Catch up on stories from the past week (and beyond) at the Slashdot story archive

 


Forgot your password?
Close
typodupeerror
×
NASA Space Science

Groundbreaking Solar Mission Faces Chilly Death 134

Posted by timothy from the hardly-knew-ye dept.
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."
This discussion has been archived. No new comments can be posted.

Groundbreaking Solar Mission Faces Chilly Death More

Groundbreaking Solar Mission Faces Chilly Death

Comments Filter:
  • attitude control.

  • solar power? (Score:5, Funny)

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

    • Re: (Score:2, Informative)

      by Anonymous Coward
      it does not provide thrust. for that you need to throw out some mass. or use HUGE solar sails.

      • Re: (Score:1)

        by fr4nk ( 1077037 )
        The RTGs don't provide thrust either... as TFS states, it's used (among other things) to keep the hydrazine tanks for attitude control from freezing. Also, solar panels wouldn't help much, because it's orbit extends as far as Jupiter's (with the periapsis being a little outside Earth's orbit).

        • Re:solar power? (Score:5, Informative)

          by NathanBFH ( 558218 ) on Saturday June 14, 2008 @07:27PM (#23795461)
          While this was certaintly true 17 years ago, it's interesting to note that we are now able to sufficiently power science craft with solar panels even as far as Jupiter. Check out Juno: http://en.wikipedia.org/wiki/Juno_(spacecraft) [wikipedia.org]

          • Re: (Score:3, Informative)

            by hubie ( 108345 )

            "Sufficiently power," of course, depends on your mission goals as well. An RTG will give you consistent power for a long time, whereas the solar cells will have issues managing eclipses and long-term degradation from radiation exposure. A Voyager-like flyby would be better suited for an all-solar approach rather than a Galileo-type orbit (and eclipse) all the time in strong radiation belts. History has also shown that it is far from trivial to deploy large solar arrays, even when you have humans present,

            • An RTG will give you consistent power for a long time, whereas the solar cells will have issues managing eclipses and long-term degradation from radiation exposure.

              The orbit of Ulysses goes from a perihelion of 1.34 AU, to an aphelion of 5.4 AU (period 6.2 years) (from a NASA position paper [nasa.gov]) ; that's a factor of 4.03 difference in heliocentric range and 16.24 in sunlight intensity through it's orbit. That's without any variations in cell efficiency at different temperatures, pointing issues, or long-term de

      • Re: (Score:3, Insightful)

        by Wandering Wombat ( 531833 )
        It doesn't need to provide thrust. Read the article. They need energy to keep the fuel warm.

    • Re:solar power? (Score:5, Funny)

      by inamorty ( 1227366 ) on Saturday June 14, 2008 @07:10PM (#23795331)
      No man, it's an attitude problem.

      it is now unable to even keep its attitude control fuel from freezing
      Instead of chilling out, it should apply itself more.

  • 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.
    • Come to think of it, it's even lasted longer than those Mars rovers.

      • Re:Not really as bad as the blurb sounds (Score:4, Funny)

        by Anonymous Coward on Saturday June 14, 2008 @04:52PM (#23794329)

        Come to google it, it's even lasted longer than those Mars rovers
        fixed.

        • Re: (Score:1, Interesting)

          by Anonymous Coward

          Come to google it, it's even lasted longer than those Mars rovers
          fixed.
          HAHAHA!

          But seriously, I think something floating about freely in space can survive more easily than something grinding around in dirt all day long. It's great that Ulysses lasted that long, but it's still not as astonishing as those Mars rovers, I'd think.

    • So long Energizer Bunny (Score:5, Funny)

      by dreamchaser ( 49529 ) on Saturday June 14, 2008 @04:34PM (#23794211) Homepage Journal
      those Mars rovers that just keep going and going

      I am waiting for Energizer to ditch that obnoxious rabbit and license the Mars Rovers for their advertising.
    • unless you compare to those Mars rovers that just keep going and going
      looking at nasa's site there don't seem to have been any updates on the rovers for about a fortnight (prior to that the updates seem to have been approximately weekly), I wonder if that is a bad sign.

      • Re: (Score:2)

        by chrish ( 4714 )
        IIRC they're hibernating during the Martian winter; I seem to recall reading an article about the controllers moving one into a good spot so it wouldn't run completely down during the darker months. This being /., I'm too lazy to go google it for you.

  • 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?

    • Let's home the satellite doesn't come back and find us messing about with the ISS.THEY did it! *points to Bush, Cheney, Rumsfeld and Rize*

    • Re: (Score:2, Insightful)

      by nfk ( 570056 )
      "the real (legendary) Ulysses"

      Hmm, so this probe is actually the real Ulysses.

    • Re: (Score:2, Interesting)

      by the_other_chewey ( 1119125 )
      As the Greek Geeks will know, the real (legendary) Ulysses (aka Odysseus) went on a ten-year odyssey returning home after the Trojan war.

