Japan Geoscience Union Meeting 2023

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[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-OS Ocean Sciences & Ocean Environment

[A-OS14] Continental Oceanic Mutual Interaction - Planetary Scale Material Circulationn

Wed. May 24, 2023 1:45 PM - 3:00 PM Exhibition Hall Special Setting (3) (Exhibition Hall 8, Makuhari Messe)

convener:Yosuke Alexandre Yamashiki(Earth & Planetary Water Resources Assessment Laboratory Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University), Swadhin Behera(Application Laboratory, JAMSTEC, 3173-25 Showa-machi, Yokohama 236-0001), Takanori Sasaki(Department of Astronomy, Kyoto University), Yukio Masumoto(Graduate School of Science, The University of Tokyo), Chairperson:Takanori Sasaki(Department of Astronomy, Kyoto University), Yosuke Alexandre Yamashiki(Earth & Planetary Water Resources Assessment Laboratory Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University)

2:45 PM - 3:00 PM

[AOS14-05] Impact risks of small Solar System bodies for the Earth-Moon and Mars

★Invited Papers

*Makoto Yoshikawa1 (1.Japan Aerospace Exploration Agency)

Keywords:planetary defense, Earth collision, Near-Earth Object, orbit

About 30 years have passed since the beginning of the 1990s when Spaceguard began full-scale discussions on the issue of small solar system bodies such as asteroids and comets colliding with Earth. During this time, the discovery of near-Earth objects has progressed, and at present, about 30,000 near-Earth objects called NEOs (Near-Earth Objects: definition is that the perihelion distance is less than 1.3au) have been discovered. In addition, explorations to NEO are being carried out one after another, and spacecraft has been approached 10 NEOs. Currently, under the name of planetary defense, the problem of collisions of celestial bodies with the Earth is being widely and actively studied internationally. The studies up to now have been about collisions of celestial bodies with the Earth, but considering that human beings will advance to the moon and Mars in the future, we will also consider collisions of celestial bodies on the Moon and Mars. Since the Moon is close to the Earth, the study of collision with the Earth includes the collision with the Moon. However, actual impact events would be quite different from the point of view of risk, as the Moon does not have an atmosphere like Earth does. Mars, on the other hand, has a greater risk of collision than the Earth-Moon because of its proximity to the asteroid belt. For example, if we examine the asteroids whose orbits are known at present ignoring the spatial direction of the orbits, we can find that there are about 50,000 asteroids that intersect the orbit of Mars. As for the Earth, this number is about 20,000. Considering the selection effect that the observations are made from the Earth, we can imagine that the collision risk of celestial bodies on Mars is much higher than on the Earth. In this talk, we discuss the impact risks of small bodies on the Earth-Moon and Mars, especially from the point of view of the orbits.