ガニメデの質量異常を発見した

John D Anderson¹, Gerald Schubert, Robert A Jacobson

¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA. john.d.anderson@jpl.nasa.gov

Science (New York, N.Y.)

|August 18, 2004

まとめ

科学者たちは,ガニメデ,木星で驚くべき質量異常を発見しました.

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:

ガニメデは木星の最大の月で,太陽系の氷の衛星である.
質量分布を理解することは,大きな衛星の内部構造と進化を理解するために不可欠です.

研究の目的:

ガニメデの表面で検出された原因不明の質量異常を調査しモデル化するために.
ガリレオ宇宙船からのラジオドップラーデータを分析して,質量変動の源を特定する.

主な方法:

ガリレオ宇宙船がガニメデとの二度目の遭遇 (1996年9月6日) で収集したラジオドップラーデータを利用した.
ドップラーデータに基づいて観測された質量異常を説明するモデルを開発した.

主要な成果:

2つの異なる表面質量異常を特定しました:高緯度での正質量異常と低緯度での負質量異常です.
これらの異常は,観測されたラジオドップラーデータを説明するのに十分であった.
明らかに地質学的な特徴は検出された質量異常と相関していない.

結論:

ガニメデの有意な質量異常の存在は,大きな氷の衛星に対する期待に異議を唱える.
この発見は,地表密度の変動が地表地質学と直接関連していないことを示唆している.
これらの質量異常の起源を特定するために,さらなる調査が必要である.

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