August 14, 2018

Choosing landing site for MASCOT proves “a real challenge”

At CNES in Toulouse, the scientists and engineers working on the Hayabusa2/MASCOT mission have finished identifying and ranking 10 possible landing sites for MASCOT on Ryugu. No easy task…

Finding the best trade-off

Some 40 French, German and Japanese scientists and engineers came together today at CNES in Toulouse to identify the best spot to land MASCOT on asteroid Ryugu. The small 10-kg lander is set to be released early in October from the Japanese Hayabusa2 probe more than 300 million km from Earth. The biggest challenge proved to be meeting the technical and scientific criteria for the mission’s four instruments: the MicrOmega infrared microscope, the MASCAM multispectral camera, the MasMag magnetometer and the MARA radiometer.

Représentation planisphère des 10 sites d’atterrissage de Mascot pré-sélectionnés et présentés par le CNES lors la réunion du 14/08 à Toulouse (zones de probabilité du 1er contact en bleu clair, zones de stabilisation après rebonds en bleu foncé). Les numéros de ces sites sont des références, ils ne sont pas classés par ordre de préférence. Crédits : CNES.

There was very little time to thrash things out…

Choosing from the 10 landing sites pre-selected by CNES was no easy task, and teams had to seek the best trade-off. “There was very little time to thrash things out,” explains Aurélie Moussi-Soffys, MASCOT project leader at CNES. “Obviously, the scientists don’t share the same perspectives, as the four instruments on MASCOT will be looking at very different things. That meant finding a trade-off between science requirements and mission safety, all in just a few hours… that was a real challenge!”

Choice announced on 23 August in Japan

A shortlist of landing sites was established today to find the best combination between the site where MASCOT will land and study the asteroid’s surface and where Hayabusa2 will collect its first samples. The final landing site for MASCOT will then be chosen and officially announced by the Japan Aerospace Exploration Agency (JAXA) at a media briefing in Sagamihara, near Tokyo, on 23 August. MASCOT is scheduled to be dropped onto the surface of Ryugu in the first week of October, but many uncertainties remain about what will happen when it touches the asteroid. Will it bounce, and if so how far? MASCOT’s battery is only designed to last for 15 hours after its release, so the descent trajectory needs to be optimal. And that’s exactly where CNES’s expertise comes in...

The Hayabusa2/MASCOT engineering and science teams debated for several hours on 14 August at CNES to come up with a shortlist of possible landing sites for MASCOT on asteroid Ryugu. Credits: CNES/JAXA/DLR/Rémi Benoît, 2018.

Picture of the surface of asteroid Ryugu taken by the Hayabusa2 probe from just 6 km away at end July. Credits: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.

Laurence Lorda, CNES spaceflight dynamics team lead

“The role of our spaceflight dynamics team at CNES is crucial. We were tasked with proposing an initial list of 10 landing sites for MASCOT based on extremely complex statistical trajectory calculations using our numerical models. To arrive at this result, we worked with our German partners, notably the thermal engineering team at the German space agency DLR, which has extensive expertise dealing with the temperature parameters that are most going to affect MASCOT. In the final analysis, the ideal trajectory is the one that will enable us to do the most science. We have to satisfy all the project scientists and find a trade-off that ensures optimal mission safety. That’s what we succeeded in doing at CNES today. And let’s not forget that what we’re accomplishing here—landing on an asteroid and performing in-situ analysis on its surface—is quite exceptional and something we’re all really proud of!” (Photo credits: CNES/S. Charrier).

About the Hayabusa2 mission

Hayabusa2 is a sample return mission to asteroid Ryugu led by the Japan Aerospace Exploration Agency (JAXA). The French-German MASCOT lander on Hayabusa2 was developed and built by the German space agency DLR, in close collaboration with CNES. The lander’s scientific instruments were developed by DLR, the IAS space astrophysics institute and Braunschweig University of Technology (TUB). MASCOT and its experiments are being operated and controlled by DLR with support from CNES and in constant communication with JAXA.