- A hard landing is the deliberate destructive impact of a space vehicle on a predetermined
celestial target. Among the objectives of such a mission may be to test
propulsion and guidance or to take photographs of selected regions to
prepare the way for later soft landing
missions (as in the case of the Ranger probes); to create a seismic disturbance that can be registered by sensors
on the surface (as in the case of spent rocket stages and Lunar Module
ascent stages in the Apollo Project);
or to splash material from beneath the surface into space so that it
can be collected and/or analyzed by a mother craft (as in the case of Deep Impact).
- The term is also applied to an unintentional destructive impact of a spacecraft whose inbound
trajectory is incorrect or whose braking and/or landing mechanisms have
failed (as in the case of the Beagle 2 Mars lander).