Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump

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Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump

Posted by timothy on Saturday December 21, 2013 @08:24AM from the easy-peasy-space-is-breezy dept.

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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Overly optimistic by PPH · 2013-12-21 08:38 · Score: 4, 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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Have gnu, will travel.
1. Re:Overly optimistic by Em+Adespoton · 2013-12-21 08:56 · Score: 1
  
  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....
2. Re:Overly optimistic by nickserv · 2013-12-21 09:09 · Score: 3, 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.
  
  --
  Less *is* more.
3. Re:Overly optimistic by ColdWetDog · 2013-12-21 09:24 · Score: 1, Funny
  
  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'.
  
  --
  Faster! Faster! Faster would be better!
4. Re:Overly optimistic by Anonymous Coward · 2013-12-21 15:02 · Score: 0
  
  Yeah, I know about that. Both from living with a Home Depot nearby and by working in remote locations. No matter how much you plan before heading out into the middle of no where, you'll still have surprises and you'll still have to make do. Over time people start asking, "Why are you bringing that?" Then one day they learn why.
Excuse the pedantry... by Anonymous Coward · 2013-12-21 08:39 · 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...
1. Re:Excuse the pedantry... by Vulch · 2013-12-21 10:33 · Score: 2
  
  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 properly (especially after the water leak last time) and at the end making sure there's no ammonia been brought back inside.
2. Re:Excuse the pedantry... by PNutts · 2013-12-21 10:45 · Score: 4, 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
3. Re:Excuse the pedantry... by quenda · 2013-12-21 23:14 · Score: 1
  
  Rookie mistake. You forgot to allow for daylight savings time.
WOW! by Anonymous Coward · 2013-12-21 08:47 · Score: 0

ï
780-pound module.... by Anonymous Coward · 2013-12-21 08:52 · Score: 0

....while in orbit, where they don't feel the effects of gravity?
1. Re:780-pound module.... by Em+Adespoton · 2013-12-21 09:00 · Score: 1
  
  ....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 at STP, and doesn't refer to how much it cost to build.
2. Re:780-pound module.... by Deadstick · 2013-12-21 09:24 · Score: 2
  
  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.
3. Re:780-pound module.... by Anonymous Coward · 2013-12-21 09:25 · Score: 0
  
  It's always 780 pounds. lbs is a unit of mass, not weight.
4. Re:780-pound module.... by Anonymous Coward · 2013-12-21 09:56 · Score: 0
  
  Oh, gravity is there. Not as strong as on ground level, but still there. But since they're continually falling and missing the ground because of their speed, it kinda looks like there's no gravitational pull - but if there wasn't, they would continue straight ahead out into space on a tangent to their current orbit.
5. Re:780-pound module.... by CohibaVancouver · 2013-12-21 10:18 · Score: 1
  
  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.
6. Re:780-pound module.... by Em+Adespoton · 2013-12-21 11:07 · Score: 1
  
  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.
7. Re: 780-pound module.... by Anonymous Coward · 2013-12-21 14:43 · Score: 0
  
  Lbs is unit of weight. Slugs is the unit of mass.
8. Re:780-pound module.... by ClickOnThis · 2013-12-21 14:55 · Score: 3, 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.
  
  --
  If it weren't for deadlines, nothing would be late.
9. Re:780-pound module.... by sjames · 2013-12-21 16:35 · Score: 1
  
  So subtle, in fact, that they don't feel it at all.
10. Re:780-pound module.... by Nivag064 · 2013-12-21 18:26 · Score: 1
  
  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!
11. Re:780-pound module.... by Nivag064 · 2013-12-21 18:27 · Score: 1
  
  Very definitely they are affected by gravity, or they would not stay in orbit but go off independently of Earth!
12. Re:780-pound module.... by crutchy · 2013-12-21 21:54 · Score: 1
  
  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
13. Re:780-pound module.... by quenda · 2013-12-21 23:18 · Score: 1
  
  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.
14. Re:780-pound module.... by Deadstick · 2013-12-22 04:40 · Score: 1
  
  ...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 the way out...within a few years the kilogram will be based on the Planck constant.
15. Re:780-pound module.... by wagnerrp · 2013-12-22 05:34 · Score: 1
  
  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.
16. Re:780-pound module.... by Nivag064 · 2013-12-22 06:30 · Score: 1
  
  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!
17. Re:780-pound module.... by Nivag064 · 2013-12-22 06:33 · Score: 1
  
  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!)!!!!!
18. Re:780-pound module.... by Deadstick · 2013-12-22 07:21 · Score: 1
  
  http://www.engineeringtoolbox.com/mass-weight-d_589.html
  "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 32.17405 ft/s^2."
19. Re:780-pound module.... by ClickOnThis · 2013-12-22 08:22 · Score: 1
  
  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.
  
