Soft Landing

soft landing [′sȯft ′land·iŋ]

(aerospace engineering)

The act of landing on the surface of a planet or moon without damage to any portion of the vehicle or payload, except possibly the landing gear.

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Soft Landing 

of a space vehicle, a landing in which the velocity of the vehicle at the moment of contact with the surface of a planet or other celestial body is minimal (or in the ideal case, zero).

A soft landing is designed to ensure that the structure and systems of a vehicle will remain intact and that the vehicle will be able to continue functioning. The soft landing of winged vehicles (which have wing and body lift), for example, on planets with a sufficiently dense atmosphere necessitates gliding at low speeds and the ability to complete an airplane-type landing. In order to make a soft landing with space vehicles of axisymmetric shape (which have less lift), the vehicles must have deployable landing systems, such as a gliding parachute, paraglider, or rotor system (a type of helicopter rotors). In vehicles with a gliding parachute, additional devices, such as retrorockets, are installed to damp impact upon landing. The soft landing of a spaceship on celestial bodies that lack an atmosphere is accomplished by complete damping of the descent velocity by means of a retrorocket or special shock absorbers.

G. A. NAZAROV