Descent and Landing

Descent and landing sequence

Descent and landing operations would be based on the following scenario:

• Descent to a minimum-altitude circular orbit (50x50 km), maintained for typically five revolutions.

• De-orbit burns to descend to a 50x20 km orbit.

• Powered Descent Initiation (PDI), with a braking manoeuvre under inertial guidance, from an initial altitude of about 20 km.

• 'High gate', at about 1 km altitude, the point at which altitude and velocity information from the radar would start to be used for navigation updating (e.g. landing point may be changed on the basis of slope information from a three-beam radar altimeter). Further visual acquisition of the landing target is planned from here on.

• Hovering phase (max. 2 min) allows final verification of landing site from the ground (obstacle avoidance).