Surveyor 5 - Mission

Mission

The mission experienced a helium leak in the system that pressurized the liquid-fuel vernier engines that could have resulted in failure. An improvised landing sequence which started the retrorocket just 42 km above the moon (about half the usual height) allowed vernier engines to bring the craft down in 106 seconds from a height of only 1340 m (about 10% of the usual). This brought the craft down with a helium pressure on the edge of what would have shut the engines down from lack of pressure.

The landing, however, was successful, and data was received for 2 weeks after the landing. A miniature chemical analysis lab using an alpha particle backscatter device was used to determine the lunar surface soil consisted of basaltic rock. A similar instrument, the APXS, was used onboard several Mars missions.

Surveyor 5 was the third spacecraft in the Surveyor series to achieve a successful lunar soft landing. The spacecraft had a basic triangular structure of aluminum tubing that provided mounting surfaces for engineering and scientific equipment. The objectives were to obtain postlanding television pictures of the lunar surface, conduct a Vernier engine erosion experiment, determine the relative abundance of the chemical elements in the lunar soil, obtain touchdown dynamics data, and obtain thermal and radar reflectivity data. Instrumentation for this spacecraft was similar to that of the previous Surveyors and included landing legs, a Vernier propulsion system, and numerous engineering sensors. An alpha-scattering instrument was installed in place of the surface sampler, and a small bar magnet attached to one footpad was included to detect the presence of magnetic material in the lunar soil. The spacecraft landed at 00:46:44 UT on September 11, 1967 (7:46 p.m. EST September 10) in Mare Tranquillitatis, at 1.41° N latitude and 23.18° E longitude (selenographic coordinates), within the rimless edge of a small crater on a slope of about 20 deg. The spacecraft transmitted excellent data for all experiments from shortly after touchdown until October 18, 1967, with an interval of no transmission from September 24 to October 15, 1967, during the first lunar night. Transmissions were received until November 1, 1967, when shutdown for the second lunar night occurred. Transmissions were resumed on the third and fourth lunar days, with the final transmission occurring on December 17, 1967. Pictures were transmitted during the first, second, and fourth lunar days.