  --
  If it weren't for deadlines, nothing would be late.
20. Re:780-pound module.... by wagnerrp · 2013-12-22 08:41 · Score: 1
  
  And yet, no self respecting engineer would use the pound-mass measure, as it complicates any calculations in the system by requiring the addition of a unitless gravitational constant term.
21. Re:780-pound module.... by Nivag064 · 2013-12-22 09:18 · Score: 1
  
  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!
22. Re:780-pound module.... by ClickOnThis · 2013-12-22 10:45 · Score: 1
  
  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 certainly would feel something unpleasant.
  
  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!
  The OP began a discussion about what the astronauts feel, and I was sticking to that topic. But thanks for the clarifications. I agree that one should disabuse lay people from the false notion that there is "no gravity" in earth orbit.
  
  --
  If it weren't for deadlines, nothing would be late.
23. Re:780-pound module.... by Nivag064 · 2013-12-22 11:30 · Score: 1
  
  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!
24. Re:780-pound module.... by Anonymous Coward · 2013-12-23 00:48 · Score: 0
  
  The longer the 'rod' the more pronounced the effect.
  That's what your mom said.
I smell by JustOK · 2013-12-21 08:55 · Score: 1

I smell a conspiracy. No WAY government workers finish ahead of schedule, unless it's for breaks, lunch or end of day.

--
rewriting history since 2109
1. Re:I smell by Anonymous Coward · 2013-12-21 09:08 · Score: 0
  
  And a private company feeding off US taxpayer dollars finishing early? Where's the profit in that?
2. Re:I smell by bill_mcgonigle · 2013-12-21 09:36 · Score: 1
  
  Naw, man, that's the Depends that you smell. And no shower on the other end - talk about a motivator.
  
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  My God, it's Full of Source!
  OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
3. Re:I smell by fluffy99 · 2013-12-21 10:14 · Score: 1
  
  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.
4. Re:I smell by Jeremi · 2013-12-21 16:25 · Score: 1
  
  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.
  
  --
  
  I don't care if it's 90,000 hectares. That lake was not my doing.
5. Re:I smell by crutchy · 2013-12-21 21:55 · Score: 1
  
  No WAY government workers finish ahead of schedule, unless it's for breaks, lunch or end of day
  ...or spending tax payer money!
6. Re:I smell by rmdingler · 2013-12-22 01:10 · Score: 1
  
  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.
  
  --
  Happiness in intelligent people is the rarest thing I know.
  Ernest Hemingway
Re:Die... by magic+maverick+ · 2013-12-21 09:05 · Score: 0

And... /. ate my </troll> bugger. Well, here it is.

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Re:Die... by Anonymous Coward · 2013-12-21 09:06 · Score: 0

We believe you...
Seeing the gravity is only 1/6th up there by Anonymous Coward · 2013-12-21 09:10 · Score: 0

800 pound gorillas only weight 100 pounds at most.
1. Re:Seeing the gravity is only 1/6th up there by Deadstick · 2013-12-21 09:26 · Score: 3, Informative
  
  This is low earth orbit, not the moon.
2. Re:Seeing the gravity is only 1/6th up there by anethema · 2013-12-21 18:46 · Score: 1
  
  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.
  
  --
  
  It's easier to fight for one's principles than to live up to them.
It ain't heavy it's my ammonia pump by Anonymous Coward · 2013-12-21 09:13 · Score: 0

"...remove the 780-pound module"
Surely that took more than 2 men to handle./
Better headline by SuperKendall · 2013-12-21 09:17 · Score: 1

"ISS crew breathing easier with Ammonia freely flowing".
Well, funnier anyway.

--
"There is more worth loving than we have strength to love." - Brian Jay Stanley
5.5 hours, not 6.5 hours by Anonymous Coward · 2013-12-21 09:20 · Score: 0

Unless they passed close to a black hole whilst carrying out the procedure, 7:01am to 12:29pm is 5.5 hours, not 6.5 hours
Why not just push the old one down to Earth by Gothmolly · 2013-12-21 09:21 · Score: 1

Why store it? Why not just give it a good push away from the station earthwards?

