Q&A: EVAs with three or more crew?

[sdsds]

In 1992 the first three-person EVA took place during STS-49, to repair Intelsat 603. How many others have there been? Is ISS crew size and the preference for using a supporting IVA crew member the limiting factor?

[AmigaClone]

In 1992 the first three-person EVA took place during STS-49, to repair Intelsat 603. How many others have there been? Is ISS crew size and the preference for using a supporting IVA crew member the limiting factor?

That three person EVA on STS-49 was the only time three (or more) astronauts went outside their spacecraft at the same time.

I suspect that the ISS crew size and preference for having a supporting crew member might be just a couple of the factors that prevent the ISS from hosting an EVA with more than three people. The reason I suspect that is even when there was a crew of six on the ISS and the shuttle (with a crew of seven) was visiting there were no three or four person EVAs.

One big reason EVAs from the ISS are limited to two individuals is that there is no EVA task that would require three (or more) people outside.

[catdlr]

In 1992 the first three-person EVA took place during STS-49, to repair Intelsat 603. How many others have there been? Is ISS crew size and the preference for using a supporting IVA crew member the limiting factor?

That three person EVA on STS-49 was the only time three (or more) astronauts went outside their spacecraft at the same time.

I suspect that the ISS crew size and preference for having a supporting crew member might be just a couple of the factors that prevent the ISS from hosting an EVA with more than three people. The reason I suspect that is even when there was a crew of six on the ISS and the shuttle (with a crew of seven) was visiting there were no three or four person EVAs.

One big reason EVAs from the ISS are limited to two individuals is that there is no EVA task that would require three (or more) people outside.

The ISS US Air Lock and the suit-up room can only accommodate 2 US-based astronaut EMU's at one time.  If there were to be three or four EVA team, it would have to be two Russians using their airlock.

[Zed_Noir]

When ever the Polaris Dawn mission launches. That will be the opportunity for the first 4-person EVA, sort of. Since the Dragon interior will be depressurized, the crew of 4 have to suited up in full EVA regalia regardless of how many of them egress the Dragon. Maybe every crew member will get to go out, probably not at the same time.

[DaveJ576]

Following the Polaris Dawn example… Apollo 9. McDivitt, Scott, and Schweickart were all in EVA suits, with both the LM and CM depressurized. Technically, all three were “conducting an EVA”, but of course McDivitt never left the spacecraft. Extrapolating out, you would have to include Apollo 15, 16, and 17 as well.

[sdsds]

It is splitting hairs but if crew members who remain in a depressurized cabin are relying on umbilical connections for in-suit ECLS that doesn't seem like an EVA.

[saturnapollo]

Well, if you take the literal meaning of EVA - Extra Vehicular Activity, then it has to be outide the vehicle.

Keith

[Sam Ho]

It is splitting hairs but if crew members who remain in a depressurized cabin are relying on umbilical connections for in-suit ECLS that doesn't seem like an EVA.

That is more or less the difference between the U.S. and Russian EVA definitions.  From Walking to Olympus: An EVA Chronology (NASA SP-4507):

Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philosophies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress.

In this document, we apply the Russian definition to Russian EVAs, and the U.S. definition to U.S. EVAs. Thus, for example, Gemini 4 Command Pilot James McDivitt does not share the honor of being first American spacewalker with Ed White, even though he was suited and in vacuum when White stepped out into space.

https://www.nasa.gov/wp-content/uploads/2023/04/sp-4507.pdf

[AmigaClone]

Following the Polaris Dawn example… Apollo 9. McDivitt, Scott, and Schweickart were all in EVA suits, with both the LM and CM depressurized. Technically, all three were “conducting an EVA”, but of course McDivitt never left the spacecraft. Extrapolating out, you would have to include Apollo 15, 16, and 17 as well.

Skylab 2 (the first crewed mission to Skylab) also had a stand-up EVA with Weitz attempting to free the stuck solar panel while Conrad and Kerwin stayed inside their Apollo capsule.

[Nicolas PILLET]

We can also remember that there was a case with four people simultaneously on EVA, but from two different vehicles. It was on 16.09.1993 (Mir EO-13 and STS-51).

[duh]

Well, if you take the literal meaning of EVA - Extra Vehicular Activity, then it has to be outide the vehicle.

Keith

Somebody might demand that this be moved to the party thread, but if you were to someone who is a mathematician who specialized in topology, then the person who is still inside the spacecraft (by "our"
whoever "our" includes) definition would be outside the spacecraft by the topoogist's definition.  Ahh, once again logic falls apart or on its face (except for how to you fall when in space??).

[duh]

Well, if you take the literal meaning of EVA - Extra Vehicular Activity, then it has to be outide the vehicle.

Keith

Somebody might demand that this be moved to the party thread, but if you were to *talk to* someone who is a mathematician who specialized in topology, then the person who is still inside the spacecraft (by "our" whoever "our" includes) definition would be outside the spacecraft by the topoogist's definition.  Ahh, once again logic falls apart or on its face (except for how to you fall when in space??).

Edited the above to *talk to*  (asterisks to indicate location of edit)

[duh]

Well, if you take the literal meaning of EVA - Extra Vehicular Activity, then it has to be outide the vehicle.

Keith

Somebody might demand that this be moved to the party thread, but if you were to *talk to* someone who is a mathematician who specialized in topology, then the person who is still inside the spacecraft (by whoever "our" includes) definition would be outside the spacecraft by the topoogist's definition.  Ahh, once again logic falls apart or on its face (except for how to you fall when in space??).

Edited the above to *talk to*  (asterisks to indicate location of edit)
May have been tweaked with a second edit.

Having some time to reflect on this question, a thought did occur to me (Did I hear some say "amazing"?)

The people that stay inside the capsule or vehicle while using space suits might be called "space spelunkers" which leads to the interesting thought whether a space capsule opened to space could be considered a cave. Some of those that explore caves are refered to as spelunkers. Unfortunately, it appears that this definition does not fit since it seems that spelunkers are amateurs. However "space cavers" might be applicable.

However, wikipedia states "A cave or cavern is a natural void under the Earth's surface" which might be consider a show stopper. However the meanings of words change with the times, so it seems to me that that concern about a natural void can be ignored (IMO).

Continuing from https://en.wikipedia.org/wiki/Speleology

"Speleology is the science of exploration and study of all aspects of caves and the cave environment. Visiting or exploring caves for recreation may be called caving, potholing, or spelunking."

Therefore it seems reasonable (not necessarily correct) that a person who practices speleology should be called a "speleologist". The individuals are not up there for recreation as such, but are, it has been said repeatedly, doing science (although some might suggest it might be as much engineering as science for some portion of the activities). There are further nuances here that I will skip over at least for the time being, perhaps never to revisit.

From this it logically follows that, as far as I know, all space walkers that have left the vehicle are speleologists prior to leaving the capsule and immediately after re-entering the capsule at the end of the space walk. Meanwhile those in the capsule who are exposed to the space environment (vacuum and wearing space suits) are speleologists. This should make life "interesting" for those keeping the statistics about how many space walks there have been.

In summary, from my perspective, a spacewalker receives credit for two speleogy trips plus one space walk and those that remain in the capsule receive credit for one speleogy trip. Not to further confuse things, it might be best to count the total of the time outside the spacecraft plus the speleology time as the total spacewalk time.

In conclusion (thankfully, I heard some one say, and "about time" from another) Congratulations to
all Space Speleologists!!!!!!!!!!"