火星の大気中のメタンの背景レベルは,強い季節的変動を示しています
Christopher R Webster1, Paul R Mahaffy2, Sushil K Atreya3
1NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. chris.r.webster@jpl.nasa.gov.
まとめ
火星でのメタンは ランダムな変動ではなく 繰り返される季節的な変化を示しています キュリオシティ・ローバーのデータによると 地表や地下の場所が これらの大気変動の 原因であると考えられます
科学分野:
- 惑星科学
- 天体生物学
- 大気科学
背景:
- 火星の大気中のメタンのレベルは変動し,理解は薄い.
- 過去の測定は 時間と場所において 繰り返しできないため 説明が困難でした
研究 の 目的:
- 火星の大気中のメタンの源と変動性を調査する.
- 再現可能なパターンを in situ 測定で分析する.
主な方法:
- Curiosityローバーの調整可能なレーザースペクトロメーターを in situ 測定に使用した.
- ゲイルクレーター内の 5 年間のデータを収集した.
主要な成果:
- 背景メタン濃度の季節的変動が確認された (体積で10億分の0.24~0.65).
- 背景メタンの平均濃度は0.41±0.16ppbvであった.
- 偶発的なメタンピークが 7ppbvまで検出されました
結論:
- 観測された季節的なメタンの変動は,既知の表面プロセスからの予測を超えています.
- 結果は,火星の表面または地下貯蔵庫からの局所的なメタン放出と一致しています.
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