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1. Re:Why not just push the old one down to Earth by ColdWetDog · 2013-12-21 09:25 · Score: 1
  
  Failure analysis. Didn't you see '2001'?
  
  --
  Faster! Faster! Faster would be better!
2. Re:Why not just push the old one down to Earth by Anonymous Coward · 2013-12-21 09:32 · Score: 0
  
  Because that'd simply put both objects into slightly different intersecting orbits.
  Newton's laws and orbital mechanics are a bitch.
3. Re:Why not just push the old one down to Earth by techno-vampire · 2013-12-21 12:30 · Score: 1
  
  If memory serves, what you'd want to do is push it backwards in its orbit, slowing it down so that it drops into a lower orbit. Of course, human muscle power isn't going to be enough to make a measurable difference, and getting it low enough that atmospheric drag will finish the job is going to take quite a bit of delta-V.
  
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4. Re:Why not just push the old one down to Earth by cusco · 2013-12-21 15:40 · Score: 1
  
  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.
  
  --
  "Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
5. Re:Why not just push the old one down to Earth by crutchy · 2013-12-21 22:14 · Score: 1
  
  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.
6. Re:Why not just push the old one down to Earth by cusco · 2013-12-22 04:39 · Score: 1
  
  True enough, but it's an ammonia refrigeration unit, there's only so much lightening that you can do to something like that.
  
  --
  "Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
7. Re:Why not just push the old one down to Earth by wagnerrp · 2013-12-22 05:53 · Score: 1
  
  Actually, atmospheric drag will finish the job. The ISS needs to get regular boosts, around once per month, to maintain altitude. It uses around seven tons of propellant each year for orbit maintenance. Now granted, this pump will be considerably denser than the ISS as a whole, and thus would descend slower, but re-entry would occur in under a decade.
Yeah... by Anonymous Coward · 2013-12-21 09:52 · Score: 1

"Ammonia".... Howard f-ed up the space-loo again...
Bravo by guygo · 2013-12-21 09:52 · Score: 1

These guys are amazing. Well done! Working without gravity to help you is quite an amazing trick for Earth-based monkeys. I am always greatly impressed by the training and skills of all these people who actually climb out of their tin can into open space. More than anyone I think they fit the spirit of the 50s and 60s "astronaut" image. Excelsior!
Smooth spacewwalk by rossdee · 2013-12-21 10:28 · Score: 2

If you're walking in space and its bumpy then you have a big problem
Human achievement by BringsApples · 2013-12-21 10:49 · Score: 2

The space station travels at roughly 17,500 MPH. They're working in (this is per the folks that make the suits) anywhere from -100F to +235F. Good job guys. It really takes a lot of people to crunch numbers and possibilities of failure, what to do if failure occurs, and how to do all of this within certain time restrictions. If mankind can claim any sort of technical achievements (I know most here would like to boast their computer skillz), this, in my mind, is a fine example of folks working together at far distances, and through many challenges. Bravo guys and gals!

--
Politics; n. : A religion whereby man is god.
1. Re:Human achievement by drinkypoo · 2013-12-22 03:38 · Score: 1
  
  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.
  
  --
  "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
2. Re:Human achievement by BringsApples · 2013-12-22 04:21 · Score: 1
  
  Don't get me started. I'll go 17,500 MPH, using your FACE as reference! :)
  
  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.
  
  --
  Politics; n. : A religion whereby man is god.
3. Re:Human achievement by tonytally · 2013-12-22 04:49 · Score: 0
  
  You are correct except for one thing. If we didn't send people up there in the first place, we wouldn't need all this panic fixing. Those geology rovers on Mars have been there for how long? Sending people increases the complexity and cost enormously; but it is much more sexy and the PR guys think it necessary. Pity.
I'm curious... by Doctor+Device · 2013-12-21 11:08 · Score: 1

I'm sure there are plenty of reasons, but why does the ISS use a complicated ammonia-based refrigeration system? I had always assumed they just dumped the waste heat into space with something akin to the heat sink in my computer.

--
-It is by will alone I set my mind in motion.
1. Re:I'm curious... by Anonymous Coward · 2013-12-21 11:37 · Score: 0
  
  Air.
  Vacuum.
2. Re:I'm curious... by cbhacking · 2013-12-21 11:49 · Score: 4, 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.
  
