Slashdot Mirror
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
http://www.sigsegv.cx/
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.
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
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
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.
"We consider that six courts and an asylum claim are a rather odd way of returning to Sweden within a month."