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Ulysses Spacecraft on its Last Legs
Posted by
CmdrTaco
on Sat Feb 23, 2008 11:54 AM
from the at-the-end-of-the-tour-when-the-road-disappears dept.
from the at-the-end-of-the-tour-when-the-road-disappears dept.
doconnor writes "JPL announced that Ulysses' mission will be ending after 17 years. The power generated by the decay of a radioactive isotope has been slowly decreasing. To conserve power its main transmitter was shut off. Unfortunately due to a fault in its power supply it cannot be turned back on. The team plans to continue operating the spacecraft in its reduced capacity, using the alternate S-band transmitter, for as long as they can over the next few weeks." Congratulations to all the geniuses involved in this one.
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Ulysses Spacecraft Not Dead Yet 78 comments
iminplaya sends in the good news that reports of the death of the Ulysses mission are premature. (We've discussed the impending shutdown of the 17-year-old mission a couple of times this year.) Ulysses is a joint NASA / ESA mission to study the sun from an orbit inclined almost 90 degrees from the ecliptic. From the Planetary Society blog post: "Ulysses is not dead yet. ESA issued a statement in February saying that, as Ulysses' radioisotope thermoelectric generators were running out of power, the spacecraft would likely die some time this year. The actual death blow to the spacecraft was likely to be the freezing of hydrazine fuel in a cold spot in a fuel line. Mission controllers found creative ways to prevent the freezing, but the solution was not a long-term one, and ESA had a ceremonial send-off and wrap-up of the mission in mid-June, announcing that the spacecraft would be shut down on July 1. However, it now appears that announcement was premature. ESA issued a statement on July 3 titled 'Ulysses hanging on valiantly.' And on Wednesday, the [Ulysses mission operations manager indicated] that Ulysses' voyage could actually continue for some time."
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Ulysses Space Mission Finally Coming To an End 45 comments
Dusty writes "After several false alarms, the Ulysses Mission is finally ending. According to the Spacecraft Operations Manager's latest status report, the last track will be on 30th June 2009 from 15:25 until 20:20 UTC. 'We've tried to bolster our dwindling tracking allocation with some success
by grabbing antenna time released on short notice (mostly by the Spitzer Project). However, weekly data return figures are now typically 10% or less. And soon, even 512 bps from 70m antennas will be a thing of the past.'
Further details about Ulysses' 18-year mission are available from NASA and the ESA. We discussed the failing spacecraft last summer when it looked like its fuel was going to freeze, but through clever engineering, experts managed to squeeze out another year.
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Geniuses (Score:5, Insightful)
I'm not sure if the congratulatory statement was sarcastic or sincere, but I hope it was sincere. From the article:
"The joint NASA and European Space Agency Ulysses mission to study the sun and its influence on surrounding space is likely to cease operations in the next few months. The venerable spacecraft, which has lasted more than 17 years or almost four times its expected mission lifetime, is succumbing to the harsh environment of space."
Further on the article states that the lifetime was expected to be five years, so three times, not four, but still, a spacecraft tripling its expected useful life is a strong testament to the skill of its engineers.
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...so three times, not four, but still, a spacecraft tripling its expected useful life is a strong testament to the skill of its engineers.
Our Martian Robotic Geologists' (Spirit and Opportunity) primary mission was only supposed to last 90 days. And they landed in 2004. So that makes them somewhere in the neighborhood of 12 times older than they're supposed to be.
This kinda makes me wonder if NASA and other space agencies purposely over-estimate the useful lives of their spacecraft.
Re:Geniuses (Score:5, Insightful)
This kinda makes me wonder if NASA and other space agencies purposely over-estimate the useful lives of their spacecraft.
I think it's a testament to how difficult it is to estimate the challenges of space exploration. To me, keeping a vehicle operational on another planet we've never set foot on with no opportunity for maintenance sounds damn hard. Doing that for the first time, I imagine 90 days sounded like a stretch. The fact that they've done it for over 3 years to me is one of the great successes of space exploration.
Parent
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How long will it take? Double it, then add in a factor of two for contingency.
How long will it last? Halve it, then take a factor of two for contingency.
If it moves, oil it. If it doesn't move, hit it with a hammer 'til it does move, then oil it.
