Wednesday, March 18, 2015

50th Anniversary of the first Space Extravehicular Activity

Even though Soviet era Lt. Col. Alexey Leonov did his first 10-minute extravehicular activity – or EVA – back in March 18, 1965, why is it that Hollywood still haven’t managed to portray a scientifically-accurate one in movies?

By: Ringo Bones

Ever wondered why Hollywood movies still haven’t managed to portray a scientifically-accurate portrayal of an extravehicular activity or spacewalk – i.e. movies like Clint Eastwood’s Space Cowboys and the recent one that stars Sandra Bullock titled Gravity – even when it is already 50 years after Soviet era cosmonaut Lt. Col. Alexey Leonov did a 10-minute long EVA back in March 18, 1965 and Major Edward White did a 20-minutte long EVA back in July 3, 1965? Is it all due to a lack of scientifically-accurate information of the subject?

All extravehicular activity in space using current spacesuits available to us today requires a lengthy pre-breathing of pure oxygen at reduced pressures, tragically, due to the Apollo I fire that happened back in April 24, 1967 that killed Major Ed White, Gus Grissom and Roger Chaffee. Prior to the Apollo I fire, NASA astronauts breathe – i.e. use – oxygen in their cabin that is at the same atmospheric pressure as their spacesuits – i.e. 29-percent of the atmospheric pressure at sea level or 4.3 pounds per square inch. This is the reason why Ed White more or less donned his spacesuit within 3 minutes or so before stepping out of his capsule – instead of a 40 minute to 4-hour pre-breathing pure oxygen at 4.3 pounds per square inch before stepping out in a spacesuit into the vacuum of space – like astronauts had done when they change spacecraft “atmospheres” to an oxygen-nitrogen mix at 11.3 pounds per square inch – equivalent to about the prevailing atmospheric pressure 7,000 feet above sea level or about 75-percent less than the 14.7 psi sea level atmospheric pressure - and the same system used in commercial passenger jets.

Blame it on the quirk of human physiology that NASA astronauts have to pre-breathe pure oxygen at 4.3 psi for 40 minutes to 4 hours depending on the duration of the EVA. If not, they would suffer the bends – i.e. formation of painful nitrogen bubbles in their blood vessels and joints. A lengthy pre-breathing scene is something not even portrayed in Space Cowboys and the movie Gravity – even just a truncated 30 to 90 second scene for semblance of “scientific authenticity”. It would have been a great opportunity to insert a Hamlet-like soliloquy in these scenes before they don their Hamilton Standard life support backpacks to their 15-million US dollar spacesuits as they ready to step out into the great void. Lt. Col.  Alexey Leonov’s and Major Ed White’s trailblazing EVA’s are still a stuff of legend indeed 50 years on.       


Madison Scott said...

I still admit that Lt. Col. Alexey Leonov stepping out of his Voshkod II capsule for the world's first EVA back in March 18, 1965 is still one of mankind's "giant leaps" in the field of space exploration and so does Major Ed White's 20-minute EVA out of his Gemini 4 capsule- twice as long as Soviet era cosmonaut Lt. Col. Leonov's. The primary purpose of pre-breathing pure oxygen is to purge excess nitrogen bubbles out of the astronauts bloodstream to avoid the bends when donning current NASA spacesuits that has a "reduced atmospheric pressure of pure oxygen minimally required to protect a human being from the hard vacuum of space". But why NASA's mandatory up to 4-hours pre-breathing given that the Space Shuttle's internal atmospheric pressure is already equivalent to 7,000 feet of Earths atmospheric pressure with oxygen-nitrogen mix? I have an elderly uncle who used to be employed by the US Air Force to do reconnaissance overflights via the U-2 Spyplane and while wearing the 1950s era Cold-War Dave Clark partial-pressure suits which have a pressurization of only about 2.7 psi, he only required 3-hours of pre-breathing pure oxygen from a USAF air base that's no more than a few hundred feet above sea level on missions that almost lasted 48 hours before breathing again normal sea-level pressure oxygen-nitrogen of the Earth's atmosphere.

April Rain said...

Most working astronauts on the International Space Station now follow the pre-breathe protocol due - as you've factually cited in your blog - the ISS cabin is a oxygen-nitrogen atmosphere equivalent to 7,000 feet while the current issue EVA spacesuits has an equivalent internal atmospheric pressure similar to that at 38,000 feet due to joint flexibility reasons - though it is of pure oxygen at a little over 4 psi. The current pre-breathe protocol can be shortened to 2-hours 20-minutes via performing strenuous exercises using the stationary bikes / exercise bikes on the ISS as the astronauts pre-breathes pure oxygen to purge excess nitrogen out of their bloodstream as they move to the lower pressured areas of the ISS to prepare donning the EVA suits.