  --
  There's no place I could be, since I've found Serenity...
3. Re:I'm curious... by Redmancometh · 2013-12-21 11:55 · Score: 1
  
  There is nothing in the vacuum..so there is a specific heat of roughly 0.
4. Re:I'm curious... by Redmancometh · 2013-12-21 11:56 · Score: 1
  
  Also you can't blow it out...because there isn't air.
5. Re:I'm curious... by Doctor+Device · 2013-12-21 13:00 · Score: 1
  
  I realized after I posted that I'd forgotten the whole "a heat sink needs a medium to transfer the heat to" part. I appreciate the cogent explanation, though. my knowledge of the intricacies of spaceflight basically stops at Kerbal Space Program.
  
  --
  -It is by will alone I set my mind in motion.
6. Re:I'm curious... by cbhacking · 2013-12-21 22:05 · Score: 1
  
  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 will get hotter than any other part of the system, but that's how you get efficient radiative cooling. The rate of direct conduction of heat between materials is also dependent on the difference in their temperatures, but you can build an effective conductive cooling system without requiring a huge temperature difference; not so for radiative cooling.
  An interesting case of a sci-fi movie that (very quietly) gets it right: Avatar. Near the beginning of the movie, as the starship approaches Pandora, you can see it has large fins extending out around the engines, glowing red. Those are heat sinks / radiators, so hot that the blackbody radiation has moved beyond the infrared and into the visible spectrum.
  
  --
  There's no place I could be, since I've found Serenity...
You can't feel gravity by tcstoehr · 2013-12-21 11:47 · Score: 2

Adespoton is spot on. No gravitational force can be detected when in "free fall" which is what space orbit is. Even as gravity may grab you and accelerate you towards a large mass, there is no bodily sensation whatsoever. Every molecule of the bodily is (almost) identically effected. There is nothing to cue the brain that gravity is pulling you, even as you may change direction as a result of it. Very difficult for most people to understand this who are used to feeling earth under there feet, air against their skin, and visual references all around.
1. Re:You can't feel gravity by CohibaVancouver · 2013-12-21 12:55 · Score: 1
  
  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.
2. Re:You can't feel gravity by Em+Adespoton · 2013-12-23 17:33 · Score: 1
  
  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.
The 780 pound? by Anonymous Coward · 2013-12-21 12:00 · Score: 0

That weighs 0 pounds, why even mention weight in a weightless environment? Wouldn't the mass of the object make more sense, or the actual dimensions?
1. Re:The 780 pound? by Anonymous Coward · 2013-12-21 12:50 · Score: 0
  
  Pounds are a unit of mass, not weight. That'd be measured in pounds-force.
2. Re:The 780 pound? by wagnerrp · 2013-12-22 06:00 · Score: 1
  
  Pounds are a unit of weight, measured using a scale, not a balance. Slugs are a unit of mass. Pounds-mass is just retarded.
3. Re:The 780 pound? by wagnerrp · 2013-12-22 06:05 · Score: 1
  
  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.
4. Re:The 780 pound? by wonkey_monkey · 2013-12-23 00:54 · Score: 1
  
  Pounds are a unit of weight
  There is also a unit of mass called the pound.
  
  --
  systemd is Roko's Basilisk.
5. Re:The 780 pound? by wonkey_monkey · 2013-12-23 00:56 · Score: 1
  
  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.
  
  --
  systemd is Roko's Basilisk.
6. Re:The 780 pound? by wagnerrp · 2013-12-23 06:18 · Score: 1
  
  Using pounds as a unit of mass is not sensible, as it is a scaled unit that must carry an arbitrary factor along with it if it is to be used in calculations.
7. Re:The 780 pound? by wonkey_monkey · 2013-12-23 11:27 · Score: 1
  
  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.
  
  --
  systemd is Roko's Basilisk.
8. Re:The 780 pound? by wagnerrp · 2013-12-23 11:41 · Score: 1
  
  I never suggested using pounds as a unit of mass.
  http://slashdot.org/comments.pl?sid=4585781&cid=45765969
9. Re:The 780 pound? by wonkey_monkey · 2013-12-23 19:16 · Score: 1
  
  I never suggested using pounds as a unit of mass.
  
  --
  systemd is Roko's Basilisk.
"What're you bringing the rope for?" by rmdingler · 2013-12-22 00:57 · Score: 1

I am responsible for bringing often-times specialty tools and material to job sites.
Our motto is:
"The only way we'll need that is if we don't bring it."

--
Happiness in intelligent people is the rarest thing I know.
Ernest Hemingway