Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump 90
The ISS crew can breathe a little easier now; the NY Times reports that the ammonia pump repair that the station has needed has now been partly completed, and in less time than expected. More work is scheduled, but, says The Times:
"The astronauts, Col. Michael S. Hopkins of the Air Force and Richard A. Mastracchio, were far ahead of schedule throughout the spacewalk as they detached tubing and electrical connectors from the pump. They were able to remove the 780-pound module and move it to a temporary storage location, a task that had been scheduled for a second spacewalk on Monday. ... Colonel Hopkins and Mr. Mastracchio stepped out of an airlock at 7:01 a.m. Eastern time, and even though they accomplished more than they had set out to do, they were able to return at 12:29 p.m., an hour earlier than had been scheduled. The two encountered few complications."
Ars Technica has video, too.
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And... /. ate my </troll> bugger. Well, here it is.
Overly optimistic (Score:5, Funny)
As everyone knows, all projects involve several trips to Home Depot for the odd tool or bolt that was overlooked in the initial planning stage.
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As everyone knows, all projects involve several trips to Home Depot for the odd tool or bolt that was overlooked in the initial planning stage.
That's what made this newsworthy.
Of course, they said "few" problems. I'm wondering if one of those problems was ending up with extra bolts at the end that don't match up to any of the empty spots....
Re:Overly optimistic (Score:4, Funny)
I'm wondering if one of those problems was ending up with extra bolts at the end that don't match up to any of the empty spots....
I used to do this as a kid with old typewriters dad would bring home for me to take apart and put back together. There would usually be parts left over at the end but because everything still worked dad said I had made the machines "more efficient."
And yea, the lack of interest in space even amongst the geek community is appalling.
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I used to do this as a kid with old typewriters dad would bring home for me to take apart and put back together. There would usually be parts left over at the end but because everything still worked dad said I had made the machines "more efficient."
I used to do this when I was racing motorcycles. It was called 'adding lightness'.
"What're you bringing the rope for?" (Score:2)
Our motto is:
"The only way we'll need that is if we don't bring it."
Excuse the pedantry... (Score:1)
I know it's a nitpick, but isn't 7:01 a.m. - 12:29 p.m. more like 5.5 hours? I understand that they were an hour faster than planned (meaning they planned 6.5 hours) but the title seems a bit off nonetheless...
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What counts as the start and end point of an EVA varies depending on what Agency is reporting it and who wrote the press release. The start can be anything from the start of decompression, reaching vacuum, opening the hatch or stepping outside, and the end stepping back in, closing the hatch, starting recompression or returning to atmospheric pressure in the airlock. In this case it's 5.5 hours outside, but there will have been more time spent inside but in vacuum at the start checking the suits are working
Re:Excuse the pedantry... (Score:5, Funny)
I know it's a nitpick, but isn't 7:01 a.m. - 12:29 p.m. more like 5.5 hours? I understand that they were an hour faster than planned (meaning they planned 6.5 hours) but the title seems a bit off nonetheless...
Considering the ISS orbits the earth about every 90 minutes, it was more like 3 days and an hour.
Nickpick +5
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Rookie mistake. You forgot to allow for daylight savings time.
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....while in orbit, where they don't feel the effects of gravity?
They feel the effects of gravity, just not as much gravitational pull from the Earth. Oh, and they still feel the effects of mass -- equal and opposite reaction and all that. Basically means that they were unable to rely on gravitational pull or friction to move the module. Sounds tricky, and not something I'd want to try (in space, 780 pounds will 'fall' whichever direction it is moving, even if you're in the way).
If you were wondering how it could be 780 pounds, I presume that was measured at sea level
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They feel the effects of gravity
No they don't.
Gravity is certainly there, keeping the ISS in orbit (as opposed to it shooting off into space in a straight trajectory), but as the astronauts are constantly 'falling' they don't feel the effect of it. This is why there's no up or down, why their bones atrophy and why they feel nauseous when they first arrive.
