Surface evolution of small bodies of the solar system by space weatheirng and thermal fatigue

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01267
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Osaka University
• Principal Investigator: Sasaki Sho 大阪大学, 理学研究科, 教授 (10183823)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 宇宙風化作用 / 熱疲労 / はやぶさ２ / 反射スペクトル / 炭素質隕石 / 暗化 / 含水鉱物 / リュウグウ

Outline of Final Research Achievements

The current diffuse reflection measurement system was modified to measure down to 3.4 microns, and measurements of the CM2 carbonaceous meteorite show a slight weakening of the 3-μm absorption band after laser irradiation and an overall weakening and reddening of the spectrum. The color of recently formed craters is relatively blue in Ryugu (Morota et al., 2020). This is consistent with our results.
Regarding ultraviolet irradiation, an interesting result is that the visible region of olivine darkens in a short period of time. Even in space, a reflectance decrease of several 10% is expected after a few days of irradiation.　Cracks in the rocks on the surface of Ryugu are predominantly in the north-south direction, which may be due to thermal fatigue.

Free Research Field

惑星科学

Academic Significance and Societal Importance of the Research Achievements

はやぶさ２による炭素質小惑星リュウグウの探査は、地球惑星科学や宇宙工学にとどまらず、広い分野にインパクトを与えている。科学成果を最大化するために、ミッションデータ解析や地上実験のサポートは意義が高く不可欠である。我々のCM2炭素質隕石の測定では、レーザー照射後は3μmの吸収帯が少し弱くなること、全体的にスペクトルが弱く赤化する。最近形成されたクレーターの色はリュウグウでは相対的に青く(Morota et al., 2020)これは、我々の結果と整合的であり、研究の学術的意義の高さを示す。