      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. I never understood why this
      moron is considered a hero, and what the gods liked about the guy.

      • 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.

      • Actually, this is the archetype of a hero in western literature. Has something to do with how even religious people tend to view some of their Gods' demands.

        (As a religious person, I have spent my time complaining to God, myself.)

        One of the differences between religions is how much help the believer expects, and of what kind. This is definitely one of the concepts explored in Ulysses.
    • No, I read the Odyssey - it is on my book shelf, together with many other classics. Odysseus did give the goat herd a sucker punch that cracked a bone in his face (for good reason), and the rest of what you said is simply not true. The suitors attacked Odysseus and he fought them off successfully. I suggest that you read the book. It is in every library.

      • Re: (Score:3, Interesting)

        by gihan_ripper ( 785510 )
        Well, I don't know what version of the Odyssey you have, but I can quote from the Samuel Butler translation of Book XXII at the Project Gutenberg [gutenberg.org]

        As for Melanthius, they took him through the cloister into the inner court. There they cut off his nose and his ears; they drew out his vitals and gave them to the dogs raw, and then in their fury they cut off his hands and his feet.

        Here 'they' refers to Ulysses, Telemachus, and some cronies, as you'll find if you read further up the page. I can only imagine y

      • Odysseus did give the goat herd a sucker punch that cracked a bone in his face (for good reason), and the rest of what you said is simply not true

        You're thinking of Iros, the beggar, in book 18 (though we're told that he too was going to get the same punishment: 18.86-87). The punishment of Melanthios, the goatherd, is in book 22 (22.474-477). If it's any comfort the OP isn't wholly correct either, as it's not Odysseus himself who does the dismembering; the context makes it sound like it was his son, Telemachos, assisted by the "good" herdsmen. It's the bit just after Telemachos hangs a bunch of maidservants for having sex with the suitors.

    • Re: (Score:2, Insightful)

      by Tablizer ( 95088 )
      Ulysses cut off his nose and ears, pulled out his genitals for dog food, then sliced off his hands and feet.

      I find it humorous how ancient writers went into great detail about how torture was done. It makes them sound obsessed with violence. I wonder if that was the style, or whether its just that such info tends to survive longer?

      In 2500 years, will people be reading the same kinds of things about Guantanamo Bay and CIA water-boarding and think the same thing?
         

      • I find it humorous how ancient writers went into great detail about how torture was done.
        Thy weren't ancient writers, they were ancient storytellers. These stories were passed by word of mouth first, and the gory details tend to be the ones that stick in your memory and are easiest to retell.
    • So are we expecting the little tin can to come home and tell us about one-eyed aliens from a planet far away?

  • 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: (Score:3, Interesting)

      by endlessoul ( 741131 )
      The mods may have found this funny, but I find this interesting. Is it possible to modify the trajectory? Is it simply too far away to get to the sun? If the fuel already too frozen to be utilized?

      If it's going to be an orbiting piece of frozen metal, we may as well send it to a fiery and possibly information gathering demise.

      • Re: (Score:3, Informative)

        by PMBjornerud ( 947233 )
        "Attitude control" means the thrusters to change its orientation, as opposed to changing the course. You could likely make the probe spin real fast. Not sure if that would give you any more exciting data, though.

        I think you can safely assume the engineers on the project have gone through the possible options.

        • Re: (Score:2)

          by Fred_A ( 10934 )

          Not sure if that would give you any more exciting data, though.
          Dizzying data then, maybe ?

      • Re: (Score:3, Insightful)

        by mortonda ( 5175 )
        since it used a gravity assist to get into this orbit, I highly doubt it can in any way adjust its orbit enough to make it useful, unless another planet happens to stumble by... and since it intersects the orbital plane only twice per orbit, that's pretty bad odds too.

        Oh it will probably get to the sun eventually, if it doesn't run into something else, but it will be dead long before.

      • 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.)

      • Re: (Score:2)

        by Cecil ( 37810 )
        As with most problems in orbital mechanics, the problem is not the distance, but the speed it is travelling to maintain its orbit. In order to crash into the sun, it needs to reduce its speed from a very high number that maintains its orbit, to a very low number that allows it to crash into the sun without gaining so much speed due to gravity that it simply ends up in a newer, more elliptical orbit.

        I am certain that it doesn't have enough fuel onboard to change its speed by even a fraction of the required a

    • Re: (Score:1, Insightful)

      by Anonymous Coward
      I'd expect getting it to hit the sun anytime soon, would be a large delta-v maneuver, which it probably can't make anyway.
    • Yes, we could paint it black and have a really loud concert with terrible, terrible music!

      "Ship! Sun! Wham bang!"

      - RG>

  • 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.

    • Re: (Score:3, Insightful)

      by eggman9713 ( 714915 )
      It's just like they said in the Dilbert TV series, "credit travels up, blame travels down."

