幅な再検討が必要になる． 火星で生命が誕生しなかったにせよ, 地球から生命が移動する可能性が十分あることを考えるならば, 火星に移動した生命は今日までに絶滅したことになる．火星にはどのような条件が生命存続に欠けていたのか．
火星に置ける前生命環境探査は惑星科学会の工程表の中に含まれ, 生命探査はアストロバイオロジーネットワークと宇宙生物学会の工程表に位置づけられている．
参考文献
1．Levin G. V. and Straat., P. A. 1977, J. Geophys. Res., 82, 4663-4667.
2．Glavin, D. P. et al. 2001, Earth Planet Sci. Lett. 185, 1-5.
3．Nabarro-Gonzalez, R. et al. 2006, Proc. Natl. Acad. Sci. 103, 16089- 16094.
4．Ming, D. W. et al. 2014, Science, 343, DOI:10.1126/science.1245267
5．Connon, S. A et al. 2007, J. Geophys. Res. 112, G04S17, doi:10.1029/ 2006JG000311

キーワード: 蛍光顕微鏡, 蛍光色素, 生命の起源, 進化系統樹
Keywords: Fluorescence microscope, Fluorescence pigment, Origin of life, Phylogenetic tree

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PPS05-07

会場:A03

時間:5 月 28 日 10:00-10:15

Life-Detection Microscope (LDM) onboard 2020 Mars Mission MELOS
Life-Detection Microscope (LDM) onboard 2020 Mars Mission MELOS
佐藤 毅彦 1∗ ; 山岸 明彦 2 ; 宮川 厚夫 2 ; 佐々木 聰 3 ; 藤田 和央 1 ; LDM Team1
SATOH, Takehiko1∗ ; YAMAGISHI, Akihiko2 ; MIYAKAWA, Atsuo2 ; SASAKI, Satoshi3 ; FUJITA, Kazuhisa1 ;LDM, Team1
1
1

JAXA, 2 Tokyo University of Pharmacy and Life Science, 3 Tokyo University of Technology
JAXA, 2 Tokyo University of Pharmacy and Life Science, 3 Tokyo University of Technology

Life-Detection Microscope (LDM) is the primary science payload onboard the MELOS rover which we propose to launch in2020. LDM is designed to achieve a sensitivity (104 cells per gram soil) which is two orders of magnitude better than the Viking
Lander experiments. The strategy to achieve this high sensitivity includes: 1) cells, if exist, are dyed with SYTO24, PI, andCDMA pigments; 2) the fluorescence from dyed cells (excited with blue light at 488 nm) is imaged with 1 um/pixel resolution;3) the field of view in one image is 1 mm2 ; and 4) 2 mm3 volume of Martian soil is scanned.
LDM consists of 3 components: Sample-Handling System (SHS), Fluorescence Microscope (FluM), and Driver and Data
Processor (DDP). To receive soil sample from the robotic arm of the rover, one ”empty” sample container is selected and is
moved to the sample inlet position (X and Y movements in SHS). After receiving the soil sample, the dye is injected and then thecontainer lid is closed so that the rapid evapolation of the solvent under the atmospheric pressure (6 hPa) of Mars is avoided. A
set of regolith and dust images in white light are acquired before ”fluorescence” mode is started. In ”fluorescence” mode, a set ofimages with different focal depths (0 to 0.1 mm) are acquired at each of 20 (X, Y) positions, achieving scan of desired volume (2mm3 ) of soil sample. The images are examined for suspicious objects and small sections of images which include such objects,
if any, are stored in the rover’s data recorder for later downlink to the earth.
We will report progress in development of LDM and will discuss the operation strategy of LDM in the mission period on Mars.
キーワード: Mars, Life, Microscope, Fluorescence, Soil, Rover
Keywords: Mars, Life, Microscope, Fluorescence, Soil, Rover

