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More Solar Panel Problems For ISS
rufey writes "This week there have been two pieces of bad news from the International Space Station. First was the discovery of metal shavings inside a problematic rotary joint used to keep one set of solar panels in the optimal position for power generation. At the close of a subsequent spacewalk, after it was relocated to its permanent location, the unfurling of the 4B solar panel resulted in it tearing in two places. A spacewalk is now planned for November 4th to attempt to fix the tear. The upcoming spacewalk is not without risks, including the remote possibility of electrocution since it is impossible to stop the solar panel from generating electricity during the repair attempt. NASA says the ripped wing needs to be fixed or the solar rotary joint problem solved before any more shuttles can fly to the space station and continue construction. With a hard deadline of 2010 for Shuttle retirement, NASA does not have much wiggle room in the schedule in order to finish ISS construction."
Why don't they do the repairs at night?
Or rotate the panel so that it is side-on to the sun?
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If there were an easy way to fix this, NASA would have figured it out. Don't forget, these fix rovers millions of miles away by changing computer code. I'm sure any suggestion here on /. has been thought of already.
I prefer Flambe as apposed flamebait.
Why is 2010 such a "hard" deadline? Was it not created solely by politicians who wanted to divert resources to go to Mars? As such, can it not be moved just as easily as it was created? It is, after all, three years away. If we can't move deadlines that far out, isn't there a chance we're overplanning, and leaving ourselves completely vulnerable to unexpected circumstances, exactly like this solar panel issue?
"We can categorically state we have not released man-eating badgers into the area." - UK military spokesman, July 2007
Of course it's going to be the really shiny "NASA" kind, but still duct tape.
As for why they can't just wait for night, the period of the ISS orbit is about 93 minutes. They'd have to work fast.
See what I've been reading.
He will not be electrocuted, or at least if he is, he will survive.
Of all the crewmembers aboard the ISS/Space Shuttle, Parazynski is the most experienced.
If NASA were going to kill off a character, they'd send out one of the junior redshirts to do the repair job.
- RG>
Hey pal, this isn't a pleasantforest, so don't waste my time with pleasantries!
Because the night isn't very long on the ISS. From http://en.wikipedia.org/wiki/ISS: "...completing 15.7 orbits per day".
My UID is prime. Hah!
Good luck to them. I hope all goes well, the repair is made, and nobody gets hurt.
That bit about not being able to take it down for repair, well, that's going to make it into some future book on industrial design. Oh, and into future space stations. I hope.
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And I know there's going to be a ton of posts implying that the NASA folks should have thought of [insert idea here]. Of course they did.
I prefer Flambe as apposed flamebait.
Shouldn't he be in a spacesuit when he fixes it therefore shouldn't it be extremely well insulated?
I mean, the Emperor from Star Wars should be able to blast cosmic rays at him and he should just shrug it off like morning dew.
if you steal from one source, that is plagiarism, if you steal from many, well, that's just research.
(An upgrade to Hamlet's rhetorical question)
We're gonna need a bigger roll of Cello Tape.
A feeling of having made the same mistake before: Deja Foobar
yes but he is using one of the RED space suits... a sure sign he is toast.
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Since they are in orbit and the orbital period is about 93 minutes they only have about 40 minutes "night". Why is night not evenly split between "night" and "day" is because of the when you are in orbit the extra altitude keeps you out of earth's shadow for a about 10 minutes. This is similar to if you are on top of the mountain you will notice the ground below get darker before you do and if you are in a nearly 200 miles above the surface of the earth that extra sunlight time more that a few minutes. Since the solar panels are linked together to make power together the only way is to bypass the tear. However they need to look at what happen up close to find out where to bypass it and being this close their is a remote chance of getting the capacitor affect where even you are insulated but the equipment that carries you, the remote arm, is not so you will feel the electrical force going through you. Ouch!
remember there are metal joints in the space suit and as he is floating inside the suit, who knows what metal he could in contact at any second.
Mod parent insightful, not funny, as it is valid question, and was indeed asked ("why not limit the the repair time to night passes") on yesteray's NASA's mission status briefing. The response was that sacrificing basicly spending half of the spacewalk to do nothing is not worth the added safety - note that the 'electrocution' mentioned is very extreme case, as the panels itselves are coated with insulation, the tools are insulated etc, but as they spend years in space and were damaged, there is concern that there *might* be some scratch in the coating or anything, that *may* conduct, and it *may* touch some of the EVA equipment, and that *may* conduct through the electronics (the space suit is full of sensors and stuff that touch the body), and it *may* go through the heart of the astronaut, and in really really extreme case that *may* end up with electrocution. Of course that word was immeidately picked up by the press, and it ended up with the staff saying that if on of the reporter in the room leaned back to his microphone, that there is about equal chance he may be electrocuted.
