As he exited the Apollo Lunar Module on July 20th of 1969, ready to set foot on the Moon, Neil Armstrong‘s immediate safety was in the hands of an incredible feat of engineering that is often overlooked: his A7L Spacesuit and backpack. Built at Lyndon B. Johnson Space Center by ILC Dover and Hamilton Standard, respectively, this early Extravehicular Mobility Unit (EMU) was required to provide, amongst other things, the following: a safe internal pressure; breathable oxygen; a regulated temperature; shielding from radiation; protection from micrometeorites, and a communications system. In addition, the suit’s eleven layers needed to provide ample levels of comfort and mobility so as to make it usable.

Below: a letter from Armstrong to the “EMU gang,” written in 1994 to mark the 25th anniversary of the Moon landing, in which he thanks them sincerely for their highly important work on what he calls his “spacecraft.”

Transcript follows.

(Source: Heritage Auctions; Image: Buzz Aldrin on the Moon, wearing the A7L Spacesuit, via.)

Transcript

NEIL A. ARMSTRONG

P.O. BOX 436

LEBANON, OH 45036 July 14, 1994 The EMU gang at

Johnson Space Center

Houston, TX 77058 To the EMU gang: I remember noting a quarter century or so ago that an emu was a 6 foot Australian flightless bird. I thought that got most of it right. It turned out to be one of the most widely photographed spacecraft in history. That was no doubt due to the fact that it was so photogenic. Equally responsible for its success was its characteristic of hiding from view its ugly occupant. Its true beauty, however, was that it worked. It was tough, reliable and almost cuddly. To all of you who made it all that it was, I send a quarter century’s worth of thanks and congratulations. Sincerely, (Signed) Neil A. Armstrong NAA:vw