ISAS Space Science Colloquium & Space Science Seminar
The Importance of Phobos Sample Return for Understanding Mars
Martian rocks span a wide range of physical and geologic properties, ranging from dense, crystalline igneous rocks to soft, mechanically weak sediments. They also span a wide range of ages, covering most of the 4. 5-billion-year history of the planet. The SNC meteorites that have arrived on Earth as ejecta from Mars are heavily biased toward strong crystalline materials that can survive high speed ejection. Rocks collected from the martian surface by robotic sample return missions will be biased toward ancient, highly localized sedimentary and aqueous mineral deposits that might preserve evidence of ancient life.
To understand Mars fully, there is a need for a samples that are more broadly representative of the martian crust as a whole. Such samples can be obtained from martian ejecta in the regolith of the martian moons, particularly Phobos. The flux of martian ejecta at Phobos has increased sharply over time as Phobos' orbit has decayed due to tidal forces, so most martian ejecta will be concentrated in the upper meter of the regolith. Martian ejecta on Phobos will include debris accelerated to much lower velocities than SNC meteorites, and therefore should include materials weaker than SNC meteorites. And martian ejecta on Phobos will be from sites distributed widely across the planet. So in addition to revealing the origin of the martian moons, return of a regolith sample from Phobos may provide martian materials that are highly complementary to both SNC meteorites and Mars surface samples.
Place: Shin-A 2F Conf room A （1257） / 新A棟2階会議室A （1257号室）