An asteroid up close
In December 2014, the Japanese mission Hayabusa-2 was launched to the 950 meter wide asteroid Ryugu and reached it around three and a half years later. In addition to taking soil samples and transporting them back to Earth, the deployment of small landers was one of the main objectives of the mission. Here we report on the mission of the Franco-German MASCOT probe.
On board Hayabusa-2 was the MASCOT experiment package, the "Mobile Asteroid Surface Scout", a Franco-German lander. She had no wheels, but was still mobile and had a sense of direction. The landing module developed by the German Aerospace Center (DLR) in cooperation with the French "Centre National d'Études Spatiales" (CNES) was able to move on the surface of the asteroid using an internal swing arm (see box on p.32). For example, MASCOT carried out measurements at different points – nothing like this has ever happened.
The first use of such a bouncing lander worked brilliantly, providing evidence that the technique works on small, low-gravity asteroids. Most importantly, MASCOT sent important scientific data directly from the surface of Ryugu, one of the Apollo-type near-Earth asteroids (see box p. 34).
MASCOT landed safely on the small celestial body in the early morning of October 3, 2018 at 2:59 a.m. CEST. The probe first completed a full measurement cycle of all instruments over one asteroid day and one asteroid night. A day-night cycle on Ryugu is 7 hours and 36 minutes. After a "mini-move", a small jump of three and a half centimetres, MASCOT recorded several additional image sequences. Three-dimensional images of the surface could be generated from them, which made it possible to determine distances and sizes. During the first maneuvers, MASCOT moved a few meters to the next measuring point. Finally, the researchers dared to take a bigger leap. …