[P-CG18] Future missions and instrumentation for space and planetary science

[PCG18-09] The Next Generation Small Body Sample Return: Science Working Group Status Report

*Hiroyuki Kurokawa¹, Yuri Shimaki², Naoya Sakatani², Ryota Fukai², Yoko Kebukawa³, Jun Aoki⁴, Eri Tatsumi⁵, Shigeru Wakita⁶, Takayuki Ushikubo⁷, Atsushi Kumamoto⁸, Hideaki Miyamoto⁹, Taichi Kawamura¹⁰, Satoshi Tanaka², Takeshi Tsuji⁹, Seitaro Urakawa¹¹, Ryou Ohsawa¹², Yuichi Tsuda², Osamu Mori², Yusuke Maru², Takanao Saiki², The Next Generation Small Body Sample Return WG (1.Tokyo Institute of Technology, 2.Japan Aerospace Exploration Agency, 3.Yokohama National University, 4.Osaka University, 5.Instituto de Astrofísica de Canarias, 6.Massachusetts Institute of Technology, 7.Japan Agency for Marine-Earth Science and Technology, 8.Tohoku University, 9.University of Tokyo, 10.Université Paris Cité/Institut de Physique du Globe de Paris, CNRS, 11.Japan Spaceguard Association, 12.National Astronomical Observatory of Japan)

Keywords:The Solar-System Exploration, Small Bodies, Comets

The Next Generation Small Body Sample Return (NGSR) mission is a future solar-system exploration mission for sample return from a solar system small body under consideration. In February 2023, we newly launched the Science Working Group (WG) for the NGSR mission. The Science WG studies science goals and mission payloads of the NGSR. In collaboration with the Engineering WG, the Science WG aims to propose the NGSR as a strategic middle-class mission which will be launched in 2030s by ISAS, JAXA.

The NGSR targets a comet to bring back its subsurface materials and to explore its surface and internal structure. The Science WG defined the NGSR as a mission to unveil the origin of the solar system, namely, I) the origin of the solar-system “materials” in galactic evolution and II) the origin of the solar-system “bodies” to form planetesimals. For those science goals, we categorize science objectives as follows: Science objective I-1) unveiling the types of parent stars of the solar-system materials and their fractions, I-2) elucidating the origins of cometary organic matters, II-1) clarifying whether comets are rubble-pile or a pebble-pile bodies, and II-2) elucidating the formation environment of comets.

Science Goal I can be mainly achieved by sampling and analysis of subsurface materials of the target comet. In contrast to surficial materials that experienced alteration caused by space weathering and cometary activities, subsurface materials are thought to be pristine record of the original solar-system building blocks and, consequently, of the evolution of materials in our galaxy. Excavating and sampling subsurface materials are needed. Moreover, we are planning to install a mass spectrometer for in situ analysis of volatile materials that will potentially be altered and/or lost before the sample recovery.

Science Goal II can be mainly achieved by physical explorations of the interior structure with a radar and seismometer. Pebble-pile bodies (pristine first-generation of planetesimals) and rubble-pile bodies (disrupted and re-accreted planetesimals) should have different interior structures; only the latter are thought to possess meter-scale internal voids. The meter-scale heterogeneity can induce different propagation and reflection patterns for both radio and seismic waves.

In this presentation, we report the current status and future plans of the Science WG activities.