Obligatory Trek Quote
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Re:Geniuses (Score:5, Informative)
It's easy to make such a statement if you didn't know the history of rovers & other landers.
Before the Rovers Spirit & Opportunity, there were NO rovers that lasted 90 days on another planet before dying. The predecessor, Sojourner, lasted 83 days. Before that, I think the record was 56 days. 90 days was a good goal. They thought the solar panels would just get covered with dust. They could have put on dust cleaners, but that has a weight penalty, and they decided to use the weight for science payload. They got lucky when they found they can get cleaned from the wind storms.
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Re:Geniuses (Score:4, Interesting)
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Re:Geniuses (Score:5, Insightful)
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Re:Geniuses (Score:5, Interesting)
Sure, Mars has winds where Luna doesn't, but given the thin atmosphere, it's not like you have to worry about them blowing the rover away or anything. As it turned out, they were just right to blow accumulated dust off the solar panels. Yes, the wind means dust might be more likely to get into the mechanisms, but at least it's smooth rounded dust. Lunar dust is jagged fractal surfaces all the way down, highly abrasive; the saving grace is that it only gets kicked up by your wheels spinning or a nearby impact. (That's another difference -- the Martian atmosphere is enough that you don't have to worry about micrometeorite impacts, which you do on the Moon.)
Venus is of course a different question; nobody's gotten a Venus-lander to last for more than a few hours. The surface temperature is twice as hot as a pizza oven (hotter, in fact, than Mercury's surface), and the pressure is about the same as 3000 feet underwater.
Parent
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Pathfinder lasted 83 days. Sojourner could still be operating as far as we know.
Re:Geniuses (Score:5, Insightful)
This kinda makes me wonder if NASA and other space agencies purposely over-estimate the useful lives of their spacecraft.
There's a hidden premise here. The premise is we can know the expected lifetime of something that:
Which do you think is more likely?
The engineers all know how long the thing is going to last, but lie about it to make themselves and NASA look good.
or
They really don't know how long it's going to last, but make some very conservative estimates about the above unknowns, to make sure it'll last at least as long as the time frame it's supposed to. Sometimes those guesses turn out to make the thing last a lot longer than it needed to be.
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Re:Geniuses (Score:5, Insightful)
The rovers on mars almost died when their flash memory filled up, because they did not intend to survive long enough to gather so much data, that the capacity of their flash was deemed more than enough. This alone is good evidence that they aren't really intending for things to run this long, just sometime they do a really good job AND get really lucky. Go read about the Expensive Hardware Lobbing [anl.gov] to get an idea of just how easy it is to make a mistake, and how catastrophic such mistakes are. Even with how much care goes into these things, we still don't keep terribly good odds.
I don't know all the reasons the rovers are still running, but I've heard several. The crippling flash space problem was averted because of an automatic reboot, in addition to an automatic failsafe mode, the combination of which allowed them to get in and clear disk space. The rover with the dead wheel, they were able to disengage its motor so it didn't eat up power and drag on the ground (not turning) and that again isn't something you'd necessarily ever expect to need to do, but they added that ability anyway and it paid off. I'd bet there are at least a dozen other "plan ahead" safeties that have saved their bacon too.
From Mariner 2's entry on EHL: On September 8 17:50 UT the spacecraft suddenly lost its attitude control, which was restored by the gyroscopes 3 minutes later. The cause was unknown but may have been a collision with a small object. Then, on November 15, one solar panel failed. However, the probe got within 34,773 km of the planet on December 14 19:59:28.
The odds of it hitting something out in space has to be incredibly slim, but they installed gyroscopes anyway, and as a result were able to continue the mission. You can't really factor that in when trying to calculate the life expectancy of a project like this. All you can do is build it the absolutely best you can, and hope you don't get mugged by too many problems at the same time.
Although the ppl at NASA are certainly skilled, I don't think we can call any of them "experts" at this space exploration thing. They may be the best we've got, but lets face it, there's a lot we still don't know, and we're not able to build experience very quickly. We're total n00bs in space. I don't think we over-estimate anything, we just get lucky now and then. Building in failsafes and options gives us one or two more extra chances sometimes when something we do doesn't work, and that can turn a single 5 year mission into four or five learning experiences before it finally breaks beyond hope, rather than one.