Forgive my ignorance, but are they going to do this spacewalk repair bare-handed? Is there at least two exposeds part of a spacesuit that is conductive from the outside to the inside (you need two points to complete a circuit)? If there's something like aluminum ring seals at the wrists, have another crewmember double wrap them with duct tape or electrical tape before sending them outside.
How does electrocution come into play with this? Dielectric breakdown through the suit shouldn't be an issue as I seem to recall on a previous story that we're talking roughly 160VDC potential, nearly the same as US household wall socket voltages. Deadly? Yes. Arc through your spacesuit (twice)? Hardly.
The partially unfurled solar wing is producing power, and there is no way to turn it off
Man, do we need one of these things on Earth, RIGHT NOW!
He who knows best knows how little he knows. - Thomas Jefferson
On a more serious note, don't the solar panels have switches to disconnect them from each other? They are like batteries connected in series, so you just need to break a few connections to lower the voltage and make each subset electrically floating with respect to the others. It's like when you were little and connected a bunch of 9V batteries together and got a big shock.
Because NASA Needs A Solar Array... and they are afraid of 30-Days-of-Night.... (Didn't want Halloween to become Hell-O-Ween?)
Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
Simple solution: make sure his tether is non-conducting. Use one of those MMUs so the astronaut can be autonomous instead of on an umbilical. Or am I overlooking something?
The panel cannot withstand the stress of rotation while the tear exists. The spacewalk will repair the panel to the point where it can be fully extended. Once fully extended, the tension on the panel helps it withstand the stresses of rotation.
The damage to the joint affects the opposite panel.
and doesn't touch ground with the other, he should be fine. Wait, how does one ground himself while in space?
Jerkoffs from Lockheed Martin designed these problem-plagued arrays. Furling/unfurling the arrays has been a problem from day one. Recall the problems the HST had with array warping? They were designed by the same idiots at Lockmart. The problems went away after the last shuttle servicing mission when NASA installed proper rigid Boeing arrays.
Yes, that is a valid concern, but that is not from TFA. In fact, the only mention of electrocution comes directly from the slashdot editor's/submitter's summary:
including the remote possibility of electrocution since it is impossible to stop the solar panel from generating electricity during the repair attempt.The above quote rather explicitly attributes the danger of electrocution from electricity being generated from the solar panel, not the discharge from static build up.
The short of it (no pun intended): Electrocution from the electrical current from the solar array? No. Electrocution due to a static discharge? Possibly yes, but it's not the source of the lethal electricity alluded to by the summary.
The solar panels were designed to generate power from illumination either on the front or the back (although they are not as efficient when back-illuminated.) This allows the panels to gain a bit of power from albedo illumination (i.e., light reflected from the Earth). So turning them backside to the sun wouldn't stop them from generating power.
http://www.geoffreylandis.com
Hence I said "side-on".
But, the stabilizing wires are tangled in the array, so moving at all (apparently) will tear it more.
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At the rate things normally break and the lack of a budget for replacement parts, exactly what do they expect to work in 2010 when construction ends?
Silly, the astronauts would be asleep at night. :-P
A marriage is always made up of two people who are prepared to swear that only the other one snores.
If you read the article, in fact if you had merely completely read the summary, you would understand that solar panels can not be turned off. Even in the absence of direct sunlight (which only occurs for a maximum of 36 minutes each orbit) they will still develop some power due to reflected light. You would also have noted that electrocution is a "remote risk."
If the problem were anywhere downstream of the sequential shunt units, they could lockout/tagout (btw, there is no OSHA in space), but it's upstream.
This is not design negligence. It's a fundamental fact of photovoltaics.
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Many here voice their opinion that the space station os a waste of money. This solar panel incident has vindicated the ISS supporters: Testing such technologies in low earth orbit is a needed. You would not want to experience that on an interplanetary flight.
We may not necessarily develop new technologies but engineers can test solutions "in the field" and hone the skills needed to develop working solutions for voyages where no rescue/repair is possible.
"...since it is impossible to stop the solar panel from generating electricity during the repair attempt..."
-Er... Houston, we have a problem
-What is it now?
-you idiots forgot to install the fuse box