NASA Schedules Space Walks to Fix ISS Pumps; Orbital Sciences Launch Delayed

The ISS has been operating at partial capacity after a coolant pump malfunctioned last week. NASA has now announced the repair mission: "NASA currently plans for two Expedition 38 astronauts to venture outside the space station Dec. 21, 23, and 25. NASA astronauts Rick Mastracchio and Mike Hopkins will remove a pump module that has a failed valve. They will replace it with an existing spare that is stored on an external stowage platform. The pump is associated with one of the station's two external cooling loops, which circulate ammonia outside the station to keep both internal and external equipment cool. Each of the three spacewalks will begin at 7:10 a.m. and is scheduled to last six and a half hours. NASA TV coverage will begin at 6:15 a.m." NASA TV will be airing a preview of the space walks at 3 p.m. EST. As a result of the coolant pump malfunction and the repairs, NASA has also delayed the launch of Orbital Sciences' cargo resupply mission until at least mid-January.

AE-35 unit

[Anonymous Coward]

"Roger your plan to go EVA and replace Alpha-Echo three-five unit prior to failure."

Re:

[scuzzlebutt]

"Open the Pod Bay doors, HAL."

A question about space walks.

[Thanshin]

How dangerous is a space walk compared to, for example, a 100m depth scuba dive?

i.e.: If it wasn't so very expensive to send things up there, could space walking become a "leisure" activity?

Re:

[SuricouRaven]

How recreational is it? There's nothing to do - literally, nothing around you except the ship itsself. The equipment is cumbersome. I could see it working on the moon, possibly*, but not just in orbit. If you want to go floating free for fun, you'd be better off taking a huge inflatable structure of some sort so you can keep atmosphere in. Much more comfortable, and flexible enough for zero-g sports.

*There would, of course, be a golf course.

Re:

[Russ1642]

Well, the radiation is pretty harmful even if everything goes perfectly to plan, not that it's a whole lot worse than being inside the station.

Re:A question about space walks.

[Trepidity]

So far they seem to be one of the safer parts of spaceflight, in that there have been 204 spacewalkers [wikipedia.org], and none died or suffered serious injuries. Whereas a number of people have died during take-off or reentry. On the other hand, they're typically planned for very carefully and not done that often. And 204 is too small a sample to reliably compare it to the safety of scuba diving, since serious scuba accidents, especially by professionals, are far less common than 1/200 dives.

Re:

[Thanshin]

So, less dangerous than 250m scuba diving but probably more than 100m scuba diving.

So, no recreational even if it was cheap to send people up.

Re:

[gman003]

I think a better comparison is to ADS diving, in more ways than one.

Re:

[LifesABeach]

Other saying, "yes" to an invitation from NASA, other than that these folks are hard working and intelligent.

Re:

[cstacy]

http://www.ncbi.nlm.nih.gov/pubmed/9491253 [nih.gov] .... but that's even without a spacewalk.

Re:A question about space walks.

[tlhIngan]

How dangerous is a space walk compared to, for example, a 100m depth scuba dive?

i.e.: If it wasn't so very expensive to send things up there, could space walking become a "leisure" activity?

I think it's quite dangerous - for many reasons. Hence for planned missions, they train extensively in the Neutral Buoyancy Lab - spending months practicing doing some task that will take them a day in space.

They even train for non-routine servicing - while they don't train for the specific scenario, they train hard on how to get around the ISS and all that so everyone is familiar (none more so than the commander).

Effectively, a spacewalk ends up being "routine" because the astronauts spent months practicing until it became routine. It's why it took over a week for this spacewalk - they had to come up with the scenario and figure everything out so it ends up still being well choreographed.

In effect, it's "safe" purely because everyone's done it before. And there are well know abort procedures - if something happens, abort immediately and return back to station. No "give me one more second and I'll have it" sort of things - abort means abort and get your ass back to the airlock.

I'm sure that 100m scuba dive could achieve similar results, had everything been practiced for months ahead of time and failure modes explored and abort modes followed. Of course, it sort of ruins the whole spontaneity of the thing and a lot of the fun in doing it goes away. (Plus, they're trained astronauts, so they work as a team and consider that primary over self).

Re:A question about space walks.

[Jjeff1]

I read a lot about space, and am a scuba diver, here's my take.