When Mariner 3 failed to eject its heat shield, that one mistake totally screwed the entire mission after a very long wait. Instead of tinkering with various ways to fix the problem remotely with your available options, Game Over. Wait another 5 years and try again. Those are the painful lessons they try to avoid by what is sometimes perceived as over-engineering or under-estimating.
Parent
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I have been involved with space flight projects, and you always hope that they last "forever." However, that scares program offices and the budget types. So, you specify a short, sweet, do-able missions, get money for that, and, if you are successful, hope that you can get money to extend it. If you are not successful, well, then it didn't really matter, did it ?
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Hey genius, don't you mean, under estimate?
That aside, lets take the problem straight on and consider the mars rovers. You are the engineer. You don't have anything remotely resembling a clue as the abrasive qualities or the dirt and dust on Mars. You have an inkling of a clue about wind and such, but Martian surface weather is still a pretty big mystery. You have to build a device that is mobile, must supply power to all kinds of instruments, it has to communicate to a orbiting platform that is not in
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You know that this electric engine designed to work between 2V and 10V will still be working well under 15V and will only begin to make strange noises and smoke around 30...
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Who exactly makes determines the expected life of these things? Is it the scientists who are working on them? 'Cause if you want to be a glass-half-empty kind of guy, then you could say that it's a poor testament to their ability to predict expectancies, rather than to exceed them.
- John
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It's kinda like your doctor - I'd rather tell you that I want to run some tests because I suspect disease, have you pay for such tests, and then have you breathe a sigh of relief when disease is ruled out than just tell you outright to stop being such a crybaby it's all in your head (except of course when it's pretty
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your first mistake (Score:2)
Cheers,
Dave
Lots of PhDs Awarded (Score:5, Interesting)
If you go to the publications [esa.int] page for Ulysses, you'll see that about 60 PhDs have been awarded for Ulysses research, in addition to vast numbers of research papers and other article. By any count, this mission has been a success. Congratulations to all involved.
17 years is a long time, Ulysses (Score:4, Funny)
Congratulations (Score:2)
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And as well:
"We expect certain parts of the spacecraft to reach 2 degrees Celsius pretty soon," said Richard Marsden, ESA project scientist and mission manage.
You can feel "American pride", but it makes you look stupid when it's misplaced.Sarcasm Is Not Recommended. (Score:4, Insightful)
For information on how successful the Ulysses mission has actually been, including its recent historic third pass over the north solar pole, Please refer to the Ulysses home page at JPL:
http://ulysses.jpl.nasa.gov/ [nasa.gov]
In any case, I'd like, perhaps, to suggest that the article post could either have been written, or otherwise reviewed, with more editorial skill. Then again, maybe that's asking too much. And that statement was not intended to be sarcastic.
Cheers,
--joe.
Solar Polar Mission (Score:5, Insightful)
thus observe the Sun from high solar latitudes. It fulfilled that mission and lasted long enough to observe both
the North and South poles of the Sun. I would say it was fully successful.
It is not uncommon for the death of old spacecraft to be messy or even sloppy - the Viking 1 lander was killed by a programming bug -
but that does not detract from their earlier successes.
Kudos to the Ulysses team (Score:5, Insightful)
By contrast, Ulysses is traveling in one of the most hostile environments we can imagine. Everything in the shade is approaching -400F (IIRC) while everything on the side facing the sun is getting blasted with the full fury of solar radiation. There's no way to reach it for maintenance. It's technology is 17 years old now. It has no protection other than its own skin from any micro-meteors it encounters. And it has been running continuously since it was launched. You've gotta admit that's an impressive feat. Yeah, I'd say the NASA engineers responsible for Ulysses are 1) definitely geniuses, and 2) very deserving of congratulations.
And it's journey's just beginning (Score:2)
Watch out other NASA satellites (I'm looking at you, Cassini): I'd advise not making any moves on Penelope [nasa.gov].
And here's how it all begins (Score:5, Interesting)
http://www.youtube.com/watch?v=bqmYWgivsHw [youtube.com]
Thank you Ulysses!
