Power Production for Small Body Landers: Post-Launch Activities on Philae's Power Subsystem

Producing power with solar arrays for small-body landers is a challenging task as the possible low-intensity, low-temperature environment, together with possible dust deposition and ice condensation, worsen not only the production of power but also make it difficult to formulate predictions on the subsystem's performances. Moreover, the motion of the target body (both orbital and attitude dynamics), its landscape, the landing site location, and the lander orientation further increase the level of uncertainties that characterize the daily power profile. On the other hand, the lander survival and the ultimate mission goals strictly depend on the ability of Philae of being able to produce enough power to feed the system and to recharge the batteries. In this note we discuss issues related to the power production via solar arrays for small-body landers. The experience gained in the post-launch activities on Philae's solar arrays is reported. To overcome the above-cited problematics, solutions in terms of hardware and software tools have been developed for power estimation and simulation. These are briefly discussed in this paper, together with ongoing activities and open problems. Although these solutions are reported for the case of Rosetta lander Philae, they apply for possible future missions aimed at performing in-situ operations on comets, asteroids, and distant planets.