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PPS05-08

会場:A03

時間:5 月 28 日 10:15-10:30

Exploration of carbonate and clay mineral on Mars: clues for climate, atmosphere, anddeep hydrosphere of early Mars
Exploration of carbonate and clay mineral on Mars: clues for climate, atmosphere, anddeep hydrosphere of early Mars
関根 康人 1∗ ; 臼井 寛裕 2 ; 渋谷 岳造 3 ; 門屋 辰太郎 1 ; 長 勇一郎 4 ; 亀田 真吾 4 ; 橘 省吾 5 ;渡邊 誠一郎 6
SEKINE, Yasuhito1∗ ; USUI, Tomohiro2 ; SHIBUYA, Takazo3 ; KADOYA, Shintaro1 ; CHO, Yuichiro4 ;KAMEDA, Shingo4 ; TACHIBANA, Shogo5 ; WATANABE, Sei-ichiro6
1

東京大学, 2 東京工業大学, 3 海洋研究開発機構, 4 立教大学, 5 北海道大学, 6 名古屋大学
University of Tokyo, 2 Tokyo Institute of Technology, 3 JAMSTEC, 4 Rikkyo University, 5 Hokkaido University, 6 Nagoya University

1

High-resolution remote sensing data of Mars Noachian terrains show the widespread existences of clay minerals formed bygroundwater circulations [1]. This suggests that hydrothermal activity in deep crusts may have played a major role in hydrological cycles on early Mars [1], which is contrast to those on current Earth and might be similar to those occurred on Europa or
Enceladus [2, 3]. To date, however, Mars rovers have performed analyses at outcrops of sedimentary rocks formed mainly by
open water activity [4, 5]. Lack of knowledge on the nature of groundwater activity obscures us to understand a whole picture ofhydrological cycles, aqueous geochemistry, and habitability on early Mars.
Recent observations and models suggest that there are some locations where groundwater upwelled on the surface of earlyMars [6]. These include one of the deepest craters on Mars, McLaughlin Crater, which exhibits layered deposits of carbonatesand Mg-Fe-bearing phyllosilicates on the crater floor [6]. The proposed mineral assemblages suggest the occurrence of geochemistry between CO2-bearing, alkaline groundwater and ultramafic rocks [6]. This implies that the outcrops of McLaughlin
Crater could serve as a unique window to look into the nature of groundwater activity and its interactions with the atmosphere ofearly Mars.
Here we propose a Mars rover mission to perform geological and geochemical analyses of outcropped carbonates and clay
minerals on McLaughlin Crater. Geological observations of the outcrops would determine the formation processes of these layered deposits. The aqueous geochemical conditions (e.g., the composition, redox state, and pH of groundwater, water-rock ratio,
and temperature) would be determined based on results of detailed chemical and mineralogical compositions of the outcrops.
These observational data enable us to constrain redox potentials of groundwater, which could support deep biosphere on Mars.
In addition, we can estimate the partial pressure of atmospheric CO2 equilibrated with the groundwater. This, in turn, meansthat our mission will be able to answer the long-standing question whether early Mars had a dense CO2 atmosphere, which will
provide critical insights into the habitable zone [7] and formation process of terrestrial planets in the solar system and beyond.
[1] Ehlmann et al., 2011, Nature, 479, 53. [2] Hsu et al., 2015, Nature, in press. [3] Zolotov and Kargel, 2009, in Europa, Univ.
Arizona Press. [4] Squyres et al., 2004, Science, 306, 1709. [5] Vaniman et al., 2014, Science, 343, 1243480. [6] Michalski etal., Nature Geosci., 6, 133. [7] Kasting et al., 1993, Icarus, 101, 108.

キーワード: 火星, 探査, 地球化学, 炭酸塩, 熱水活動, 大気
Keywords: Mars, exploration, geochemistry, carbonate, hydrothermal activity, atmosphere

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PPS05-09

会場:A03

時間:5 月 28 日 10:30-10:45

MEMS pirani pressure sensor for the Mars Organic Molecule Analyzer ( MOMA) of the
ExoMars Mission
MEMS pirani pressure sensor for the Mars Organic Molecule Analyzer ( MOMA) of the
ExoMars Mission
ADACHI, Tomoko1∗ ; SOUTHARD, Adrian2 ; BROWN, Gary3 ; JOHNSON, Christopher3 ; GONNSEN, Zach4 ;RIEMANN, Lisa5 ; AREVALO, Ricardo3 ; PINNICK, Veronica3 ; DANELL, Ryan3 ; BRINCKERHOFF, William3 ;MAHAFFY, Paul3ADACHI, Tomoko1∗ ; SOUTHARD, Adrian2 ; BROWN, Gary3 ; JOHNSON, Christopher3 ; GONNSEN, Zach4 ;RIEMANN, Lisa5 ; AREVALO, Ricardo3 ; PINNICK, Veronica3 ; DANELL, Ryan3 ; BRINCKERHOFF, William3 ;MAHAFFY, Paul3
1

