まとめ
バイキング1号ミッションは,火星の上層大気は主に二酸化炭素 (CO2) であり,わずかな量の窒素 (N2),アルゴン (Ar),酸素 (O2) も含まれていることを明らかにした. このCO2の優位性は,火星の下層大気にも広がっており,降下データによって確認されています.
科学分野:
- 惑星科学 惑星科学
- 大気科学 大気科学
- 天体生物学 アストロバイオロジー
背景:
- 惑星の大気の組成を理解することは,居住可能性と大気の進化を評価するために不可欠です.
- 火星の大気組成に関する以前の知識は限られており,インシトゥ測定が必要でした.
研究 の 目的:
- バイキング1ミッションからのデータを用いて火星の大気の組成と温度を決定する.
- 大気成分と混合比の垂直分布を分析する.
主な方法:
- バイキング1機内の中性質量スペクトロメーターと減速電位分析器を利用した.
- 火星表面への降下時の大気圧と気温データを分析した.
主要な成果:
- 火星の上層大気の主要な成分として二酸化炭素 (CO2) を特定した.
- 窒素 (N2),アルゴン (Ar),酸素 (O2),一酸化炭素 (CO) の微量測定は,標高約135kmで行われた.
- 140~200 km の間の平均大気温を 180 ± 20 K と決定しました.
- 記録された大気圧は7.3ミリバーで,空気の気温は241K. バイキング1の着陸地点.
- 観測された分子酸素イオン (O2+) は,火星のイオノスフィアの重要な成分である.
結論:
- 火星の大気は主に二酸化炭素 (CO2) で,上層から地表まで広がっています.
- このデータは,二酸化炭素が火星の下層大気の主要な構成要素であるという仮説を裏付けている.
- バイキング1号の測定は,火星の大気の熱的構造と組成に関する重要な洞察を提供した.
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