ヨーロッパの差別化された内部構造: 4つのガリレオの遭遇から得られた推論
J D Anderson1, G Schubert, R A Jacobson
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
Science (New York, N.Y.)
|September 25, 1998
まとめ
ガリレオ宇宙船のデータは,木星のモデルを改良する.
科学分野:
- 惑星科学は惑星科学である.
- アストロジオロジー アストロジオロジー
- 地質物理学 地質物理学とは地質物理学です.
背景:
- 木星の衛星であるヨーロッパは,地球外生命の探求における重要なターゲットである.
- エウロパの内部構造を理解することは,その居住性を評価する上で極めて重要です.
- 以前のモデルでは,異なる内部が示唆されていたが,直接的な証拠は限られていた.
研究 の 目的:
- ラジオドップラーデータを用いて,ヨーロッパの内部構造のモデルを精製する.
- ヨーロッパのコアとマントルの可能な構成と範囲を制限する.
- エウロパの氷と液体の水殻の外側の厚さを測定するために.
主な方法:
- ガリレオ宇宙船が4回ヨーロッパと遭遇した際に収集されたラジオドップラーデータの分析.
- 宇宙船の軌道の偏差を解釈するために地球物理モデリングの適用.
- 観測されたデータを,様々なインテリアモデルの予測と比較する.
主要な成果:
- ユーロパは,金属の核,シリケートマント,そして外側の氷の液体殻に分けられている可能性が高い.
- 液体氷の殻の下にあるシリケートと金属の均一な混合物は排除できない.
- ユーロパの金属核は半径の50%ほどの大きさになる可能性がある.
- 液結氷外殻の厚さは80~170キロメートルと推定されている.
結論:
- ヨーロッパの内部構造は複雑で,現在のデータでは完全に解明されていない.
- 厚い氷の液体殻によって示される地下海洋の可能性は,ヨーロッパの天体生物学的な関心を支持しています.
- ヨーロッパの核の構成と内部差異を完全に特徴付けるために,さらなる観察とモデリングが必要である.
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