Dept. of Physics, Catholic University of America, Washington, DC, 2 University Space Reserch Association, Columbia, MD,
NASA Goddard Space Flight Center, Greenbelt, MD, 4 MICROTELL LLC., Winterville, NC, 5 AS and D Inc., Greenbelt, MD
1
Dept. of Physics, Catholic University of America, Washington, DC, 2 University Space Reserch Association, Columbia, MD,
3
NASA Goddard Space Flight Center, Greenbelt, MD, 4 MICROTELL LLC., Winterville, NC, 5 AS and D Inc., Greenbelt, MD
3

The Mars Organic Molecule Analyzer, MOMA is a collaborative mission by European Space Agency, and NASA Goddard
Space Flight Center. MOMA is a key analytical instrument aboard the ExoMars rover, set to launch in 2018. The rover will
search for past and present evidence of martian life The twin rovers Spirit and Opportunity have confirmed that water was longstanding on the surface of Mars long ago. The Curiosity rover found aromatic, organic compounds in the mudstone at the bottomof a possible ancient lake. Mars Science Laboratory scientists found that chlorobenzene was formed during the reactions inside
the Sample Analysis (SAM) instrument from martian chlorine and carbon during the heating of perchlorates known to be present
in martian soil. The ExoMars rover will sample martian soil/rock at depths of up to 2 meters, deeper than any instrument before
it. The rover collect the sample and analyze them by MOMA. The MOMA has two operation modes: Gas Chromatograph-Mass
Spectrometry (GC-MS); and Laser Desorption-Mass Spectrometry (LD-MS). (Please see the image) LD-MS employ laser desorption ionization to avoid the need to heat the sample, thereby preventing perchlorate reactions, which complicate identificationof compounds in the sample. GC-MS will identify the chirality of organic molecules, improving understanding of how thesemolecules were formed.
The MEMS (microelectro-mechanical system) pirani pressure sensor is a critical component that will be used to ensure the ion
trap mass spectrometer0s time sensitive operation in the LD-MS mode. It employ a high voltage for ionizations, and knowing
the pressure of the MS chamber by miliseconds time scale is critical. The pressure data is used for the telemetry of the MS
operation. Also the pirani pressure sensor has a critical function that pressure changes as a discontinuous inlet and pump work
together to sample the Mars atmosphere in LD-MS mode. It also has to work at ambient temperatures varying from -20 to 80
degrees Celsius and be calibrated for both carbon dioxide for sampling martian atmosphere and helium during use of the gas
chromatograph. The MEMS pirani sensor provides better than 0.1 mtorr accuracy over the critical pressure range from 1 mtorr
to 0.1 mtorr and has a usable pressure range from 0.1 mtorr to 0.1 torr. This paper will focus on the characterization of the pirani
sensor and its electrical interface and modeling ideas of a next generation of MEMS pressure sensor for future planetary andspace missions.
キーワード: Robotic Rover Mission on Mars, MEMS pirani pressure sensor, Organic molecule analysis, Ion Trap, Laser Desorption Mass Spectroscopy, Gas Chromatograph Mass Spectroscopy
Keywords: Robotic Rover Mission on Mars, MEMS pirani pressure sensor, Organic molecule analysis, Ion Trap, Laser Desorption Mass Spectroscopy, Gas Chromatograph Mass Spectroscopy

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時間:5 月 28 日 10:30-10:45

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PPS05-10

会場:A03

時間:5 月 28 日 11:00-11:15

火星着陸探査機におけるその場 K-Ar 年代測定に向けた着陸地点検討
Possible landing sites on Mars for an in-situ K-Ar dating by future Japan’s Mars rover
mission
三浦 弥生 1∗ ; 長 勇一郎 2 ; 諸田 智克 3 ; 宮本 英昭 4 ; 臼井 寛裕 5 ; 亀田 真吾 2 ; 杉田 精司 6 ;岡崎 隆司 7
MIURA, Yayoi N.1∗ ; CHO, Yuichiro2 ; MOROTA, Tomokatsu3 ; MIYAMOTO, Hideaki4 ; USUI, Tomohiro5 ;KAMEDA, Shingo2 ; SUGITA, Seiji6 ; OKAZAKI, Ryuji71

