土星 の 環 から 大気 に 落ちる 塵 の 粒 を 地元 で 収集 する
Hsiang-Wen Hsu1, Jürgen Schmidt2, Sascha Kempf3
1Laboratory for Atmospheric and Space Physics, University of Colorado-Boulder, Boulder, CO, USA. sean.hsu@lasp.colorado.edu.
まとめ
土星のリングは 氷だけではありません カッシーニ宇宙船のデータは 水の氷だけでなく シリケート粒子が 土星に落下していることを明らかにし リングの組成に関する以前の仮定に挑戦しています
科学分野:
- 惑星科学
- 宇宙 塵 の 分析
- 土星系動態
背景:
- 土星の主要なリングは主に水氷 (>95%) です.
- 残りの数パーセントのリング材料の組成は不確かである.
- 以前の研究では リングから土星に降る"リングの雨"を推論していました
研究 の 目的:
- 土星の主要環から生じる物質を直接検出し特徴づけること
- インサイト測定を用いてインフォリング材料の組成を分析する.
- 土星の環の中の非氷の構成要素の性質を明らかにする.
主な方法:
- カッシーニ宇宙船の宇宙塵分析器 (CDA) 衝突質量スペクトロメーターを使用した.
- 土星とD環の間を通過する際の塵の粒を集めて分析した.
- 検出された粒子の大きさ,組成 (水氷,シリケート),動態を特徴付けました.
主要な成果:
- 土星の主要環から放出されたナノメートルサイズの粒子を 直接検知します
- 水氷とシリケート粒子の識別
- シリケート粒は,リングのシリケート含有量を超えて,最大30%のシリケート粒で構成されています.
結論:
- 土星の環には,これまで過小評価されていた重要な非氷 (シリケート) 成分が含まれています.
- 検出されたシリケート粒子は,土星に衝突する"リングの雨"現象に寄与しています.
- これらの発見は,リングの組成と進化のモデルの見直しを必要とします.
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