Robotic Lunar Precursors to Apollo

Abstract

In one four year period—1964 to 1968--humans learned far more about the Moon than had been learned before or since. This enormous increase in knowledge was driven by three series of small robotic spacecraft: Ranger, Surveyor and Lunar Orbiter. Some of these spacecraft had started their programmatic lives as remote laboratories, designed to do lunar science. All of them were later repurposed as precursors to the Apollo missions. That is, they were focused on gathering data needed to validate the engineering decisions needed for a successful lunar landing. This paper will focus on four questions. First, what did we know with any degree of certainty about the Moon prior to the first American robotic encounters in 1964? Second, what did we learn about the Moon as a result of Ranger, Orbiter and Surveyor series of spacecraft? Third, how well did that information guide the engineering decisions made for the Apollo landings of humans on the Moon? Fourth, what does this tell us about how NASA might today garner the information needed to guide engineering decisions in America’s return to the Moon?