東京大学地震研究所, 2 立教大学, 3 名古屋大学, 4 東京大学博物館, 5 東京工業大学, 6 東京大学大学院理学系研究科, 7 九
州大学
1ERI, Univ. Tokyo, 2 Rikkyo Univ., 3 Nagoya Univ., 4 Univ. Museum, Univ. Tokyo, 5 Tokyo Inst. Tech., 6 Univ. Tokyo, 7 Kyushu
Univ.

Mars shows a variety of surface features affected by geologic processes. Though the crater-based dating has estimated surface
ages, ranging from nearly 4.5 Ga age to recent, the absolute ages have not been determined for Martian samples except a mudstone at Gale crater by the Curiosity rover mission (4.21 ± 0.35 b.y.) and meteorites that come from somewhere on Mars. The
authors have been developing an in-situ K-Ar dating system for future Japan’s landing mission on Mars (e.g., Cho et al., 2014,2015). In this paper, aims of the chronologic investigation using the system onboard a Mars rover/lander and appropriate landingsites are discussed.
Studies of impact crater densities present three representative eras for geologic history of Mars; Noachian, Hesperian andAmazonian (e.g., Tanaka, 1986). Abundant water should have existed early in Martian history (likely the Noachian and a part of
the Hesperian), but most of them disappeared. In order to understand habitable environment, climate changes and atmosphere
evolution of Mars it is important to determine the absolute ages of geologically-well-defined Noachian/Hesperian samples. Considering crater chronology, mineralogy, geological setting and engineering requirements (altitude, latitude and thermal inertia),
we propose three regions that are covered by Hesperian volcanic rocks as candidates of chronologic investigation; Syrtis Major
Planum, north-east side of Tharsis and peripheral area of Amazonis Planitia. Crater counting based on CTX and HRSC images
applied to five specific areas in Syrtis Major provides ages ranging in 3.0 - 3.6 Ga (where the model by Hartmann and Neukum,2001 is adopted). Among which, two areas reveal resurfacing evidences; the crater frequency gives older ages of 3.7 - 3.8 Ga
for the sizes >1 km in diameter and the thickness of the younger lava (for the sizes <1 km) is estimated to be ~ 40 m. Syrtis
Major, having gentle slope and less abundant dust, is a highly recommended region for the landing site. Further information suchas local morphology and shock and alteration phenomena should also be considered.
キーワード: 火星, 火星探査, K-Ar 年代, 年代学, ヘスペリアン, Syrtis Major
Keywords: Mars, Mars exploration, K-Ar dating, chronology, Hesperian, Syrtis Major

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PPS05-11

会場:A03

時間:5 月 28 日 11:15-11:30

火星ローバ搭載電磁波・音波観測による火星地表面現象の遠隔観測
Remote sensing of Martian surface events by Electro-magnetic and Sonic Wave observation aboard a Martian rover
山本 真行 1∗ ; 佐藤 光輝 2 ; 石坂 圭吾 3 ; 高橋 幸弘 2 ; 鴨川 仁 4 ; 小郷原 一智 5 ; 宮本 英昭 6
YAMAMOTO, Masa-yuki1∗ ; SATO, Mitsuteru2 ; ISHISAKA, Keigo3 ; TAKAHASHI, Yukihiro2 ;KAMOGAWA, Masashi4 ; OGOHARA, Kazunori5 ; MIYAMOTO, Hideaki61

高知工科大学, 2 北海道大学, 3 富山県立大学, 4 東京学芸大学, 5 滋賀県立大学, 6 東京大学博物館
Kochi University of Technology, 2 Hokkaido University, 3 Toyama Prefectural University, 4 Tokyo Gakugei University, 5 Universityof Shiga Prefecture, 6 The Unversity of Tokyo

