Christoper Kraft cited two major reasons for the need for Apollo 10 to fly in
lunar orbit rather than landing:
- "To set timelines on activities up to and preparing for the landing. We
learned on the Apollo 9 LEM earth orbit flight that activities in space often
take longer than expected. We want to know how long it takes the astronauts
to do things, to check systems, to get ready to separate the LEM for the
descent to the moon.
- To better understand the navigation problem that exists around the moon.
By shaping the Apollo 10 mission to be identical to a moon landing down to
the point where you start powered descent, we'll be able to navigate exactly
as we will when we go for a landing."