Look at me still talking when there's science todo (Score:4, Funny)
I'm making a note here: HUGE SUCCESS!
It's hard to over state my satisfaction.
Awesome! (Score:5, Informative)
Their site [esa.int] is amazing! It shows all of the instruments and links to the data they've provided directly. For instance, the DUST [esa.int] instrument measures dust impact events (imagine that). You can use the heliocentric latitude and longitude for these thousands of events to track the spacecraft position throughout it's 17 year journey. A nice readme [esa.int] file explains the structure of the data file [esa.int]. That's just one of the 12 scientific instruments. Very cool stuff...
On another note, why are people saying four times as long as they expected? 17 years is closer to three times the original five years than four. You can't really say it's lasted four times as long as expected until after it has lasted 20 years.
Ulysses is beautiful (Score:4, Interesting)
For those that havn't seen pictures, Ulysses is one of the most beautiful spacecraft ever built. Some future archeologist will love getting this for their museum: http://upload.wikimedia.org/wikipedia/commons/6/68/Ulysses_spacecraft.jpg [wikimedia.org]
Covered mostly in gold and other types of metals, the craft looks more like something out of a movie than a real craft.Re:D'oh (Score:4, Insightful)
"- has lasted more than 17 years or almost four times its expected mission lifetime"
Yeah, They only got 4 times the usefullness out their investment as they'd originally hoped to get... They must be furious.
Parent
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Re:D'oh (Score:5, Funny)
Parent
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Re:D'oh (Score:5, Insightful)
4 times the usefulness" is a bit of NASA doublespeak.
However, in this case, it really is on the tail end of the extended mission. The reason they wanted to shut the xband transmitter off was that the isotope generator is winding down. The output of the isotope generator is quite predictable. That is, they KNEW it would be out of energy by now. Had they been able to toggle the xband transmitter and divert energy as planned, it would have bought a second extended mission of about 2 years. NASA has done a pretty good job w/ Ulysses.
Meanwhile, given the extreme hostility of space and the complete impossability of making repairs once launched, the practice of overdesign for the primary mission is justifiable. The extended secondary mission is the simple practicality of if it's still working, might as well enjoy it.
Parent
Re:D'oh (Score:5, Informative)
I know reading articles goes against everything slashdot stands for, but doing it from time to time can make you smarter.
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5 year mission (Score:5, Funny)
Don't look at me - I'm still p*ssed off that the Enterprise's original 5-year mission got cancelled after 3 years, you ignorant clod!
17 years ... I can just see it now. Imagine how fat Shatner would have been by the series end? Oh, we don't have to imagine ... but he'd still be getting all the green chicks ...
And Dr. McCoy could have actually said "I'm dead, Jim!"
Parent
Re: (Score:3, Interesting)
Just sit right back and you'll hear a tale,
A tale of a successful trip
That started from a tropic space-port
Aboard this tiny ship.
The console-mate was a mighty science man,
The project manager brave and sure.
Seven instruments set sail that day
For a five year tour, a five year tour.
The sun's plasma started getting rough,
The tiny ship was tossed,
If not for the courage of the fearless controllers
Ulysses would
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Re:D'oh (Score:5, Informative)
Parent
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I can only imagine the fit NASA had when they found this out. Millions of dollars for what is now a giant hunk of metal. I sure hope they got something out of the project before transmission was cut off.
Did you read the first sentence in the summary about "after 17 years"? They've gotten all they were supposed to get out of it and much, much more. This was a last-ditch effort to having it work in a semi-reduced capacity for another two years rather than die now. It is dying because the power source is dying, which is pretty much the limit for how long something can operate even if everything else keeps working normally (which was also why the Mars rovers were supposed to die - no power). The only real per
Re:D'oh (Score:4, Informative)
In space, even solar power is far from perminant. Over time, solar cells are destroyed by particle radiation. A solar sail will gradually be filled with pinholes degrading it's performance until it finally falls apart.
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Re:D'oh (Score:4, Insightful)
[/sarcasm]
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Re:D'oh (Score:4, Insightful)
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Oh, wait, slashdot... my bad, carry on
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60 watts should be enough for anybody.
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