Satellite Support of Apollo

In addition to the necessity of acquiring the skills necessary to maneuver in space prior to executing the Apollo mandate, NASA had to learn much more about the Moon itself to ensure that its astronauts would survive. They needed to know the composition and geography of Moon, and the nature of the lunar surface. Was it solid enough to support a lander, was it composed of dust that would swallow up the spacecraft? Would communications systems work on the Moon? Would other factors—geology, geography, radiation, etc.—affect the astronauts? To answer these questions three distinct satellite research programs emerged to study the Moon. The first of these was Project Ranger, which had actually been started in the 1950s, in response to Soviet lunar exploration, but had been a notable failure until the mid-1960s when three probes photographed the lunar surface before crashing into it.⁶⁵

The second project was the Lunar Orbiter, an effort approved in 1960 to place probes in orbit around the Moon. This project, originally not intended to support Apollo, was reconfigured in 1962 and 1963 to further the Kennedy mandate more specifically by mapping the surface. In addition to a powerful camera that could send photographs to Earth tracking stations, it carried three scientific experiments—selnodesy (the lunar equivalent of geodesy), meteoroid detection, and radiation measurement. While the returns from these instruments interested scientists in and of themselves, they were critical to Apollo. NASA launched five Lunar Orbiter satellites between 10 August 1966 and 1 August 1967, all successfully achieving their objectives. At the completion of the third mission, moreover, the Apollo planners announced that they had sufficient data to press on with an astronaut landing, and were able to use the last two missions for other activities.⁶⁶

Finally, in 1961 NASA created Project Surveyor to soft-land a satellite on the Moon. A small craft with tripod landing legs, it could take post-landing photographs and perform a variety of other measurements. Surveyor 1 landed on the Moon on 2 June 1966 and transmitted more than 10,000 high-quality photographs of the surface. Although the second mission crash landed, the next flight provided photographs, measurements of the composition and surface-bearing strength of the lunar crust, and readings on the thermal and radar reflectivity of the soil. Although Surveyor 4 failed, by the time of the program’s completion in 1968 the remaining three missions had yielded significant scientific data both for Apollo and for the broader lunar science community.⁶⁷