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They feel the effects of gravity
No they don't.
Gravity is certainly there, keeping the ISS in orbit (as opposed to it shooting off into space in a straight trajectory), but as the astronauts are constantly 'falling' they don't feel the effect of it. This is why there's no up or down, why their bones atrophy and why they feel nauseous when they first arrive.
Yes they do; they just don't feel the SAME effects. But they're still gravitationally attracted to the module and vice versa.
Unless you're specifically talking about the fact that they don't feel the same gravitational effects they feel when on earth, in which case you're completely correct. It's much more subtle.
You can't feel gravity (Score:2)
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Adespoton is spot on. No gravitational force can be detected
If no gravitational force can be detected, then how can they 'feel' the effects of gravity? This is completely contradictory.
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Adespoton is spot on. No gravitational force can be detected
If no gravitational force can be detected, then how can they 'feel' the effects of gravity? This is completely contradictory.
They "feel" the effects of gravity by the massive object(s) they're interacting with being in a frictionless environment and not behaving how their brains tell them they should. Gravitational micro effects might not be much here on earth, where we have a buffer of matter, but when the only objects are the ones you're directly interacting with, there's nothing to interfere with the very small gravitational forces involved.
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So subtle, in fact, that they don't feel it at all.
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But they're still gravitationally attracted to the module and vice versa.... It's much more subtle.
Yeah, about as subtle as the tidal forces I feel when the moon is overhead. No, actually, a quick back-of-envelope calculation shows it is infinitesimally smaller than that.
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First, the pound is a unit of mass as well as a unit of force, thanks to our archaic English unit system. You can keep them apart by using pounds-force (lbf) and pounds-mass (lbm).
Second, the effect of gravity at the height of the ISS is about 88% of what it is at sea level. If it has a mass of 780 lbm, the gravitational force on it will be 689 lbf.
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Stick to metric, it is much easier, a Kilogram is a unit of mass, and a Newton is a unit of force.
F = Ma
g = about 9.8 m/s^2
so if gravity is 88% of Earth sea level, then the force on a 1Kg mass is equal to 1 * 9.8 * 0.88 Newtons, which is about 8.6 Newtons. The imperial system is way to complicated to be useful!
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...which is why I used the word "archaic". Yes, kg and newtons are much better units, although there are those who try to corrupt the setup by defining a "kilogram-force" as the weight of one kg.
Incidentally, all the Imperial units are now formally defined in terms of SI units; the pound-mass is defined as 0.45359237 kg. The kilogram is also the only SI unit still based on an actual physical object; there's a platinum cylinder in a vault outside Paris that by definition masses one kg. And even that is on
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yes "kilogram-force" is ugh!
Many years ago in NZ there where some US warplanes, and I saw the abomination 'Kg/cm^2" (the 2 was actually a superscript) - arghhhh!
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also when NZ went metric, and at least a couple of years AFTER the inch was legally define as 25.4mm, cardboard converters were given out stating that an inch = 25.3999997 mm (don't remember the exact number of 9's!)!!!!!
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pound is force to everyone who understands and uses it regularly. pounds is only mass to idiots on wikipedia with no idea what they're on about
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First, the pound is a unit of mass as well as a unit of force, thanks to our archaic English unit system. You can keep them apart by using pounds-force (lbf) and pounds-mass (lbm).
No it isn't. A pound is a unit of force only. Our archaic English unit system uses the slug as a unit of mass.
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http://www.engineeringtoolbox.com/mass-weight-d_589.html [engineeringtoolbox.com]
"The English Engineering System - EE
In the English Engineering system of units the primary dimensions are force, mass, length, time and temperature. The units for force and mass are defined independently
the basic unit of mass is pound-mass (lbm)
the unit of force is the pound (lb) alternatively pound-force (lbf).
In the EE system 1 lb of force will give a mass of 1 lbm a standard acceleration of 3
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Re:780-pound module.... (Score:4, Informative)
....while in orbit, where they don't feel the effects of gravity?
