An Algorithm for Safe Landing of a Spacecraft during Descent from a Circumlunar Orbit

Abstract

The problem of safe landing of a spacecraft with a combined propulsion system from a circumlunar orbit to a given place on the lunar surface is considered. Landing safety is ensured by the implementation of restrictions on the motion parameters at the time of landing, as well as the possibility of horizontal displacement of the spacecraft relative to the lunar surface to correct the landing place, taking into account the slope, the absence of large stones, and deep pits. The descent-control algorithm uses the solution to the free fall‑braking model problem. The proportional guidance algorithm is used to correct the landing place. Adaptation to the actual magnitude of the apparent acceleration is carried out. Statistical tests have shown the efficiency of the algorithm, an estimate of the accuracy of lending and propellant consumption has been obtained, taking into account all restrictions on the operation of the propulsion system under the conditions of a safe lunar landing.