火星の大気. 火星の大気. 火星のメタン検出とゲールクレーターでの変動性

Christopher R Webster¹, Paul R Mahaffy², Sushil K Atreya³

¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov.

Science (New York, N.Y.)

|December 18, 2014

まとめ

火星は背景メタンのレベルが低いが,エピソード的な高メタンのピークは,未知の源を示唆する. 好奇心とは,好奇心です.

科学分野:

惑星科学は惑星科学である.
天体生物学アストロバイオロジー
大気化学大気化学

背景:

火星でメタンの羽根が観測されているが,説明は欠けている.
以前のモデルは,塵や隕石からのメタンを示唆していたが,これらは不十分である.
火星のメタンの理解は,潜在的居住性を評価するための鍵です.

研究の目的:

In situデータを用いて火星の大気中のメタン濃度を測定する.
火星で観測されたメタンの変動の源を調査する.
測定結果を既存の地化学および大気モデルと比較する.

主な方法:

試料分析マース (SAM) 機器セットのチューナブルレーザースペクトロメーター (TLS) を利用しました.
ゲールクレーターで20ヶ月の間,現地測定を行った.
背景メタンの濃度およびエピソード性高濃度に関するデータを分析した.

主要な成果:

背景メタンの平均レベルが0.69 ±0.25 ppbv.と検出されました.
観測されたエピソード的なメタンピークは,60日間で7.2 ± 2.1 ppbvまで上昇した.
背景レベルは,紫外線劣化モデルによって予測されるよりも低い.

結論:

火星は,以前モデル化されたものよりも背景メタンが著しく低いことを示しています.
偶発的なメタンの放出は,火星上の未知のメタン源が活発であることを示している.
この偶発的なメタンの起源を特定するためにさらなる研究が必要です.

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