Egress is mission-critical because even journeys of a thousand miles begin with a first step. The first step for a rover is always getting off the lander. For missteps, there is usually no going back. Gravity facilitates egress, because egress steps off and down. Terrain can confound egress, since a lander can be tilted by slope or rocks.

How does this rover always egress downward? By steering on its lander to reach a good slope and step before rolling onto the moon. The tests are done in earth gravity with a skeletal rover. Earth-test with a light rover simulates moon gravity with a full-mass rover.