1

In order to detect many kinds of surface events on Mars, a small instrument with electro-magnetic and sonic wave receivers
has been considered as one of the remote sensing equipments onboard a future Japanese Mars rover.
By combining the observation of 3-axes electro-magnetic waves and sonic waves, precise identification of the events source
coordinates with respect to the rover position can be realized because of the phase difference of each detecting waves and large
difference of the speed of light (c) and sound (Cs). The observation plan has been discussed as a remote sensing instrument for
distribution measurement of Martian discharge events (like lightning and thunder on the Earth), however, it can also be applied
for the Martian surface studies as a very unique equipment, moreover, the size, weight, and power resources for the instrument issmall and suited for installing on the small rover system planned to land the Mars.
On the Mars, as a result of the most recent research activities mainly by the NASA MSL (Opportunity) rover and several
orbiters, many possible surface events like fluid motion on the edge of craters, so called RSL (Recurring Slope Lineae) seen asa narrow dark-tones streak activities depending on the Martian season change. Moreover, some scientists reported the possible
regions of gas eruption from the surface of the Mars.
Here, we will introduce the recent progress of the instrumentation design and environment test results of the electro-magnetic
and sonic wave observation instruments for the future exploration by landing explorer on the Mars.
キーワード: 火星, 電磁波, 音波, 地表面現象, ローバ, 遠隔観測
Keywords: Mars, Electro-magnetic wave, Sonic wave, Surface events, Rover, Remote sensing

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PPS05-12

会場:A03

時間:5 月 28 日 11:30-11:45

Characterization of Martian Regolith: Toward 2020s Mars Exploration Missions
Characterization of Martian Regolith: Toward 2020s Mars Exploration Missions
臼井 寛裕 1∗ ; Yamagishi Akihiko2 ; Sato Takehiko3 ; Miyamoto Hideaki4 ; Kameda Shingo5 ;Fujita Kazuhisa3 ; Sekine Yasuhito4 ; Tachibana Shogo6 ; Watanabe Sei-ichro7
USUI, Tomohiro1∗ ; YAMAGISHI, Akihiko2 ; SATO, Takehiko3 ; MIYAMOTO, Hideaki4 ; KAMEDA, Shingo5 ;FUJITA, Kazuhisa3 ; SEKINE, Yasuhito4 ; TACHIBANA, Shogo6 ; WATANABE, Sei-ichro7
1

Tokyo Institute of Technology, 2 Tokyo University of Pharmacy and Life Science, 3 ISAS, JAXA, 4 The University of Tokyo,
Rikkyo University, 6 Hokkaido University, 7 Nagoya University
1
Tokyo Institute of Technology, 2 Tokyo University of Pharmacy and Life Science, 3 ISAS, JAXA, 4 The University of Tokyo,
5
Rikkyo University, 6 Hokkaido University, 7 Nagoya University
5

Mars once had surficial liquid water (paleo-ocean/lake) and shows a promising sign of current subsurface water/ice. The
existence of hydrosphere and cryosphere makes Mars the unique accessible habitable planet next to the Earth. The water-rockinteraction between the lithosphere and hydrosphere/cryosphere through the history of Mars has produced a variety of surface
rocks (regolith) containing sheet-silicates, phosphates, sulfates, and carbonates, which are closely linked to climate and thepotential for life on Mars. This study characterizes the physico-chemical properties (chemical composition, mineral abundance,
reflectance feature, and geometric distribution) of Martian regoliths. We further present a way to leverage the database on Martian
regoliths as a tool for interpreting remote sensing analyses by onboard instruments (e.g. Life Detection Microscope) for Mars
exploration missions in 2020s.
キーワード: Mars, regolith
Keywords: Mars, regolith

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PPS05-13

会場:A03

時間:5 月 28 日 11:45-12:00

MELOS 着陸候補地点の地質学的考察
Geological implications of landing-site candidates of the MELOS mission
宮本 英昭 1∗ ; 小松 吾郎 2 ; 臼井 寛裕 3 ; Dohm James1 ; 逸見 良道 1 ; 新原 隆史 1 ; 徐 路媛 1 ;亀田 真吾 5 ; 佐藤 毅彦 6 ; 山岸 明彦 4
MIYAMOTO, Hideaki1∗ ; KOMATSU, Goro2 ; USUI, Tomohiro3 ; DOHM, James1 ; HEMMI, Ryodo1 ;NIIHARA, Takafumi1 ; LUYUAN, Xu1 ; KAMEDA, Shingo5 ; SATOH, Takehiko6 ; YAMAGISHI, Akihiko4
1
1

