Launch and Lunar Landing
Each Surveyor mission consisted of a single unmanned spacecraft designed and built by Hughes Aircraft Company. The launch vehicle was the Atlas-Centaur which injected the craft directly into trans-lunar flightpath. The craft did not orbit the moon on reaching it, but directly decelerated from impact trajectory, from 2.6 km/s relative to the moon before firing retrorockets, to a soft landing about 3 minutes 10 seconds later.
Each craft was planned to slow to about 110 m/s (4% of speed before retrofire) by a main solid fuel retrorocket, which fired for 40 seconds starting at an altitude of 75.3 km above the Moon, and then was jettisoned along with radar unit, 11 km from the surface. The remainder of the trip to the surface, lasting about 2.5 minutes, was handled by smaller doppler radar units and three vernier engines running on liquid fuels fed to them using pressurized helium. (The successful flight profile of Surveyor 5 was given a somewhat shortened vernier flight sequence as a result of a helium leak). The last 3.4 meters to the surface was accomplished in free-fall from zero velocity at that height, after the vernier engines were turned off. This resulted in a landing speed of about 3 m/s.
Surveyor 1 required a total of about 63 hours (2.6 days) to reach the moon, and Surveyor 5 required 65 hours (2.7 days). The launch weights (at lunar injection) of the seven Surveyors ranged from 995.2 kilograms (2,194 lb) to 1,040 kilograms (2,300 lb), and their landing weights (minus fuel, jetisoned retrorocket, and radar unit) ranged from 294.3 kilograms (649 lb) to 306 kilograms (670 lb).
Read more about this topic: Surveyor Program
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