Thermophysical modeling of Didymos' moon for the Asteroid Impact Mission

Abstract Although typically less resolved through observations, the secondary in a binary system of asteroids is an interesting target for space missions such as the Asteroid Impact Mission. Estimates of the surface temperature distribution are important for mission design. Based on known, assumed and derived physical properties, a thermophysical model of the smaller body in the 65803 Didymos system is established. Because of the unknown thermal inertia, a parameter study has been carried out for a thermal inertia range of Γ = 50 –1000 J m −2  K −1  s −1/2 . Results are presented for the minimum and maximum values of this range and a likely value of Γ = 500  J m −2  K −1  s −1/2 . The parameter study extends from the unshadowed to the eclipsed case where shadowing through the primary is simulated in a simplified manner assuming that the orbit of the moon lies in the equatorial plane of the primary with its z -axis normal to this plane. Results from this study are used to investigate performance for instruments foreseen for the Asteroid Impact Mission. Preliminary results are obtained for the signal-to-noise ratio of a proposed thermal infrared imager. Furthermore, MASCOT-2 Lander thermal survivability has been investigated for several possible landing sites and specific settings.