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Space Station Solar Equipment Showing Damage
bhmit1 writes "The latest space walk has turned up some bad news for the problematic solar panels: metal shavings. From the article: "The rotary joint, 10 feet in diameter, has experienced intermittent vibrations and power spikes for nearly two months. Space station managers were hoping a thermal cover or bolt might be hanging up the mechanism. That would have been relatively easy to fix, so they were disheartened when Daniel Tani radioed down that metal shavings were everywhere. 'It's quite clear that it's metal-to-metal grating or something, and it's widespread,' Tani said.""
That's not metal-on-metal grating in the bearings, that's just some sick bastard playing Yoko Ono.
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
Oil does not work in space. It either freezes or evaporates. In fact only some "solid lubricants" like graphite and MoS work to a point.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
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...or something.
Thanks for the technical breakdown. Sounds like the way Beavis would describe it. That's comforting. Or something...
I noted that they intend to fit a replacement joint, and are limiting the travel of the solar panel(s) in the mean time. My question is, do they know what the source of the problem actually is? Is it a manufacturing defect, damage or wear and tear in the currently fitted joint? If it is, replacing it is a reasonable solution. But if it isn't - i.e. if there's a design or operational problem - replacing it will just be a temporary band-aid, and the same thing will happen again sooner or later.
Towing in space has been done before. Grumman sent North American Rockwell an invoice for towing their crippled spacecraft home. The rate per mile seems pretty reasonable too.
All joking aside, this is going to be a bear to fix. The best scenario would be that the drive gear was munching an insulation blanket. The debris would be friendly to space suits, and should only be labor intensive to clean out. If the gears are grinding on each other, the debris will be sharp and hard. That would be "bad" and I'd expect NASA to seriously consider returning the entire assembly to earth for repair. Expensive, but much less likely to kill someone.
I'm of the opinion that the drive system on this beast is probably over-engineered. It should resemble a Ford F-150 differential - loose tolerances, and designed to run for many millions of rotations without much maintenance. There's absolutely no need for the solar array to have precision pointing capability. I really do hope that the problem isn't due to over-engineering, but I wouldn't place a bet.
I was gonna suggest using a dustbuster to sweep up the shavings... but there's nothing to suck...
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
SJW: Someone who has run out of real oppression, and has to fake it.
"Wow," said his spacewalking partner, Scott Parazynski. Its nice to see those "Keanu Reeves Linguistic School" classes paying off for astronauts.
Mit der Dummheit kämpfen Götter selbst vergebens
seen on a sign in a mechanic's garage:
Labor $10.00 Hr.
If you watch $15.00 Hr.
If you help $25.00 Hr
Politics is Treachery, Religion is Brainwashing
Even if we just assume they know so much more (which certainly used to be true in the past when they basically had the monopoly on staying up there long-term), the answer is: depends.
Globally, for the world as a whole, sure. Locally: no. If you never do it yourself but always ask the others they will get better and better, and you'll depend on them more and more. That's specialization all right, and according to economic theory that's a good thing. You just have to make sure you have something of equal or greater value to trade with... because if you don't, and I'd say in the foreseeable future there won't be many things more high tech (and therefore potentially valuable) than space-faring knowhow, you are screwed. Unless you believe that human nature is going to change completely.
Opening this thing up would be something like trying to rebuild an Automatic Transmission, then add the complexity of doing this in micro-gravity. It would probably be easier for NASA to send up a complete replacement instead of trying clean out all of the metal shavings and replace the parts that are damaged.
Homo homini lupus
"It's quite another to get the metal on metal thing going and getting stranded in space"
They have spares on board. Excepting the fact that it came as a surprise (a similar setup is ok), this is a non-issue.
over-engineering doesn't mean tight tolerances or precision parts. It means you just spent 3/4 of your budget to go from 95% accuracy to 96% when you only needed 95%.
In the original scheme of things -- i.e. back in the late 1970s when the Shuttle was being built -- the plan was that while the Shuttle would carry the vast majority of "medium size" payloads, they'd keep Delta around for small payloads (Delta has been upgraded quite a bit since then) and Saturn V around for the large payloads.
Needless to say, that plan was scrapped early on. Probably just before they overhauled the VAB and Pad 39 to make them Shuttle-compatible but Saturn V-incompatible.
-- Alastair
They supplied part of the computer system and the O2 Generator.
The Russians also provide two or three components and a second maneuvering system. They provide the only reliable supply vehicles and as I understand it, there's a considerable part of the orbit that's over Russian space.
In addition, they have never done anything near this big. As it is, the ISS is already double the mass of MIR, and it will go up by 50%. In addition, it is about 50% more living volume than mir and will still double over the next 2 years. This is WELL beyond what russia has done. This is all an new learning experience for the world. Fortunately, this experience will enable us to go to the moon and mars a lot cheaper and faster.Only three times the mass of MIR and you claim it's "WELL" beyond something the Russians have done? Nonsense. As I see it, there are a number of innovations in the structure and construction of the ISS, but the raw size isn't one of them.
Heck, look at China. Their space program is now outspending yearly what Apollo did at its' height. And with that, they launch a fraction of the flights that did and currently do. That is because they are busy trying to acquire the same technology (generally buying it from Russia or simply stealing it from NASA and RSA).