東京大学, 2 IRSPS, 3 東京工業大学, 4 立教大学, 5 宇宙科学研究所, 6 東京薬科大学
University of Tokyo, 2 IRSPS, 3 TiTech, 4 Rikkyo University, 5 ISAS/JAXA, 6 TUPLS

Ancient Mars is now considered to have had environment somewhat similar to that of Earth in terms of the existence of large
bodies of water, a wide range of surface oxidation states, appearances of variety of chemical components potentially building
blocks of life, and a magnetic field. Endogenic activities have continued even until very recently, and recent water-related geological features indicate prolonged existence of an aquifer system, where a habitable environment may exist for a significant
period of time. Occasional releases of volatiles from such an aquifer system may ultimately account for the inconclusive result(not unambiguous denial) of metabolism-detection instrument onboard Viking landers. Japanese MELOS Mars mission is proposed to carry an in-situ life detection package onboard a 150kg-sized rover, as well as a visible-near IR camera and a Ground
Penetrating Radar system to perform geological investigation.
Because the primary purpose of the MELOS mission is to perform the Life Detection Microscope (LDM) instrument experiment, which is designed to detect less than 10ˆ4 cells in 1 gram clay, orders of magnitude higher than previous attempts performed
by Viking landers, landing-site candidates of the MELOS mission are selected in terms of the possibility of the existence of nearsurface water and recent geological and hydrological activities including the possible release of volatiles (specifically, relatively
high water activity (Aw>0.6), a relatively higher maximum environmental temperature (T>250), and an existence of gradientsof free energy). We propose Melas chasma as a prime candidate because of the existence of recurring slope lineae (RSL), wheretraces of possible liquid water and seasonal flow have been reported, as well as the fact that Valles Marineris provides the best
exposures of the ancient geologic history of Mars. The latter includes: (1) Melas chasma being the widest and deepest partof the Valles Marineris; (2) it being connected to the outflow channels; (3) Interior Layered Deposits (ILDs) showing various
sulfates deposits, suggesting the existence of abundant past water; and (4) various phyllosillicates having been detected among
the canyon units. As for the current volatile release, we find Tharsis/Elysium Corridor region is the best candidate, which shows
evidence of long-lived water enrichment and recent geologic activity, including recent venting that could bring materials fromthe subsurface to the surface environment. In this talk, we examine the morphologic characteristics of these features and discussgeological context of the candidate landing sites.

キーワード: 火星, MELOS 計画, 生命探査, 水, 活動度
Keywords: Mars, MELOS, life detection, water, current activity

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PPS05-14

会場:A03

時間:5 月 28 日 12:00-12:15

火星着陸探査の気象測器
Meteorological Instruments of Mars EDL
乙部 直人 1∗ ; はしもと じょーじ 2 ; 千秋 博紀 3 ; 仲吉 信人 4 ; 栗原 純一 5
OTOBE, Naohito1∗ ; HASHIMOTO, George2 ; SENSHU, Hiroki3 ; NAKAYOSHI, Makoto4 ; KURIHARA, Junichi5
1

福岡大学理学部, 2 岡山大学大学院自然科学研究科, 3 千葉工業大学惑星探査研究センター, 4 東京理科大学理工学部, 5 北海道大学 大学院理学研究院
1
Fukuoka Univ, Faculty of Science, 2 Department of Earth Sciences, Okayama University, 3 Planetary Exploration ResearchCenter, Chiba Institute of Technology, 4 Tokyo University of Science, Fuculty of science and technology, 5 Graduate School of
Science, Hokkaido University

