Direct Observations of Asteroid Interior and Regolith Structure: Science Measurement Requirements

Alain Hérique (1) , Benoit Agnus , Erik I. Asphaug (2) , Maria Antonella Barucci (3) , Pierre Beck (1) , Julie Bellerose (4) , Jens Biele (5) , Lydie Bonal (1) , Pierre Bousquet (6) , Lorenzo Bruzzone (7) , Christopher Buck (8) , Ian Carnelli (9) , Andrew Cheng (10) , Valérie Ciarletti (11) , Marco Delbo (12) , J. Du (13) , X. Du (14) , Christelle Eyraud (15, 16) , W. Fa (13) , Jesus Gil-Fernandez (8) , Oriane Gassot (1) , Ricardo Granados-Alfaro (1) , Simon F. Green (17) , B. Grieger (18) , Jan Thimo Grundmann (19) , J. Grygorczuk (20) , Ronny Hahnel (14) , Essam Heggy (4, 21) , T.-M. Ho (19) , Özgür Karatekin (22) , Y. Kasaba (23) , T. Kobayashi (24) , Wlodek Kofman (1, 25) , C. Krause (5) , A. Kumamoto (23) , Michael Küppers (18) , M. Laabs (14) , C. Lange (19) , Jérémie Lasue (26) , Anny Chantal Levasseur-Regourd (11) , A. Mallet (6) , P. Michel (12) , Stefano Mottola (19) , N. Murdoch (27) , Marco Mütze (14) , J. Oberst (28) , Roberto Orosei (29) , Dirk Plettermeier (30) , Sylvain Rochat (1) , Raquel Rodriguez-Suquet (6) , Yves Rogez (1) , P. Schaffer (14) , Colin Snodgrass (31) , Jean-Claude Souyris (6) , M. Tokarz (20) , Stephan Ulamec (5) , Jan-Erik Wahlund (32) , Sonia Zine (1)

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
2 SESE - ASU School of Earth and Space Exploration
3 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
4 JPL - Jet Propulsion Laboratory
5 DLR - Deutsches Zentrum für Luft- und Raumfahrt
6 CNES - Centre National d'Études Spatiales [Toulouse]
7 University of Trento [Trento]
8 ESTEC - European Space Research and Technology Centre
9 ESA - Agence Spatiale Européenne = European Space Agency
10 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
11 PLANETO - LATMOS
12 LAGRANGE - Joseph Louis LAGRANGE
13 Peking University [Beijing]
14 TU Dresden - Technische Universität Dresden = Dresden University of Technology
15 FRESNEL - Institut FRESNEL
16 HIPE - HIPE
17 PSS - Planetary and Space Sciences [Milton Keynes]
18 ESAC - European Space Astronomy Centre
19 DLR Institut für Planetenforschung
20 ASTRONIKA Sp. Zo.o.
21 USC Viterbi School of Engineering
22 ROB - Royal Observatory of Belgium [Brussels]
23 Tohoku University [Sendai]
24 Korea Institute of Geoscience and Mineral Resources
25 CBK - Space Research Centre of Polish Academy of Sciences
26 IRAP - Institut de recherche en astrophysique et planétologie
27 ISAE-SUPAERO - Institut Supérieur de l'Aéronautique et de l'Espace
28 TU - Technical University of Berlin / Technische Universität Berlin
29 IRA - Istituto di Radioastronomia [Bologna]
30 IfN - Institut für Nachrichtentechnik [Dresden]
31 School of Physical Sciences [Milton Keynes]
32 IRF - Swedish Institute of Space Physics [Uppsala]

Our knowledge of the internal structure of asteroids is, so far, indirect – relying entirely on inferences from remote sensing observations of the surface, and theoretical modeling of formation and evolution. What are the bulk properties of the regolith and deep interior? And what are the physical processes that shape asteroid internal structures? Is the composition and size distribution observed on the surface representative of the bulk? These questions are crucial to understand small bodies’ history from accretion in the early Solar System to the present, and direct measurements are needed to answer these questions for the benefit of science as well as for planetary defense or exploration. Radar is one of the main instruments capable of sounding asteroids to characterize internal structure from sub-meter to global scale. In this paper, we review the science case for direct observation of the deep internal structure and regolith of a rocky asteroid of kilometer size or smaller. We establish the requirements and model dielectric properties of asteroids to outline a possible instrument suite, and highlight the capabilities of radar instrumentation to achieve these observations. We then review the expected science return including secondary objectives contributing to the determination of the gravitational field, the shape model, and the dynamical state. This work is largely inherited from MarcoPolo-R and AIDA/AIM studies.

Keywords: Near-Earth Asteroid; Radar Tomography; Dielectric properties; Asteroid deep internal structure; Asteroid regolith

Domains: Neuroscience; Earth and Planetary Astrophysics [astro-ph.EP]

Alain Hérique, Benoit Agnus, Erik I. Asphaug, Maria Antonella Barucci, Pierre Beck, et al.. Direct Observations of Asteroid Interior and Regolith Structure: Science Measurement Requirements. Advances in Space Research, 2018, 62 (8), pp.2141-2162. ⟨10.1016/j.asr.2017.10.020⟩. ⟨insu-01624991⟩