Apollo 10 is considered to be full dress rehearsal for Apollo 11. Did the trial flight of Apollo 10 identify any improvements that were needed in the Saturn V, CSM and LM, to be done before Apollo 11 could lift off?

If yes, were they carried out?


2 Answers 2


The thrust deflectors on the descent stage were added to Eagle when it was already stacked on the Saturn V after the flights of Apollo 9 and 10 showed that the exhaust from the downward-facing attitude thrusters were impinging on the structure. Also, not really as a result of the test flights, the ground contact probe on Eagle's forward footpad was removed in case Armstrong tripped over it when he came down the ladder.

  • $\begingroup$ Worth mentioning, the positioning of these deflectors interfered with the LM radio communications, causing all kinds of headaches at the start of the landing sequence. $\endgroup$
    – Innovine
    Feb 20, 2021 at 22:54

The most familiar issue is that the Apollo 10 LM was still above its target weight by a couple of hundred pounds. A safe landing would have been physically possible, but not with the desired propellant margins. However, the lighter Apollo 11 LM had already been completed and delivered 4 months prior to the flight of Apollo 10 -- the production and assembly of the spacecraft was a deeply pipelined process -- so that wasn't an improvement identified or carried out after A10.

As with all the other flights in the Apollo program, a number of anomalies occurred, described in section 15 of the Apollo 10 Mission Report. Various corrective actions were taken to fix the anomalies -- mostly by making minor procedural changes. Skimming through those items, I don't see anything that would have been more than a minor inconvenience to the Apollo 11 mission.


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