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Groundbreaking Solar Mission Faces Chilly Death

Posted by timothy on Sat Jun 14, 2008 04:19 PM
from the hardly-knew-ye dept.
NASA Space Science
iamlucky13 writes "Over 17 years ago, the Ulysses spacecraft was launched aboard the space shuttle Discovery for a unique NASA/ESA mission. While nearly all other probes travel along our solar system's ecliptic plane, Ulysses used a Jupiter gravity assist to swing 80 degrees out of plane, carrying it over the sun's poles for an unprecedented view. During a mission that lasted four times longer than planned, it has flown through the tails of several comets, helped pinpoint distant gamma-ray bursts, and provided data on the sun and its heliosphere from the better part of two solar cycles. Unfortunately, the natural reduction of power from its radioisotope thermal generator means it is now unable to even keep its attitude control fuel from freezing, and NASA has decided to formally conclude the mission on July 1."
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Firehose:Groundbreaking Solar Mission Faces Chilly Death by iamlucky13 (795185)
[+] 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."
[+] 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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  • solar power? (Score:5, Funny)

    by Anonymous Coward on Saturday June 14 2008, @04:28PM (#23794165)
    They should have put solar panels on it.

  • Not really as bad as the blurb sounds (Score:5, Insightful)

    by the_humeister (922869) on Saturday June 14 2008, @04:29PM (#23794173)
    The mission lasted 4 times longer than was planned. Not too shabby (unless you compare to those Mars rovers that just keep going and going...). Sure beats having the mission end prematurely due to stupid things like not having enough fuel or computer errors.

  • Am I the only one that... (Score:5, Funny)

    by Anonymous Coward on Saturday June 14 2008, @04:39PM (#23794249)
    ...gets a little choked up thinking about that poor abandoned craft out there floating to oblivion with no one to talk to it.

    Ok, back to masculinity-land...

  • The Real Ulysses (Score:5, Funny)

    by gihan_ripper (785510) on Saturday June 14 2008, @04:40PM (#23794251) Homepage

    As the Greek Geeks will know, the real (legendary) Ulysses (aka Odysseus [wikipedia.org]) went on a ten-year odyssey returning home after the Trojan war. All assumed that Ulysses had died and his former wife was preyed upon by suitors seeking her hand in marriage.

    To cut a long story short, Ulysses killed all the suitors when he got home and was especially cruel to a turncoat goatherd, Melanthius. Ulysses cut off his nose and ears, pulled out his genitals for dog food, then sliced off his hands and feet.

    Let's home the satellite doesn't come back and find us messing about with the ISS.

    • Re:The Real Ulysses (Score:5, Funny)

      by DNS-and-BIND (461968) on Saturday June 14 2008, @05:04PM (#23794395) Homepage
      So, Ulysses was a neocon, eh?

      • Re:The Real Ulysses (Score:5, Informative)

        by Petrushka (815171) on Sunday June 15 2008, @12:55AM (#23797653)

        Yeah, because he sucked at navigation. Additionally, he was an idiot: All the things the gods warned him not to do because they would turn out to be bad, he did - and they went bad.

        Not a single statement there accurately reflects the Odyssey. The actual story, as opposed to the one you've made up, relates that:

        1. he took ten years because his men continually disobeyed his orders -- that's made clear in the first few lines --;
        2. he shacked up with Circe for a year (voluntarily);
        3. after he washed up on Calypso's island she basically held him prisoner for seven years. The story also relates how
        4. any time a god told him to do something, he did exactly that; and
        5. he is repeatedly described as having practically divine intelligence, and this is borne out by the various schemes he devises in the story. Even Athena compliments him on his deviousness.

        The reason you do not understand his appeal to the ancient Greeks is because your memory of the story bears little resemblance to the actual story.

  • I'd send it into the sun for one last splash (Score:5, Interesting)

    by crovira (10242) on Saturday June 14 2008, @05:14PM (#23794461) Homepage
    If the fuel's going to freeze forever after this orbit, I'd send it into the sun with all instruments lit up and see what it can record on the way down.

      • Re:I'd send it into the sun for one last splash (Score:5, Informative)

        by cyclone96 (129449) on Saturday June 14 2008, @06:01PM (#23794905)
        To change the orbit to intersect the sun, a tremendous amount of velocity would need to be removed from the current orbit. It would take more propellant to get it to the sun than it took to launch it from the earth in the first place.

