Design and Verification of the GNC for the European ExoMars EDL Demonstrator

Disturbance rejection in space applications: Problems and solutions

“…Fig. 1 shows the commanded acceleration a uz in ( 16) and the open-loop component a uz in (15). The latter which is the sum of the ground Mars gravity g and of a 'constant' braking acceleration, holds…”

“…Soft landing requires that the velocity magnitude v ¼9v9 be brought to zero and the vehicle axis tends to be vertical at the terminal time t f corresponding to a prespecified altitude h f from ground. If touch-down is softened either by air bags, crushable structures (ExoMars landing demonstrator [15]), or damping legs, then the thrusters controlling the vehicle braking are switched off at t f . If the vehicle landing is planned in such a way that it is to hover over the landing site, such as in the case of the US Mars Science Laboratory [16], thrust is lowered so as to simply compensate for local gravity.…”

“…As a concise proof, replace (16) into the top equation of (11) thus canceling d a þd s . Then subtract the remaining equation from (15), thus canceling a u which results in (17).…”

Powered-descent landing GNC system design and flight results for Tianwen-1 mission

“…In the previous Mars landing mission, the powered-descent phase of ExoMars 2016 was responsible for performing the backshell avoidance maneuver and deceleration [9]. The powered-descent phase of the Mars Science Laboratory and Mars 2020 was responsible for removing the final 0.1% of the kinetic energy; performing a 300-m out-of-plane divert maneuver to avoid collision with the backshell and parachute; and gently placing the rover on the surface using the skycrane maneuver [10,11].…”