MASCOT - PREPARATIONS FOR ITS LANDING IN 2018: A STATUS UPDATE FROM GROUND AND SPACE ONE YEAR AHEAD OF THE LANDING ON RYUGU

摘要

Launched in December 2014 the Japanese spacecraft Hayabusa2 (HY2) and its small passenger MASCOT (Mobile Asteroid surface SCOuT) have meanwhile successfully performed more than half of their 4-year-long voyage to reach their target body, asteroid (162173) Ryugu, formerly referred to as 1999 JU_3. While Hayabusa2 is aiming to characterize Ryugu on a global scale and to return samples to Earth, MASCOT's mission is to land on the surface, perform in-situ investigations and thus provide ground truth and context information for the overall Hayabusa2 science activities. The lander was jointly developed by the German Aerospace Centre (DLR) and the Centre National d'Etudes Spatiales (CNES). It is equipped with a sensor suite of four scientific instruments: a hyperspectral IR spectrometer (MicrOmega, IAS Paris), a camera (MasCam, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MasMag, TU Braunschweig) to investigate Ryugu's surface structure, composition and physical properties including its thermal behaviour and magnetization. The planned on surface sequence of measurements will be repeated in a different site after MASCOT's relocation on the asteroid surface. Therefore a mobility subsystem was developed to make MASCOT jump due to applied angular momentum of an eccentric rotating mass inside the system. Since the characteristics of Ryugu such as the exact orientation of the rotation axis, the thermal conditions, shape and surface structure will be known only after arrival of Hayabusa2 in July 2018 there will be only a few weeks available to select a landing site and refine the specific MASCOT mission parameters according to the conditions found, before the landing can take place, in October 2018. MASCOT's on-asteroid lifetime is limited by the capacity of its primary battery which is the main driver to make maximum use of the given time. In order to prepare MASCOT's operation within these constraints, both, space and ground systems have to be well prepared