They don't feel the effects of gravity, but they very much feel the effects of inertia.
In this context (i.e., earth orbit) the 780 lbs of the module refers to mass rather than weight. If the module were drifting and they had to stop it by grabbing it while they were connected to the ISS, you can bet they'd feel the effects of inertia. For the two-dimensional analogy, imagine a refrigerator, sliding on a perfectly slippery ice rink.
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Very definitely they are affected by gravity, or they would not stay in orbit but go off independently of Earth!
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Very definitely they are affected by gravity, or they would not stay in orbit but go off independently of Earth!
Correct, but the point is that they don't feel the effect of gravity because they are in a constant state of free-fall. The orbital motion keeps them from hitting the earth while they're in that state.
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There is still the tidal effect.
If you have a non-conducting rod in orbit, it will try and align itself pointing towards the Earth's gravitational centre - so long as other forces do not prevent that.
But the key thing is, is not to propagate the myth that gravity does not apply in orbit - I know what _YOU_ mean (but, did you forget the tidal effect still applies?), but lay people will tend to take what you say at face value, hence my strenuous objection!
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There is still the tidal effect.
If you have a non-conducting rod in orbit, it will try and align itself pointing towards the Earth's gravitational centre - so long as other forces do not prevent that.
Yes, correct again. However, the tidal effect takes a long time to synchronize an earth-orbiting object's rotation to the earth. I'm not up on the numbers, but surely it is much longer than a typical space mission -- perhaps even longer than humanity has been in space? I invite correction from those who know better.
In any case, the astronauts still would not feel tidal effects because they are too small. But if they were in orbit around an object with a very strong gravitational field, then they certain
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Using the tidal force was an idea for stabilizing satellites I read about 45 years ago. I don't recall the time periods, but I suspect that it would be significantly less than a year. The longer the 'rod' the more pronounced the effect.
I suspect that they found using gyroscopes gave faster stabilization and a lot more control, while have a 'keel' would have a higher mass penalty and be far less effective than using gyroscopes!
I smell (Score:2)
I smell a conspiracy. No WAY government workers finish ahead of schedule, unless it's for breaks, lunch or end of day.
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And a private company feeding off US taxpayer dollars finishing early? Where's the profit in that?
Happens all the time. Usually when the contract has bonuses for early completion, or it was a fixed-price contract. Sometimes you'll have a contracter overestimate the labor involved, because the task was poorly defined and the contractor made sure they'd still make a profit when the task turns out to be harder than originally thought. Pretty common in R&D contracts.
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Sometimes you'll have a contracter overestimate the labor involved, because the task was poorly defined and the contractor made sure they'd still make a profit when the task turns out to be harder than originally thought. Pretty common in R&D contracts.
Contractors who estimate a job to go perfectly have skinny children.
And a private company feeding off US taxpayer dollars finishing early? Where's the profit in that?
Bid job.
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Naw, man, that's the Depends that you smell. And no shower on the other end - talk about a motivator.
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Naw, man, that's the Depends that you smell. And no shower on the other end - talk about a motivator.
That's not even the worst of it. From the article:
The astronauts also had improvised snorkels made out of plastic tubing and Velcro, extending from their helmets down into the chest area of the spacesuit. If water encroached, the tube would allow them to breathe air from the lower part of the suit.
"Dutch oven" doesn't even begin to cover it.
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No WAY government workers finish ahead of schedule, unless it's for breaks, lunch or end of day
...or spending tax payer money!
Re:Seeing the gravity is only 1/6th up there (Score:4, Informative)
This is low earth orbit, not the moon.
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Yeah it is surprising how many people think there is no gravity in orbit.
Gravity is only reduced by roughly 10 percent at that distance from earth. The reason it seems like there is no gravity is you are always falling towards the earth. You just happen to keep missing !
Do a retrograde burn and you will stop missing quickly though.
