Another STS-120 memory...looks more like 2 kids on Christmas morning…instead of the ‘master’ and the ‘rookie’ spacewalkers preparing to step out into the vacuum of space. Candid shot of me with my forever-hero and mentor Scott Parazynski, @SPOTScott, preparing for our ‘walk in the park’… :-P
Temperature swings during a spacewalk are eye-opening. The EMU suits do not have a ‘heater’. We wear liquid-cooled undergarments under the suit and you either have cooling, or no cooling. We do have glove heaters, that warm up the fingertips only, and if you get ‘behind the power curve’ with the glove heaters…you’re done until sunrise… :-(
Since, we’re orbiting at 17,500 miles/hour (28,000 kilometers/hour), roughly 5 miles/second (8 kilometers/second), we orbit the Earth once every 90 minutes…so every 45 minutes we have either a sunrise or sunset. In direct sunlight, temperatures can soar to 300-degrees Fahrenheit, and even close to 400-degrees Fahrenheit in the boundary layer close to reflective metallic surfaces. Then when the sun sets and we are in orbital eclipse, temperatures can plummet to 300-degrees below zero!
During the solar array repair EVA, we maneuvered the Space Station to an attitude that would provide maximum shielding of the array, and keep it in shadow as much as possible to minimize the amount of electrical current flowing into the mast. Normally this current is around 210 Amps…yes, you read that correctly, 210 Amps…soooo…needless to say, getting the suit electronics and metal tools within inches of the power strip on the array carrying this current…well…let me just use an old pilot phrase…”Pucker Factor” (PF)…let’s just say the PF-meter is pegged. :-)
Since I was stationed at the base of the solar array for about six hours during this EVA, in shadow…I couldn’t feel much of my body until I managed to crawl to a sliver of sunlight on the top of the mast canister to warm my hands. Incredibly interesting environment, and I am so thankful to our team that kept me alive to fight another day. Many thanks to Mojo and Dina for keeping me safe in the suit. A world of thanks to Derek as our fearless Flight Director.