月面の南極で厚い氷の堆積がある証拠はない
Donald B Campbell1, Bruce A Campbell, Lynn M Carter
1Department of Astronomy, Cornell University, Ithaca, New York 14853, USA. campbell@astro.cornell.edu
Nature
|October 20, 2006
まとめ
新しいレーダー画像は,月のシャクルトンクレーターで濃縮された水氷の埋蔵物が存在しないことを示しています. 極化特性は,氷ではなく地表の岩石を示唆し,レーダー信号を説明し,将来の月面ミッションの仮定に挑戦しています.
科学分野:
- 月科学は月科学である.
- 惑星地質学 惑星地質学
- リモートセンシングによる遠隔感知
背景:
- 月の南極にあるシャクルトンクレーターには,凝縮された水氷の埋蔵が可能な可能性がある.
- 以前のレーダー研究とモデリングは,極地の冷凍トラップに水氷が存在することを示唆していた.
- 極地で検出された水素増強は,種の識別と分布に関するデータが不足しています.
研究 の 目的:
- 高解像度のレーダーデータを用いてシャクルトンクレーターにおける水氷の存在と分布を調査する.
- レーダー散乱特性,恒久的な影の領域,月の地形の特徴との関係を決定する.
- 水氷の存在を推論するためにレーダー偏振特性を使用する有効性を評価する.
主な方法:
- 月面南極の20m解像度,13cm波長レーダー画像の収集と分析.
- レーダー極化特性の検討と,表面の特徴と太陽光照明との相関.
- 新しいレーダーデータと以前の発見と水素分布データとの比較.
主要な成果:
- シャクルトンクレーターや他の南極地域では,濃縮された水氷の埋蔵の証拠は見つかりませんでした.
- 観測されたレーダー極化特性は,典型的には氷と関連しており,岩石のクレーター壁と噴出物と強く相関しています.
- 偏振特性と太陽光照射の度合いは相関関係がないことが判明しました.
結論:
- シャクルトンクレーターで濃縮された水氷の存在は,新しいレーダーデータによって支持されていません.
- レーダー散乱特性は,広範囲に広がる氷よりも,表面地質,特に岩石地帯の影響を受ける可能性が高い.
- 水素増強が水氷を示しているなら,それは月球のレゴリットの中に粒として拡散している可能性があり,濃縮された堆積物として拡散していない.
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