Surveyor 5 was similar to its predecessor, but the surface sampler from the earlier vehicle was replaced by an alpha-backscatter instrument to determine the relative abundance of the chemical elements in lunar material. In addition, a small bar magnet was installed on one of the lander’s footpads to indicate whether the lunar soil had magnetic properties.
Overcoming a near-fatal helium leak in a pressure regulator, engineers from JPL and Hughes Aircraft Company (the prime contractor for the spacecraft) expertly managed to safely land Surveyor 5 on the surface of the Moon in the southeastern region of Mare Tranquilitatis at 1.42 degrees north latitude and 23.20 degrees east longitude at 00:46:42 UT on Sept. 11, 1967.
The malfunction put the lander about 18 miles (29 kilometers) away from its target in an angular incline within the slope of a rimless crater.
Surveyor 5 was, however, the most successful of the series so far. The lander returned 18,006 photos before lunar night descended on Sept. 24, 1967. Controllers successfully commanded the vehicle to take another 1,000 photographs during the second lunar day between Oct. 15 and 24, 1967 and the fourth lunar day in December. In total, 20,018 pictures were transmitted.
In a new experiment, on Sept. 13, 1967, controllers fired the main engine for 0.55 seconds to examine the effects of disturbing the lunar surface. NASA announced that no new craters were created, nor was there any significant dust cloud due to the firing.
The alpha-scattering instrument had earlier been activated and found the soil to be composed of more than half oxygen with various amounts of silicon and aluminum.
Contact was lost with the lander on Dec. 16, 1967.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.