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).

No abstract

No abstract

Now spanning a time frame of already 10 years, the plan to land a European Lander on an asteroid has finally been accomplished. The first idea was established around 2008 in the framework of the European Marco Polo Assessment, studying the possibility to collect a pristine sample of a Near-Earth Asteroid and returning it back to Earth. The lander named MASCOT (Mobile Asteroid Surface Scout) was proposed to be carried by the main spacecraft, to land on the surface and by the ability to relocate to investigate multiple surface locations in order to scout the best possible sampling site. After the discontinuation of the original study, MASCOT received an invitation from JAXA to join-in the Hayabusa2 mission, the direct follow-up of the first asteroid sampler Hayabusa. However, MASCOT was selected at a time (mid 2011) when its conceptual design and scientific payloads had not been fully defined; with the carrier spacecraft already in its critical design phase having most of its interfaces fixed; no heritage to use off-the-shelf bus equipment directly and only 3 years left until a proposed final delivery. The tight schedule, tightly defined envelope, and strict margins policy were challenges during its development at all levels. Nevertheless, Hayabusa2 and MASCOT were launched on December 3rd, 2014, and arrived at their destined target asteroid (162173) Ryugu on June 27, 2018. Finally, MASCOT was separated from its mother spacecraft and successfully landed on October 3rd, 2018, accomplishing the first ever landing of a European spacecraft on the surface of an asteroid. This paper provides a review of the performed MASCOT development process including its verification strategy from the first unit hardware test to the final check-out before launch. In addition, it also provides a historical comparison to former fast-paced programs in space.