Asteroids, , Meteors - ACM2017 - Montevideo

THE PHILAE LANDING – LESSONS LEARNED FOR FUTURE SMALL BODIES MISSIONS 1 1 S. Ulamec and J. Biele 1German Aerospace Center - DLR, MUSC, Linder Höhe, 51147 Cologne, Germany [email protected]

Introduction and Overview: The There are also aspects from a programmatic Philae was part of the ESA mis- point of view, where the Philae project can sup- sion [1]. It successfully landed on comet port the planning and designing of future mis- 67P/Churyumov-Gerasimenko on November sions. 12th, 2014 [2]. The landing followed a careful Philae was a multi-lateral, long term project landing site selection process based on data ob- facing challenges regarding an appropriate tained with the Rosetta orbiter instruments [3]. management structure as well as its knowledge After several (unplanned) bounces, Philae per- management strategy [5]. formed a First Scientific Sequence (FSS), based on the energy stored in it’s on-board batteries. Small Payloads for future small bodies mis- The touch-down dynamics, bouncing trajectory sions: Philae is avery complex, about 100 kg and attitude could be reconstructed a-posteriori. lander with a sophisticated payload, but there Philae has a payload of ten scientific instru- are options for smaller (and less expensive) de- ments, all of which have been operated at least vices, still capacle of providing important data once [4]. from an ´s or comets surface. Due to the fact that the final landing site was One example is MASCOT, a small (about 10 poorly illuminated, Philae went into hibernation kg) surface package, currently aboard the after FSS, but signals from the Lander were JAXA 2 spacecraft on its way to as- received again in June and July 2015. Howev- teroid (162173) Ryugu [6]. er, attempts to re-establish reliable and stable Other small lander designs, partly based on communications links, unfortunately, failed. MASCOT are currently considered for e.g. the September 2nd, 2016, shortly before the Rosetta planned missions AIM/AIDA (asteroid mitiga- mission was ended with a planned impact of the tion demonstration) [7], MarcoPolo M5 (a pro- main spacecraft, Philae could be clearly identi- posal for the ESA program) or MMX fied on the comet surface with the Rosetta Or- (planned JAXA mission to Phobos). biter Camera (OSIRIS). Rosetta is an ESA mission with contributions Acknowledgments: The authors would like to from its member states and NASA. Rosetta's thank the complete Philae team, including the Philae Lander is provided by a consortium led teams responsible for the subsystems and in- by DLR, MPS, CNES and ASI with additional struments as well as the Philae Steering Com- contributions from Hungary, UK, Finland, Ire- mittee for making this mission possible. Partic- land and Austria. ular thanks go to ESA for supporting the Lander whenever possible. Lessons Learned from Philae Mission: Ro- setta was the first spacecraft working for an References: [1] Glaßmeier K.-H. et al. (2007) extended period of time in the vicinity of a Space Sci. Rev. 128, 1–21. [2] Biele J. et al. comet and Philae was the first device to actual- (2015) Science 349, aaa9816. [3] Ulamec S. et ly land on a . A tremendous al. (2015) Acta Astron., 107, 79-86. [4] Ula- amount of information on the of comets mec S. et al. (2016) Acta Astron., 125, 80-91. has been obtained, allowing future comet mis- [5] Ulamec S. et al. (2010) 3rd Internat. Conf. sions to be adapted to this previously poorly on Knowledge Management., ESA/ESOC, known environment. Germany. [6] Ho T.-M. et al. (2016) Space Regarding the interaction with the surface, one Sci. Rev., DOI 10.1007/s11214-016-0251-6. of the surprising results of the Philae measure- [7] Cheng A. et al. (2015) Acta Astron., 115, ments (and the bouncing itself) is the high 262-269. strength of the surface material [2].