Rotational Motion of the Spacecraft Philae During Landing on Comet 67P/Churyumov-Gerasimenko

摘要

This paper presents a partial reconstruction of the rotational dynamics of the Philae spacecraft upon landing on comet 67P/Churyumov-Gerasimenko as part of the European Space Agency's Rosetta mission. The motion is analyzed, as are the events triggered by the failure to fix the spacecraft to the comet surface at the time of the first touchdown. Dynamic trajectories obtained by numerical simulation of a seven-degree-of-freedom mechanical model of the spacecraft are fitted to directions of incoming solar radiation inferred from in situ measurements of the electric power provided by the solar panels. The present results include estimations of the amplitude of precessional motion and a lower bound of the angular velocity of the lander immediately after its first touchdown. The present study also gives insight into the effect of the programmed turnoff of the stabilizing gyroscope after touchdown; the important dynamical consequences of a small collision during Philae's journey; and the probability that a similar landing scenario harms the operability of this type of spacecraft.