Experimental Investigations of the Comet Lander Philae Touchdown Dynamics

The comet lander Philae (as part of Europe's Rosetta mission) is en route to its target, 67/P Churyumov-Gerasimenko. With landing operations coming up at the end of 2014, a partial retesting of the Philae lander's touchdown system was carried out in spring of 2013. Intensive testing was performed as part of Philae's design and verification program approximately 10 years ago. However, the new test series specifically addresses touchdown conditions that have been out of capability of the pendulum test facility used at those times. Thus, the follow-up tests focus on touchdown conditions such as asymmetric loads, effects from terrain undulation, and the effect of granular soil mechanics, which could not be studied sufficiently in the original tests. This paper provides insight into the touchdown system of the Philae lander, the characteristics of the used test facility, its weight offloading operating mode, and the specific application to a small-body landing test. The results of the study are presented and discussed in terms of their importance to the ongoing landing preparations.