Talk:Extra-vehicular activity
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Selected on Template:March 18 selected anniversaries (may be in HTML comment)
The article states that "The first EVA to perform an in-flight repair of the Space Shuttle was...". Does anyone know what was the first EVA to perform an in-flight repair (as opposed to EVA for the sake of it or EVA for installing additional equipment) ever, that sounds like an important milestone. Nikola 10:18, 30 December 2005 (UTC)
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[edit] Exhausting?
I've heard somewhere that EVA can be exhausting for astronauts to the point that they lose weight during one. Does that make any sense?
Exhausting? They usually stay out there for a good few hours! Just have a look at some of the more recent EVAs and their durations: http://en.wikipedia.org/wiki/List_of_spacewalks --UD75 21:26, 13 April 2006 (UTC)
Yes. It takes a lot of effort to deform the pressurized space suit. The astronaut's workload depends on how much the movements required bend the suit joints.
It's not as bad today as it was in the earliest days of space flight. On the first US EVA, Ed White saw his thermal glove float out of the Gemini capsule but he said he was just too tired to reach for it. On another Gemini mission, the EVA astronaut became so tired that he ended up clinging to the nose of the capsule until he had recovered enough to get back inside.
This problem is mitigated in four ways: (1) improved space suit design, (2) astronaut physique, (3) reduced pressure in the space suits, and (4) EVA task planning.
Space suit design has emphasized reducing the need to deform the shape of the suit. In the Shuttle suit, sliding joints at the shoulders were a major improvement in upper body mobility. The latest innovation in US space suits was the new gloves designed by Amy Ross (daughter of astronaut Jerry Ross) which were first flown on STS-88 (IIRC). All sorts of other ideas are being investigated including constant-volume joints and hard suits.
EVA crewmembers tend to be very muscular and they get really pumped up before a flight. The reason there have been very few female EVA astronauts is that in general female astronauts don't have the upper body strength required.
Reduced pressure obviously reduces the amount of force required to bend the suit. That's why astronauts are concerned about getting bent, hence the oxygen prebreathe protocol and apirin before every EVA.
In planning EVA tasks, engineers put a great deal of emphasis in keeping the astronaut's hands within the optimum work envelope (right in front of the astronaut's chest) and minimizing the need for repetitiously reaching long distances.
Greg 07:30, 31 August 2006 (UTC)
[edit] EVA collision hazards
An EVA is dangerous for a number of different reasons. The primary one is collision with space debris. Orbital velocity at 300 km above the Earth (typical for a Space Shuttle mission) is 7.7 km/s. This is 10 times the speed of a bullet, so the kinetic energy of a small particle with a mass 1/100th that of a bullet (e.g. a fleck of paint or a grain of sand) is equal to that of a bullet.
This statement may be correct for one object moving at 7.7 km/s relating to earth while the other collision object has no speed relating to earth. But for every other frame of reference this is wrong. Speeds and kinetic energies can be much higher or slower. --Abdull 14:32, 5 May 2006 (UTC)
I agree. We like to avoid EVA because it takes so much crew time. Orbital debris has not come up as a significant EVA hazard; the probability of a collision with an object as small as a space-suited astronaut is extremely low. Greg 10:44, 2 September 2006 (UTC)
I also agree. An astronaut on an EVA is also orbiting the Earth at 7.7 km/s, so the relative speed between him and the specks of dust is small. --141.154.234.142 08:57, 18 March 2007 (UTC)
[edit] strange sentence?
Still, some scientists are developing tele-operated robots for outside construction work, to potentially eliminate the need for human EVAs.
This sentence seems strange to me. Somehow the tone doesn't fit the article. I guess the "some" needs clarfiying, and probably a cite, but I was tempted to remove it completely as it didn't add anything to me. -21:04, 8 July 2006 (UTC)
[edit] Leonov picture
Is it a real photo ? I think there is no good photo from Leonov. Read here : http://starchild.gsfc.nasa.gov/docs/StarChild/space_level2/leonov_spacewalk.html Ericd 21:18, 20 July 2006 (UTC)
[edit] EVA Hazards: Glove Incident on STS-37
The document states: "One astronaut has suffered a spacesuit puncture. During STS-37, a small rod punctured the glove of one of the astronauts (the name is undisclosed, but it was either Jerry L. Ross or Jay Apt). However, the puncturing object, which stabbed the astronaut's hand as well, held in place, resulting in no detectable depressurization. In fact, the puncture was not noticed until after the spacewalkers were safely back inside Atlantis."