Better headline (Score:2)
"ISS crew breathing easier with Ammonia freely flowing".
Well, funnier anyway.
Why not just push the old one down to Earth (Score:2)
Why store it? Why not just give it a good push away from the station earthwards?
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Failure analysis. Didn't you see '2001'?
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Plus something that's mostly metal, fairly solidly built, and masses 390 kilos is not going to burn up completely on its way to the ground. Even though it will almost certainly not hit anyone the bad press is something that NASA still has to worry about.
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mostly metal, fairly solidly built
most space junk is built from extremely lightweight materials like aluminium/titanium alloys or carbon/glass fibre reinforced composites, and whilst they are strong and rigid they aren't necessarily solid or robust. apart from hoping the launch vehicle doesn't blow up, during most satellite launches the design engineers are crossing their fingers and praying that their multi-million dollar piece of equipment doesn't vibrate to bits.
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True enough, but it's an ammonia refrigeration unit, there's only so much lightening that you can do to something like that.
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Yeah... (Score:1)
"Ammonia".... Howard f-ed up the space-loo again...
Bravo (Score:1)
Smooth spacewwalk (Score:3)
If you're walking in space and its bumpy then you have a big problem
Human achievement (Score:3)
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The space station travels at roughly 17,500 MPH.
Everything in the cosmos is traveling at roughly 17,500 MPH if you pick the right point of reference for each body.
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But you have a good point. Who can say where in space something is moving zero MPH. Still, I say that these astronauts do things that aren't looked at as astonishing, but should be.
I'm curious... (Score:1)
Re:I'm curious... (Score:5, Informative)
The heat sink in your computer would be pretty miserable at dumping waste heat into space. Terrestrial heat sinks typically heat into a fluid, such as the air that your computer's fans blow across the heat sink.
Problem: there is no air (or anything else into which heat may be transferred) in space. Radiative cooling - that is to say, releasing infrared radiation - does occur, but it is *far* slower that conductive cooling. To do that effectively, though, you want a big, hot surface area that is shadowed from all other heat sources in the region (that big fusion reactor the Earth orbits counts as "in the region" here).
To cool an artificial satellite effectively, especially a big one like ISS, you use a heat transfer system (in this case, they apparently use ammonia) to concentrate the heat into radiative cooling surfaces on the shadowed side of the station. This system definitely adds complexity, not to mention generating a bit of heat itself(entropy always increases), but without it, the side of the station facing the sun would cook, and the shadowed side wouldn't get hot enough for effective radiative cooling.
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In fairness, the radiator fins used on spacecraft are kind of like a terrestrial heat sink. There's no fans or anything like them, of course, but the basic concept of moving heat from the part that doesn't want to get too toasty to the part that is designed to accept all that heat and release it into the environment is much the same. The ammonia refrigeration system is required to achieve the actual moving and concentrating of the heat in the radiators, and (unlike the heat sink on a CPU) those radiators wi
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There is nothing in the vacuum..so there is a specific heat of roughly 0.
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Also you can't blow it out...because there isn't air.
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Pounds are a unit of weight
There is also a unit of mass called the pound.
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This is a US based website. People in the US understand pounds of weight. They typically do not understand kilograms, and definitely do not understand slugs, of mass. Using pounds is the most sensible way to report it.
In reference to the Earth at that altitude, it weighs around 700lbs. Space is not a "weightless environment". You cannot make such statements without specifying first that you're operating off the local space station reference frame.
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Using pounds is the most sensible way to report it.
It may be the best way for the average American understand it, but that doesn't make it sensible.
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I never suggested using pounds as a unit of mass.
Using pounds (weight) as a measurement of something in a weightless environment makes just as little sense.
It would weigh that much if it wasn't in orbit, but it is, so it doesn't.
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I never suggested using pounds as a unit of mass.
http://slashdot.org/comments.pl?sid=4585781&cid=45765969 [slashdot.org]
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I never suggested using pounds as a unit of mass.