Walter Holm BSGE 1958: Letter about the Lunar Excursion Module
The following is a handwritten letter sent to ISE.
Thought you might find this interesting:
There were tow vehicles involved in the moon- shot’s the Command module and the Lunar Excursion Module (LEM).
The Command Module would carry the LEM to the moon. The LEM would then land on the moon while the Command module orbited waiting for the LEM to return.
We had to be as certain as possible that the LEM would reignite on the moon and return to the Command module.
The vessel above was designed to give that assurance.
The LEM was placed inside the vessel. The cover was gasketed to make a vacuum-tight seal. The cover was placed on top using the 100-ton crane and bolted in place.
With the LEM inside, the vessel was evacuated by aspersion. The aspersion was accomplished by firing three Atlas rocket engines in parallel. The closest pressure we could get to the perfect vacuum of the moon was 110,000 ft.
The LEM was then commanded to ignite and it did. We had a reasonable expectation that LEM would return from the moon to the Command module. Fortunately it did.
This crude test in no way lessened the courage of the astronauts who pressed the “start” button on the moon’s surface vacuum.
Wally Holm, GE 58
Note: The propellants on LEM were AEROZINE 50 and Nitrogen tetroxide. These materials are hypergolic and explode on contact on earth.
But in a vacuum? Yes!