This paragraph has an external link to an essay by Geoff Landis that does not appear to be related to the incident.
The facts are a bit off, too. The astronaut's hand was not stabbed, and the puncture was not discovered until after Atlantis landed.
I see some difficulty with writing a Wikipedia article about it because no official public NASA documents give the details; hence, verification is available only via anecdotes from the people who were there. (That would be me. I worked on the STS-37 EVA. All the details came out during the EVA crew debrief at JSC after the flight.) Nevertheless, perhaps a wiser head can figure out how to tune up the article.
(See notes below.)
-- Greg 10:46, 2 September 2006 (UTC)
[edit] What really happened on STS-37
The EVA glove has a spring-steel palm restraint bar that keeps the palm from ballooning out away from the hand. Some time during the EVA, the palm restraint bar on the astonaut's glove was driven loose and punctured the pressure layer of his glove. The end of the palm restraint bar was still inside the outer layers of the glove.
We speculated that the glove failure occurred when the astronaut used his hand like a hammer to loosen a balky restraint pin on one of the CETA carts. There was a bit of consternation about that in the mission support room during the EVA.
The astronaut did not notice the problem at the time but when they got back inside he noticed that he had a blister between his thumb and forefinger. At that time, he thought it was because of chafing from the glove, which is common during an EVA, even more so before the new glove design.
After STS-37 landed, the space suits were sent to FEPAC for regular processing. A suit technician noticed a discoloration on the outside of the glove. It looked like rust. Analysis in the laboratory showed that the foreign material was the astronaut's blood.
They tore down the glove and discovered the problem with the palm restraint bar. In the subsequent investigation in the lab they discovered that the blood had coagulated and adhered to the steel restraint bar and the neopreme pressure layer, sealing the breach. The damage to the astronaut's hand was caused by having the skin between his thumb and forefinger exposed to vacuum, giving him the distinction of being only astronaut known to have bled into space.
If the astronaut's blood had not sealed the palm restraint bar in place, pressure probably would have driven it the rest of the way out. That would have left a 1/8" hole in the suit, a classic design case for space suits. In that case, we would have had a serious emergency. The astronaut's Secondary Oxygen Pack would have opened up to replenish the leakage, and he would have had 23 minutes to get back into pressure before suffering a high probability of neural damage. Of course, this did not happen; the breach was sealed and the astronaut was in no danger.
During informal discussions with the astronaut later (we are both science fiction buffs), we noted that such an incident had been foreshadowed by a science fiction story by Robert A. Heinlein entitled "Gentlemen, Be Seated." The difference was that, in Heinlein's story, the characters used their backsides to plug holes in a pressure shell on the moon. Greg 10:44, 2 September 2006 (UTC)
[edit] Spacewalks/EVA
I'm wondering how many europeans, except Thomas Reiter has performed EVAs? Or was Reiter the first one? --84.49.146.87 07:18, 14 December 2006 (UTC)
- Or are Russians not Europeans? Nikola 22:42, 18 March 2007 (UTC)
[edit] dubious commercial for some omega watch
"Included in this research was a wrist timepiece that would withstand the extremes of the outer space environment. After purchasing samples of the top branded chronographs (i.e. Rolex, Omega, Longines, etc.) and putting them through lab testing (including extreme cold/hot temperatures, humidity, G-forces, etc.), only the Omega Speedmaster model passed the NASA tests. It became the only approved watch for EVA during the Gemini project, was the first watch worn on the moon[1] and continues to be the only watch that may be worn during EVA."...which i removed. Quite a lot of stuff is worn by cosmonauts out of aircraft and there is no need to separately mention the wrist timepiece which was included except for commercial purposes.84.167.225.42 15:38, 18 January 2007 (UTC)