Where does that claim come from? Last I googled, China claims it only spends two billion a year. In comparison, when you adjust for inflation, NASA spending in the 60's peaked above $25 billion in 1996 dollars.These *were* designed to run for many rotations. The design specs for the SARJ (Solar Alpha Rotary Joint) were that the 10.5'x2.5', 2,500lb structure would rotate at 4 degrees per minute without imparting vibration to the laboratories that would mess up the microgravity experiments, for a minimum of 15 years. They also have to transfer 60kW of power at 160V while rotating through a "roll ring". These were the design specs, and they were engineered around that; this break was not supposed to happen. That's why this is considered an anomalous event. It's not a case of an insufficient design goal.
One thing that a lot of people don't realize is that there's still a tremendous amount of stuff that we don't know about living and operating things in space. It's deceptively similar to our world; just picturing it being like an Earth where you can't breathe and you can have enough velocity to fall in a circle simply doesn't cut it.
Example: TSS-1R. Space Shuttle Columbia deployed this as part of NASA's series of experiments with orbital tethers (for "hanging" craft from other craft and for raising and lowering orbits). When the tether was 19.7km out of the desired 20.7km deployed, it snapped. Evidence suggested arcing and burning in the tether. Why? The tether was at -3500VDC compared to the orbiter, with no current flowing through it. A minor defect in the tether's insulation left the conductive core exposed to space. Unexpected trapped gas in the insulation bubbled out in the vaccuum of space. This gas created a path for conduction to the orbiter, creating a plasma arc that burned away at the tether until the remaining strands failed under the strain.
In hindsight, it's easy to look at this and say, "Oh, we should have had a short-detection system." However, hindsight is 20-20. We've learned a great deal from past experiences, which unfortunately means that systems have to get more complicated. For example: where does the heat from running the drive motor for the arrays go? Why, it goes all over the place! It took an entire design study just to figure out where it would be going and what to do with it. Now picture unexpected current draws (creating more heat) from the metal shavings thrown into the mix, and what that will do for heat load, or what the metal shavings themselves could get into or allow to conduct unexpectedly. Things get tricky fast.
Too many people seem too eager to see a "finished product" in space. It's important that things like the ISS be seen foremost as learning experiences. In this case, I'm sure we'll see the same thing.
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Space travel, the trial-and-error way, eh? You mean, Wan Hu style? ;)
"Early in the sixteenth century, Wan decided to take advantage of China's advanced rocket and fireworks technology to launch himself into outer space. He supposedly had a chair built with forty-seven rockets attached. On the day of lift-off, Wan, splendidly attired, climbed into his rocket chair and forty seven servants lit the fuses and then hastily ran for cover. There was a huge explosion. When the smoke cleared, Wan and the chair were gone, and was said never to have been seen again."
Dunno about you, but I'd rather have it designed by the kind of people who'd rather sit down and calculate, instead of just doing the first dumb thing that comes to mind and see if it works.
Yes, _sometimes_, for a very narrow class of problems (like counting the bytes) the simplest way is to just do it and measure the number. But when you actually have to design something more complex, that quickly becomes a horrible idea. Even for something as simple as a watch, the probability to get it right by just throwing some parts together repeatedly and seeing if the result works, is close to nil. At some point you have to sit down and calculate the size of those cogs.
Plus, there is a lot of other stuff around you that happened only because someone sat down and calculated stuff, instead of good ol' dumb trial-and-error.
There's no way to invent a laser by trial and error, for example. The probability that just accidentally you'd have the right kind of material, and the right kind of coating at the ends, and the right light wavelength to excite it, and it's cut at the exact right length, is completely negligible. Humans have been cutting and setting rubies for millenia, and there are exactly _zero_ that started just emitting a laser beam by trial and error. It took someone calculating what happens there, before you could even know that a laser is possible, and how to make one.
In fact, pretty much the last major invention (that I know of) that was perfected by trial and error, was the light bulb. And, at least according to Tesla, that was a monumentally wasteful undertaking. To quote Tesla, "His method was inefficient in the extreme, for an immense ground had to be covered to get anything at all unless blind chance intervened and, at first, I was almost a sorry witness of his doings, knowing that just a little theory and calculation would have saved him 90 percent of the labor. But he had a veritable contempt for book learning and mathematical knowledge, trusting himself entirely to his inventor's instinct and practical American sense."
But even that stopped working for anything more complex than a light bulb. There's no way you could design a CPU nowadays by trial and error, for example. Even with specialized tools and massively simulating everything ahead, just one glitch sunk 3DFX. (Their Voodoo 5 was supposed to compete with the Geforce 1, but due to having to fix the malfunctioning chip design produced by their tools, it ended up competing with the Geforce 2 instead.) Now picture doing that layout by dumb trial and error instead. I wouldn't even try.
Heck, even in the job of counting bytes, sometimes the "American approach" (*) you describe would give the awfully wrong results until you've fully ported it. E.g., if the code was written with hard-coded constants for the saved data (which probably wouldn't be the case in Oracle's code, but I've seen it happen in other places), then compiling and running it would give the wrong results anyway. E.g., if someone saved an int by writing exactly 4 bytes to disk, it would still be 4 bytes for 64 bit code... and the very incorrect answer.
(*) As a side note, I hate thinking of those as "American approach" and "German approach", as it's really just the approach of whatever person gave that answer. I know there are plenty of Americans too who will stop and calculate, because otherwise the
A polar bear is a cartesian bear after a coordinate transform.
Magnetic bearings have their place but it is not in this sort of application. They excel where the physical contact of normal bearings would cause low lifetime at high speed but in other applications normal bearing are just so much easier to build, use, and replace that their limited lifetimes are not significant.
The space station failure is probably either related to a temperature coefficient mismatch between two parts that are now rubbing or physical damage. A magnetic bearing would not specifically solve either problem.