Editing Surveyor program (section)

== Launch and lunar landing ==
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[[File:1965 Typical Atlas Centaur Stages.jpg|thumb|[[Atlas-Centaur]] injecting a Surveyor lander directly into trans-lunar flightpath]]
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&nbsp;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&nbsp;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&nbsp;km above the Moon, and then was jettisoned along with the radar unit at 11&nbsp;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 thruster|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&nbsp;m/s. The free-fall to the surface was in an attempt to avoid surface contamination by rocket blast.

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 {{convert|995.2|kg}} to {{convert|1040|kg}}, and their landing weights (minus fuel, jettisoned retrorocket, and radar unit) ranged from {{convert|294.3|kg}} to {{convert|306|kg}}.