Letter to the Editor

The descent and bouncing path of the Hayabusa2 lander MASCOT at asteroid (162173) Ryugu

¹ German Aerospace Center (DLR), Institute of Planetary Research, 12489 Berlin, Germany
e-mail: Frank.Scholten@dlr.de
² German Aerospace Center (DLR), Microgravity User Support Center (MUSC), Cologne, Germany
³ Technical University Braunschweig, Institute for Geophysics and Extraterrestrial Physics, Germany
⁴ German Aerospace Center (DLR), Institute of Space Systems, Bremen, Germany
⁵ Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo, Japan
⁶ University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
⁷ Planetary Exploration Research Center, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba, Japan
⁸ Department of Information Science, Kochi University, 2-5-1 Akebono, Kochi, Japan
⁹ Instituto de Astrofisica de Canarias, University of La Laguna, Santa Cruz de Tenerife, Spain
¹⁰ Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, Japan
¹¹ ISAS, JAXA, 3-3-1 Yoshinodai, Chuo, Sagamihara, Kanagawa, Japan
¹² National Institute of Advanced Industrial Science and Technology, 2-3-26 Aomi, Koto, Tokyo, Japan
¹³ Department of Physics, Meiji University, 1-1-1 Higashimita, Tama, Kawasaki, Kanagawa, Japan
¹⁴ CAIST/ARC-Space, University of Aizu, Aizu-Wakamatsu, Fukushima, Japan
¹⁵ Department of Planetology, Kobe University, 1-1 Rokkodaicho, Nada, Kobe, Hyogo, Japan

Received: 23 September 2019
Accepted: 31 October 2019

Abstract

Images from the Optical Navigation Camera system (ONC) onboard the Hayabusa2 spacecraft show the MASCOT lander during its descent to the surface of asteroid (162173) Ryugu. We used results from a previous stereo-photogrammetric analysis that provided precise ONC image orientation data (camera position and pointing), ONC orthoimages, and an ONC-based 3D surface model to combine them with the visibilities of MASCOT itself and its shadow on-ground within the ONC images. We integrated additional information from instruments onboard MASCOT (MASMag, MARA, MASCam) and derived MASCOT’s release position and modeled its free-fall descent path and its velocity over 350 s from its release at ∼41 m altitude above ground until its first contact with the surface of Ryugu. After first contact, MASCOT bounced over the surface of Ryugu for 663 s and came to rest at its first settlement point after four intermediate surface contacts. We again used ONC images that show MASCOT and partly its shadow and reconstructed the bouncing path and the respective velocities of MASCOT. The achieved accuracy for the entire descent and bouncing path is ∼0.1 m (1σ).