        It's actually quite difficult to "hit the sun", the Messenger [jhuapl.edu] spacecraft will need to do one earth, two Venus, and 3 Mercury flybys over 7 years to "slow down" enough so that it can finally brake into orbit around Mercury with it's insertion motor.

      • Absolutely no way, is the short answer.

        Long answer - in order to get it into the sun, you have to reduce its rotational velocity from numerous miles per second down to zero. You'll remember your 0.5mv^2 - that's how much calorific energy has to be in those tanks to achieve that. Also, at those kind of distances, almost any kind of rotational velocity will be enough to achieve orbit - meaning the damn thing will almost certainly miss and turn into a rather odd comet, which will no doubt baffle our ancestors.

      • Re:I'd send it into the sun for one last splash (Score:5, Informative)

        by ozbird (127571) on Saturday June 14 2008, @06:22PM (#23795043)
        It doesn't carry anywhere near enough fuel for a sun dive.

        Most of the energy to get into its current orbit came from its PAM-S and IUS solid rocket boosters, with Jupiter kicking it out of the ecliptic. Until New Horizons was launched recently, Ulysses was the fastest ever artificially-accelerated object - that's how much energy we're talking about. Ulysses started out with 33.5kg of hydrazine maneuvering fuel, and was down to 8.4kg in May 2002. In a nutshell, you could use up all of the remaining fuel and not get anywhere near the Sun (perhelion distance is around 1 AU.)

  • NASA-style journalism (Score:5, Insightful)

    by TrueJim (107565) on Saturday June 14 2008, @05:14PM (#23794471) Homepage
    You can always tell when a story is based on a NASA press release. If the spacecraft exceeded its mission expectations, it's a "NASA spacecraft." But if it failed, it's a "Lockheed-built spacecraft" (or whichever contractor they decide to blame).

    For a change it would be nice to see NASA give kudos to whatever contractor built the successful spacecraft for them.

  • Control moment gyros (Score:3, Funny)

    by heroine (1220) on Saturday June 14 2008, @05:16PM (#23794477) Homepage
    Control moment gyros would have failed after 1 year & needed 17 servicing missions + 1 protest on capitol hill. U can't beat rocket fuel.

  • RTG lifetime (Score:5, Interesting)

    by Richard_J_N (631241) on Saturday June 14 2008, @05:48PM (#23794775)
    Quite a few spacecraft seem to run out of power due to failing RTGs. Admittedly, these are the ones that already perform *much* better than their design-lifetime (so Kudos to the designers), but why not just equip them with a little more of the relevant isotope? After all, the mass required is really quite small, and when the missions succeed, it would be great to have a 50+ year lifespan. Is there a good reason why the amount of isotope is limited, or is it just that nobody ever expected the craft to function so well and for so long?

    • Re:RTG lifetime (Score:5, Informative)

      by deglr6328 (150198) on Saturday June 14 2008, @06:23PM (#23795051)
      Because the problem of failing RTGs is not due to radioactive decay. RTGs use Pu-238 which has a half life of 88 years. It's just as hot as when it launched. The problem is dopant migration in the semiconductor heterojunctiontions (peltier junctions) of the part that creates the electricity. They degrade over time and put out less electricity for the same reason an LED fails gradually over time slowly emitting less and less light for the same amount of energy put in.
  • I think the mission shouldn't officially be over unless useful data stops coming back, and I would assume a probe even just floating around aimlessly might still broadcast back some kinda data.

    • Re:Mission's over? (Score:5, Informative)

      by Anonymous Coward on Saturday June 14 2008, @06:33PM (#23795101)
      Did you see that big dish on it? "Floating around aimlessly" = not pointing at the earth. You can't transmit to the earth without attitude control.

  • Here there's more (Score:5, Informative)

    by Dusty (10872) on Sunday June 15 2008, @02:07AM (#23798001) Homepage

    The European Space Agency had a press conference about the end of Ulysses on Thursday. Brief note and audio feed [esa.int]. Longer press release [esa.int].

    The video the Ulysses Legacy [esa.int] has a great summary of the mission, and of the problems it now faces.

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