What kind of testing did we do for the first US spacewalk?

Question

In other words, how did we test out the environment outside the spacecraft before we had a spacewalk?

I guess no one knows.

Answer 1

The Mercury spacesuits were subjected to extreme heating and cooling both in air and in vacuum. I'm certain the Gemini suits (which were similar to the Mecury suits) were subjected to the same kinds of tests.

Instruments to monitor temperature, humidity, and air pressure were placed in the suits. While under normal pressure, they would be put into environmental chambers to heat and cool them. Then they would be put into vacuum chambers, heated, cooled, and leak checked.

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Answer 2

The space environemtn had been tested by unmanned satellites, dozens of them, long before the first spacewalk. It was because of those probes that the environment in space was understood enough that functional spacecraft could be designed and built for the Mercury and Vostok programs in the US and USSR.