System Configuration and Operation Plan of Hayabusa2 DCAM3-D Camera System for Scientific Observation During SCI Impact Experiment

• Published in: Space science reviews 2017-07, Vol.208 (1-4), p.125-142
• Main Authors: Ogawa, Kazunori, Shirai, Kei, Sawada, Hirotaka, Arakawa, Masahiko, Honda, Rie, Wada, Koji, Ishibashi, Ko, Iijima, Yu-ichi, Sakatani, Naoya, Nakazawa, Satoru, Hayakawa, Hajime
• Format: Article
• Language: English
• Subjects: Aerospace Technology and Astronautics; Asteroids; Astrophysics and Astroparticles; Cameras; Configurations; Control equipment; Data storage; Ejecta; Experiments; Japanese spacecraft; Microgravity; Optical observations; Physics; Physics and Astronomy; Planetology; Projectiles; Radio communications; Space Exploration and Astronautics; Space rendezvous; Space Sciences (including Extraterrestrial Physics; Spacecraft; Systems design
• ISSN: 0038-6308; 1572-9672
• DOI: 10.1007/s11214-017-0347-7

An artificial impact experiment is scheduled for 2018–2019 in which an impactor will collide with asteroid 162137 Ryugu (1999 JU 3 ) during the asteroid rendezvous phase of the Hayabusa2 spacecraft. The small carry-on impactor (SCI) will shoot a 2-kg projectile at 2 km/s to create a crater 1–10 m in diameter with an expected subsequent ejecta curtain of a 100-m scale on an ideal sandy surface. A miniaturized deployable camera (DCAM3) unit will separate from the spacecraft at about 1 km from impact, and simultaneously conduct optical observations of the experiment. We designed and developed a camera system (DCAM3-D) in the DCAM3, specialized for scientific observations of impact phenomenon, in order to clarify the subsurface structure, construct theories of impact applicable in a microgravity environment, and identify the impact point on the asteroid. The DCAM3-D system consists of a miniaturized camera with a wide-angle and high-focusing performance, high-speed radio communication devices, and control units with large data storage on both the DCAM3 unit and the spacecraft. These components were successfully developed under severe constraints of size, mass and power, and the whole DCAM3-D system has passed all tests verifying functions, performance, and environmental tolerance. Results indicated sufficient potential to conduct the scientific observations during the SCI impact experiment. An operation plan was carefully considered along with the configuration and a time schedule of the impact experiment, and pre-programed into the control unit before the launch. In this paper, we describe details of the system design concept, specifications, and the operating plan of the DCAM3-D system, focusing on the feasibility of scientific observations.