ELSI Seminar

Ryuki Hyodo
July 31, 2018

Formation of small bodies, planetesimals and planets: Bridging theoretical studies and JAXA's planetary explorations
Small bodies have been the targets of JAXA's planetary explorations (such as HAYABUSA, HAYABUSA 2 and Martian Moons eXploration (MMX) missions). Planetary explorations can bring the crucial information about the history of solar system evolution. However, when we look back at the history of JAXA's planetary explorations, the missions are mainly driven by engineering side and the science was not fully maximized especially before the launch and before the arrivals of the spacecraft to the targets.

What is, now, needed for JAXA's ongoing and future explorations is that a scientist(s) that can bridge science and engineering or/and that can propose science-driven explorations so that we can maximize not only technological development but also science through planetary explorations. I'm now officially involved in, at least, two JAXA's planetary explorations (HAYABUSA 2 and MMX) as a member of science teams. HAYABUSA 2 has just arrived at Ryugu (C-type asteroid) and will bring the sample back to the Earth in 2021. MMX will be launched in 2024 and go to Martian moon to return samples back to the Earth. So, it's very important moment to work on these missions.

In ELSI, I myself will work on theoretical studies about the formation and evolution of planetary systems. Especially, I will study formation/evolution of (1) small bodies such as moons and asteroids (targets of ongoing JAXA's explorations), and (2) planetesiamls and planets (future targets of JAXA's explorations). And, I will try to bridge the above scientific works and the planetary explorations.

In the talk, I will explain/discuss two things: (1) the current understandings on the origin/evolution of Martian moons (e.g. Hyodo et al. 2017a,b, Hyodo&Genda 2018) and its connection with MMX mission and (2) the importance to study the formation of planetesimals (e.g. Hyodo&Ida in prep). Planetesimals are the fundamental building blocks of all planets and small bodies that could be formed from micron-sized dusts. Even though we know several physical processes that can potentially create planetesimal, we still do not know if we can apply these processes to the real world because they require specific conditions. Thus, understanding "location", "timing" and "conditions" (such as chemical and thermal environment) that can form planetesimals are the key to understand very early conditions of the building blocks of planetary bodies. In the talk, I will address how to tackle these problems and how we can link them to the ongoing and future JAXA's explorations.