First, diving to 100 meters is going to be fairly dangerous, certainly not something your typical sport diver would do. Beyond 100 feet, you'll increasingly have issues with nitrogen narcosis (you feel drunk), and you'll definitely be in the realm of exotic air mixes (helium instead of Nitrogen, less than surface amounts of O2, etc...). At 100m using normal air, your partial pressure (think concentration) of O2 is 180% of surface level (been a while since I had to do that sort of math), which would be poisonous. Lets just compare to 100 FEET of depth, which a sport diver might do. You could remain at that depth for 10-15 minutes without having to decompress. Stay longer, and you need to sit at depth (say 20 feet) for a while to let the air dissolved in your blood to slowly come out of solution. Go up too fast and it's like opening a bottle of pop, but in your blood. Those bubbles can get caught in your joints, or worse spine, and cause paralysis. Divers that DO engage in deep diving are doing technical diving. Most of the gear is the same as a sport diver, you just carry more of it, particularly tanks and regulators.

But space is worse. First, space suits don't run at normal air pressure, they're down around 4.3 PSI (normal earth is 15). The ISS runs at the same pressure as earth, so donning a space suit is the same as rising UP from depth while diving, you'd get the bends as soon as you open the hatch and exit the ISS (opening the pop bottle). To solve this, when doing an EVA, astronauts breathe 100% O2 for an hour before donning and exiting the ISS.

Second, you have all sorts of cooling issues in space. Your body gives off a lot of heat, and in space, there is no place for that heat to go, so the cooling systems are far more elaborate than any warming systems (often just a hose with hot water being piped down from the surface if you were commercial diving) you might use underwater.

Re:

[wiredlogic]

FWIW the Z-1 prototype suit [space.com] is designed to operate at 8.3 psi. Because the suit obviates an airlock, the ramp down and ramp up time needed to equalize pressure with a spacecraft can be incorporated into the spacewalk mission without having the astronaut sit around doing nothing.

Re:

[the_skywise]

DUDE!

Did you NOT see Gravity?!?!?
(Ok, sure - only the spacewalkers actually survived but that's not my point!)

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[account_deleted]

Comment removed based on user account deletion

Re:

[Russ1642]

You're kidding right? You spend a gazillion dollars sending them up there and they get a day off?

Re:Christmas

[jandrese]

I know you're joking, but time off is something NASA takes very seriously. It didn't used to be this way, they used to work Astronauts to the bone for exactly the reason you mentioned, but after a semi-revolt on one mission they changed the policy to insure that the astronauts get enough rest.

Re:

[Russ1642]

I absolutely wasn't joking.

Re:

[oodaloop]

Human beings need rest, at least if you want them functioning properly and making sound decisions.

Re:

[antdude]

Which space mission was that? I am curious to know more about it. Thank you in advance. :)

Re:

[Thor Ablestar]

I didn't hear about it but I believe it was just before Dennis Tito. The astronauts were so tired with computer problems with undocking MPLM that they even did not hold a meeting ceremony for cosmonauts arriving to the Station.

Re:

[MrLogic17]

Skylab 4 was the mission where te astraunuts revolted.

http://libcom.org/history/1973-skylab-4-mutiny [libcom.org]

Re:

[Thor Ablestar]

You're kidding right? You spend a gazillion dollars sending them up there and they get a day off?

Yes. We Russians are LAZY. And the first thing we do after entering our Salyut or Mir is to REST. We have no reason to speed up since there are 6 months before Soyuz warranty expires. The only big expenses are food, water and oxygen.

You Americans have a Shuttle that can be in orbit 2 weeks at most. And you do everything as troubled bees under strict supervision of Houston.

Re:

[Thor Ablestar]

They should better use some other coolant that is not as toxic as ammonia so heat exchangers are not needed. I propose propylenglycol or, better, Russian Vodka. Then, all the radiator panels outside would be fully passive and require no external pumps.

Pumps made by the lowest cost bidder

[perpenso]

This is *not* the first time they've had issues with one of these pumps. Apparently they are failing much faster than expected so the spares already in orbit are running very low.

Perhaps the Orbital Sciences launch is being delayed to add some additional pumps to its cargo.

I wonder what the problem is..

Pumps made by the lowest cost bidder? :-)

Re:

[sunking2]

The first was a mechanical pump failure. They stopped using it before it tore itself apart. In this case it's a valve that controls the ammonia flow into the boilers. Mechanically it seems fine. It's actually controlling just fine except that it believes the ammonia is offset by about 30 degrees. In other words, the current flow is what the flow should be if the ammonia were actually 30 degrees warmer or cooler (forget which) it is.

Unlike the previous failure with no shuttle it will never make it back to

Re:

[Bruce Perens]

They could put it on Dragon CRS 3.

Re:

[sunking2]

No, they can't. The dragon doesn't even come close to having the capacity needed to bring something like this down. I'm a fan of SpaceX but to think it's a drip in replacement for everything is naive.

Re:

[perpenso]

Also, isn't there a Canadian robot up there that is suppose to do this stuff?

It gets Christmas and Boxing Day off. :-)

Re:

[sunking2]

Someone who needs a mechanic to do a water pump should not be questioning the competence of those working in space.