Maximum span Antenna booms 5.6 m. (18 ft., 6 in.) Solar panels 3.7 m. (12 ft., 2 in.) Height 1.68 m. (5 ft., 6 in.) without panels Weight 385.6 kg. (850 lb.) Power Electrical; four solar panels with a total area of just over 4.8 sq. m. (58 sq. ft.) providing 375 w. to nickel-cadmium batteries Velocity control A 45.4 kg (100 lb.) thrust engine burning a system hydrazine mixture and nitrogen-tetroxide oxidizer Surveyor [Illustration: 43. Surveyor.] High-gain Antenna Omnidirectional Antenna A Thermally Controlled Compartment A Radar Altitude - Doppler Velocity Sensor Vernier Propellant Tanks Footpad 2 Crushable Block Attitude Control Gas Tank (Nitrogen) Solar Panel TV Camera Thermally Controlled Compartment B Alpha Scattering Instrument Electronics Canopus Star Sensor Omnidirectional Antenna B Footpad 3 Vernier Engine 3 Vernier Propellant Pressurizing Gas Tank (Helium) Alpha Scattering Instrument [Illustration: 44. _Apollo 12_ crewman examines _Surveyor 3_, which soft-landed on the Moon on April 19, 1967. The _Apollo 12_ (1969) Lunar Module is in the background.] The Surveyor Project, begun in 1960, consisted of seven unmanned spacecraft which were launched between May 30, 1966, and January 6, 1968. The craft were used to develop lunar soft-landing techniques, to survey potential Apollo landing sites, and to improve scientific understanding of the Moon. Five of the seven Surveyor spacecraft successfully landed on the Moon and performed their tasks well. They responded to 600,545 commands from Earth and returned 87,632 television images of their lunar surroundings. (_Surveyors 2_ and _4_ crashed into the Moon and were destroyed.) Besides returning TV images, _Surveyors 3_, _5_, _6_, and _7_ carried a soil-sampling claw which could dig a trench, and test soil hardness and other characteristics. The soil-sampler tests showed that the lunar surface would bear the weight of an Apollo Lunar Module. _Surveyors 5_, _6_, and _7_ carried instruments capable of making simple chemical analyses of the lunar soil near the spacecraft. This information told scientists that most lunar soil near the Surveyors was basalt, a common rock on Earth as well. The Surveyor spacecraft on exhibit, designated _S-10_, was used in ground-based tests of on-board equipment, and was not used on a mission. _S-10_ is exhibited as it would have appeared just before landing on the Moon. Prime contractor for the Surveyor spacecraft was the Hughes Aircraft Company. The project was managed by the National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. The spacecraft on exhibit is from the National Aeronautics and Space Administration.