Mars Exploration plan is started for Landing at 2020.
Landing to Mars surface, Moving with Rover, and Searching Life itself.
We, Melos Meteorological Sub Working group, also proposal some instruments.
Those are including Thermometer, Anemometer, Barometer, Radiation Meter, Radiation Thermometer and Navigation camera,
LIDAR, Particle counter.
We call first 5 instruments basic instruments set, and last 3 instruments Dust sensors.
This presentation is to introduce developing and testing sate of progress of these sensors.
[Thermometer] We use 3 different color thermos-sensors. Difference of radiative absorption makes difference temperature of
sensor. Sensible heat is calculated it’s difference. And 1 thermo-sensor is heated, for calculating wind velocity.
[Barometer] This instruments is in TRL-5. Using Impedance of Cristal
Oscillator is changing with friction of atmosphere.
If we know the air components, the friction is a function of Pressure, so it works as a barometer.
[Radiation Thermometer] Thermocouple seeing to the surface of Mars. It can measure Surface temperature.
[Anemometer] Same as Thermometer. But we use 4 couple of sensor, for calculating wind direction.
[Navigation Camera] This is a BUS-equipment to monitor around the rover. We use this camera to detect dust-devils.
[LIDAR] Counting the back scatter of LASER, We obtain a sum of cross-section of dusts along LASER path. Resolution
along path is around 1m.
[Particle Counter] Small In-situ sensor, mechanism is similar to LIDAR.
Counting the scatter of light within very small (0.5x2x1mm) region.
This can measure number of particle for separated to 5 bin of size.
State of developing is very different each other, some is only discussion,
The others are tested with Mars like environment, Mars Environment Simulation Chamber settled in PERC/Chiba Institute ofTechnology).

キーワード: 火星, 気象
Keywords: Mars, Meteology

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PPS05-15

会場:A03

時間:5 月 28 日 12:15-12:30

火星探査のための表層環境評価: 雲解像モデル CReSS の火星大気への適用
Assessment of Mars surface environment for a exploration program: application of CReSS
to Martian atmosphere
杉山 耕一朗 1∗ ; 小高 正嗣 2 ; 中島 健介 3 ; 高橋 芳幸 4 ; 乙部 直人 5 ; 西澤 誠也 6 ; 林 祥介 4 ;はしもと じょーじ 7 ; 長谷川 晃一 8 ; 榊原 篤志 8 ; 坪木 和久 9
SUGIYAMA, Ko-ichiro1∗ ; ODAKA, Masatsugu2 ; NAKAJIMA, Kensuke3 ; TAKAHASHI, Yoshiyuki O.4 ;OTOBE, Naohito5 ; NISHIZAWA, Seiya6 ; HAYASHI, Yoshi-yuki4 ; HASHIMOTO, George7 ; HASEGAWA, Kouichi8 ;SAKAKIBARA, Atsusi8 ; TSUBOKI, Kazuhisa91

宇宙航空研究開発機構 宇宙科学研究所, 2 北海道大学, 3 九州大学, 4 神戸大学, 5 福岡大学, 6 理化学研究所 計算科学研究推進機構, 7 岡山大学, 8 中電シーティーアイ, 9 名古屋大学
1
ISAS/JAXA, 2 Hokkaido University, 3 Kyushu University, 4 Kobe University, 5 Fukuoka University, 6 RIKEN Advanced Institutefor Computational Science, 7 Okayama University, 8 chuden CTI, 9 Nagoya University
日本の宇宙惑星コミュニティにおいて計画中の火星探査計画では, 着陸機の設計および運用計画立案のために, 着陸候
補地点の表層環境評価が必要とされている. 我々は表層環境評価を実施するための環境整備の一環として, 雲解像モデル
CReSS (Tsuboki and Sakakibara, 2002) の火星大気への適用を進めている.