    • Re: (Score:1, Informative)

      by Anonymous Coward
      Except in this case it isn't even a NASA spacecraft, sure NASA lauched it and did lots of the science equipment, but the spacecraft itself was built by the ESA.
    • Where was it referred to as a "NASA spacecraft"? I looked over the summary and the press release, and it was always referred to as the "Ulysses spacecraft". The closest phrase was "The spacecraft was provided by ESA.", or references to the NASA/ESA "mission" or "project" not "spacecraft".

      It's an ESA spacecraft (built by "Dornier Systems, Germany (now Astrium)" [esa.int]), with a mix of US & European instruments, launched by NASA (shuttle + Boeing + McDonnell Douglas [wikipedia.org]), operated from NASA (JPL) by a joint NASA

    • 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.

      Umm. some of NASA's spacecraft are delivered to the agency in-orbit, after checkout. Until then, they remain the property of the contractor. This is the case with GLAST, which was just launched, but will remain with General Dynamics until L+60 days.

  • 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.

  • Why not closer orbit? (Score:1, Interesting)

    by Anonymous Coward
    Or crash it into the sun and take data as long as you can?

  • 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: (Score:3, Insightful)

      by Waffle Iron ( 339739 )

      but why not just equip them with a little more of the relevant isotope?

      Because then you'd need a bigger heavier radiator to keep the RTG from melting early in the mission.

      • I hadn't thought of that. I assumed it was just a case of adding another 1kg or so of whatever isotope is used. But actually, if you doubled the mass of RTG, and used an isotope with a longer half-life, you wouldn't need a larger radiator.

        • Re: (Score:3, Informative)

          by Free the Cowards ( 1280296 )
          And if wishes were horses we'd all be eating steak.

          It's easy to say things like, just double the mass of the RTG and just use an isotope with a longer half-life. It's much harder to actually find an isotope with that longer half life (the isotopes which have an appropriate half life and can be synthesized in the appropriate quantities, and to actually change the design of the spacecraft to accommodate the extra mass.

          It's an extremely complex engineering problem with a lot of tradeoffs involved. If they coul

      • what about.... (Score:2, Interesting)

        by ztcamper ( 1051960 )
        keeping active components of RTG at a distance and as they gradually decay bringing them closer together. Additionally a gradually increasing concentration of neutron reflective materials can be added as components get closer together. This would slow decay of radioactive materials and reduce temperature in the beginning potentially reducing size of radiators. This should also increase period of time for which RTG can be active by using variably reflective neutron mirrors.
        • Sounds like a wonderful idea for Dr Who or Star Trek technobabble - but RTG's work via radioactive decay, not via fission. These ideas won't work in the real world.

    • 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.

    • Re: (Score:2)

      by deblau ( 68023 )

      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?
      From Wikipedia [wikipedia.org], the best fuel to use is Pu-238 (as in, zomg Plutonium, atomic bombs). Read the article for the technical explanation.

      • Re: (Score:2)

        by dwye ( 1127395 )
        > From Wikipedia, the best fuel to use is Pu-238 (as in, zomg Plutonium, atomic bombs)

        No, fission uses Pu-239, not 238. Alas, I only know how to produce Pu-239 (oblig. bwah, hah, hah!) or I would write how different they are.

  • Mission's over? (Score:4, Insightful)

    by 192939495969798999 ( 58312 ) <[info] [at] [devinmoore.com]> on Saturday June 14, 2008 @05:58PM (#23794863) Homepage Journal
    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.

    • Re: (Score:3, Insightful)

      by Anonymous Coward
      The only problem with maintaining the mission is that the Deep Space Network has a limited capacity for data transfer, if the equipment is utilized to monitor the Ulysses, it can't receive data on other, more useful probes. My guess is that NASA, in order to allocate resources for missions still streaming huge amounts of valuable data, it's better to cut this one loose and focus on the others.
    • That's probably why it's expected to "end on or about July 1", rather than a hard-and-fast date.

  • I remember (Score:3, Interesting)

    by 32771 ( 906153 ) on Saturday June 14, 2008 @05:59PM (#23794881) Journal
    My astronomy teacher told us about it when I was still in school. Must have been around '92.

    She taught astronomy at the local observatory+planetarium. Her name was the German word for Fox so she had her own constellation = Vulpecula.

    Idiotically our local Christian democrat government canceled astronomy lessons in 2007. This used to be a required course for the 10th grade in Eastern Germany since 1959. (Its probably the money)

    Anyway, old satellites never die, and sometimes their orbits won't even decay.
  • Since it's built so well as to exceed expectations x4, why doesn't someone go get it, and bring it back for an refit/upgrade and a new mission?

    Worst case would be that it just looks damn good on someones front lawn.
  • This is great! The systems worked well up to the point until a fundamental limit, which could not be overcome, hits. The fact that they had overdimensioned it already that the system worked four times longer than planned shows that the right design decisions have been made.

  • 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.

  • The mainstream press will inevitably call this a rover.

Slashdot Top Deals

"Protozoa are small, and bacteria are small, but viruses are smaller than the both put together."

Close