CReSS は準圧縮方程式系 (Klemp and Wilhelmson, 1978) に基づいた数値モデルである. 火星大気に適用するために, 惑
星大気大循環モデル DCPAM (Takahashi et al. 2012) で使われている 火星用の放射計算コード (Takahashi et al., 2006) を導入した. 地形, アルベド, 熱慣性の値としては Mars Global Surveyor の観測データを用いる. CReSS に含まれている地球用の暦は火星の自転および公転周期にあわせて変更した.
モデルの動作検証として, 地形と大規模循環の効果を考慮しない理想化実験を多数実施した. まず始めに, 同じ放射計算
コードを用いる鉛直 1 次元の放射対流計算 (DCPAM-1D) と設定を揃えた比較実験を行い, 地表面温度の日変化と地表面熱収支が両計算で概ね一致することを確認した. 次に, NASA の火星探査ローバー Spirit と Opprtunity の観測地点の日射量条件を与えた数値実験を行った. Spiga et al. (2010) と同様に乱流過程における混合長の定式として Deardorff (1980) を用いることで, 火星探査ローバーの観測した日中の鉛直温度プロファイルと整合的な計算結果が得られることを確認した.
これらの理想化実験を踏まえ, 我々は着陸候補地点を想定したより現実的な数値実験を実施している. この実験においては地形と大規模循環の効果を考慮する. 大規模循環の効果は初期値および境界値として DCPAM によってシミュレートされた火星全球気象データを導入することで考慮する.
本発表では, 数値モデルの概要を示すと共に, これまで行った数値実験の結果を紹介する.
キーワード: 火星大気, 惑星探査, 数値計算, 雲解像モデル
Keywords: Martian atmosphere, planetary exploration, numerical modeling, cloud resolution model

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PPS05-16

会場:A03

時間:5 月 28 日 12:30-12:45

Scientific significance of sample return from Martian moons
Scientific significance of sample return from Martian moons
橘 省吾 1∗ ; 渡邊 誠一郎 2 ; 関根 康人 3 ; 臼井 寛裕 4
TACHIBANA, Shogo1∗ ; WATANABE, Sei-ichiro2 ; SEKINE, Yasuhito3 ; USUI, Tomohiro41

北海道大学大学院理学研究院自然史科学部門, 2 名古屋大学大学院環境学研究科地球環境科学専攻, 3 東京大学大学院理学系研究科地球惑星科学専攻, 4 東京工業大学理工学研究科地球惑星科学専攻
1
Dept. Natural History Sciences, Hokkaido University, 2 Division of Earth and Planetary Sciences, Nagoya University, 3 Dept.
Earth and Planetary Science, The University of Tokyo, 4 Dept. Earth and Planetary Sciences,Tokyo Institute of Technology

The asteroid explorer Hayabusa2 began a six-year round trip in December 2014 to return surface samples of a near-Earthcarbonaceous-type asteroid 1999 JU3 following Hayabusa’s successful return of the first asteroid samples to Earth. Hayabusa2
will arrive at 1999 JU3 in mid-2018, and fully investigate and sample the asteroid at three locations during its 18-month stay.
The samples from 1999 JU3 will be delivered to the Earth in December 2020. Primitive small bodies are the evolved remnantsof planetesimals that were the building blocks of planets, and detailed on-site observation by a spacecraft and analyses of returnsamples will provide direct evidence of planetesimal formation and dynamical and chemical evolution of the solar system.
Moreover, such small bodies could have delivered volatile components to rocky planets in the early solar system.
Sample return missions to primitive small bodies such as main belt asteroids, Jovian Trojan asteroids, icy satellites, and comets
require a timescale of decades, and it is important to plan short-term exploration missions to primitive bodies. Here we proposea sample return mission to Martian moons (Phobos and Deimos), of which characteristics resemble those of C-type or D-type
asteroids. If they are captured main-belt asteroids, their surfaces have not been heated as much as near-Earth asteroids are.
Martian moons are thus likely to preserve more primitive materials such as ice, which is one of possible constituents responsible
for their low bulk-densities. If they are remnants of building blocks of Mars, the returned samples will provide us the first anddirect information on the formation of Mars, the bulk chemistry of Mars, and the isotopic compositions of volatile elements as
a starting point of Martian environmental evolution. Isotopic compositions of returned samples will be a key to address thisissue on the origin of Martian moons. Surface regolith of Martian moons may contain ejecta from the Martian surface and/or
the escaped Martian atmosphere, and the returned samples may enable us to put constraints on the crustal and environmental
evolution of Mars. The remote-sensing observation of Martian atmosphere and surface from the spacecraft can also be done
from the spacecraft. In this presentation, we will describe the outline and scientific rationales of the sample return mission from
Martian moons.
キーワード: 火星, 衛星, フォボス, ダイモス, サンプルリターン
Keywords: Mars, Satelite, Phobos, Deimos, Sample return

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