Please create an account to participate in the Slashdot moderation system

 


Forgot your password?
Close
typodupeerror
×
Space Canada NASA United States

NASA: Satellite Debris Probably Hit Pacific, But Room For Doubt 65

Posted by timothy from the bring-your-finest-metal-detector dept.
An earlier report that debris from the recently deorbited UARS satellite had landed in Canada may have been premature. Apparently, the picture of when (and therefore where) the satellite deorbited is back to being clear as mud. Most likely, says NASA, the debris will never be found, but is thought to have landed in the Pacific Ocean. If you're an optimist interested in finding your very own piece of space debris, though, you might be interested in this map based on various re-entry scenarios (hat tip to Robert Woodcock); in the U.S., the Northwest is your best bet.
This discussion has been archived. No new comments can be posted.

NASA: Satellite Debris Probably Hit Pacific, But Room For Doubt More

NASA: Satellite Debris Probably Hit Pacific, But Room For Doubt

Comments Filter:

  • A clue to the location (Score:3, Funny)

    by Anonymous Coward on Sunday September 25, 2011 @02:28AM (#37506644)

    A whale with a serious headache thinks he knows where it came down.

    • Re: (Score:3, Funny)

      by Anonymous Coward

      Hole-in-one, eh?

  • Move along (Score:2, Funny)

    by Anonymous Coward
    Nothing to worry ab

  • Wrong planet. (Score:2, Offtopic)

    by ozmanjusri ( 601766 )
    Such a shame Schrödinger's crater is on the moon.
  • From what I understand, UARS was intentionally decommissioned and was instructed to perform a burn to (eventually) bring it down. But for the last few weeks we've had what appears to be zero useful clue about where it might land. I mean, speculations included at least 3 different continents and two oceans in a window of something like 12 hours, as recently as a couple days ago.

    Don't we have more deliberate and controlled ways to de-orbit satellites? Or is it just too complicated and expensive to add t

    • Re: (Score:2)

      by jhoegl ( 638955 )
      Yeah, I was thinking that too.

      It almost seems hyped, but the media would never do that, right?

    • Re:A little confused... (Score:5, Informative)

      by dutchwhizzman ( 817898 ) on Sunday September 25, 2011 @04:10AM (#37506850)
      From what I understand, they usually use the last fuel to put it into a clear and controlled descending orbit. For some reason, I think they ran out of fuel before they could do that on this particular satellite.

    • Re: (Score:2)

      by dbIII ( 701233 )
      It takes fuel to slow down with precision just as it does to speed up, and there wasn't any fuel. They call it "delta V" (change in velocity) for a reason instead of just talking in terms of velocity increases. Without fuel there's nothing to punch it through the atmosphere to a certain area instead of it skipping about those few degrees that make a difference between landing in Canada or the Indian Ocean.

    • Re:A little confused... (Score:5, Informative)

      by ygslash ( 893445 ) on Sunday September 25, 2011 @04:30AM (#37506892) Journal

      From what I understand, UARS was intentionally decommissioned and was instructed to perform a burn to (eventually) bring it down.

      Yes. When it was decommissioned several years ago, it used its last bit of fuel to bring it to a lower orbit so that it would come sooner.

      Don't we have more deliberate and controlled ways to de-orbit satellites?

      Yes. Nowadays, that is part of the mission planning for satellites. (Well, at least for NASA satellites...)

      Or is it just too complicated and expensive to add that kind of functionality considering the extreme odds of actually hitting anything valuable?

      That was the thinking in days when UARS was launched.

      Nowadays, even that tiny risk is considered important enough to justify controlled de-orbiting. Mainly for PR reasons, I think.

      In addition, we now realize that leaving dead satellites hanging around in a low orbit for a few years runs the additional risk of it colliding with something and causing an explosion of space junk.

      • > Nowadays, even that tiny risk is considered important enough to justify controlled de-orbiting. Mainly for PR reasons, I think.

        Hmm, tiny risk, but serious consequences. A large satellite piece landing in the center of a city is going to cause a lot of damage.

        • Re: (Score:2)

          by khallow ( 566160 )

          A large satellite piece landing in the center of a city is going to cause a lot of damage.

          An out of control car probably will do more damage. It's worth keeping in mind that even the large satellite pieces tend to be very fluffy. They might weigh hundreds of pounds, but they'll be coming down rather slowly.

        • Re: (Score:2)

          by sznupi ( 719324 )
          Not really. For a large piece - think a big piano, or (unavoidable analogy) a car, or maybe a loaded van being dropped from an aircraft at altitude (debris essentially falls at its terminal velocity when hitting surface). Yes, the day will suck for anything or anybody directly hit, or in the immediate vicinity; there's also a slight possibility of toxic propellants or such surviving the reentry. But I wouldn't really count it among "cause a lot of damage" even within city centres; don't expect anything real

          • Re: (Score:2)

            by lennier ( 44736 )

            Kinda how Zeus and his lightings are scary.

            Tell me about it. Stock standard recessed downlights with high-K fluorescent bulbs? Utterly pedestrian, darling. Get Athena to whip you up some kind of LED chandelier, she's good with the tech stuff.

    • Re: (Score:3, Interesting)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion

      • Re:A little confused... (Score:5, Informative)

        by Anonymous Coward on Sunday September 25, 2011 @05:44AM (#37507112)

        It takes a LOT of fuel to break orbit. To little and it will come back eventually. Why waste a buttload of fuel to lift all that extra fuel into orbit just so the satellite has enough fuel left so it can break orbit. It's much easier and cheaper to deorbit by bringing it down and letting gravity do the work.

        • Re: (Score:2)

          by Urkki ( 668283 )

          It's much easier and cheaper to deorbit by bringing it down and letting gravity do the work.

          Nitpick: letting air resistance do the work.

          With a bit of twisted thinking, gravity is actually the problem here! It's what keeps dead satellites in orbit, instead of letting them harmlessly escape into deep space.

      • Re:A little confused... (Score:5, Informative)

        by izomiac ( 815208 ) on Sunday September 25, 2011 @09:32AM (#37507830) Homepage
        Gravity at Earth's surface: 9.8 m/s^2
        Gravity at ISS: 9.1 m/s^2

        Satellites are still very much inside Earth's gravity well. They are not floating in space, they are constantly falling but their tangential velocity ensures they miss hitting the Earth.
        • Comment removed based on user account deletion

          • Re: (Score:1)

            by izomiac ( 815208 )
            To escape a gravity well you need a certain amount of energy per mass. On Earth's surface, it's 60MJ/kg. When you get to orbit you are a bit further away (gravitational pull declines asymptotically) so you only need 57 MJ/kg. That's what you need to get out of the hole. This is conservation of Energy, so there are no cheats to get around it. Otherwise we could deorbit and reorbit objects for free energy. Satellites would need to carry twenty times more fuel to deorbit.
            • Comment removed based on user account deletion

              • Re: (Score:1)

                by izomiac ( 815208 )

                But I'm not talking about free energy, I'm talking about using the energy of the earth to slingshot it out. Just like being on the end of a spinning whip you use the gravity of a partial fall to give you momentum followed by a burn out, like going downhill to pick up speed followed by gunning it to shoot up a hill.

                What you're trying to do is increase an object's gravitational potential energy without expending any significant amount of chemical potential energy or kinetic energy. This is not consistent with the law of conservation of energy. It would be akin to getting a 100 lbs dumbbell on your roof without lifting it.

                Here are some formulas. (M1 = mass of the Earth, M2 = mass of the satellite, r = altitude from center of Earth, v = speed of satellite, G = gravitational constant)

                Gravitational potential energy

      • Re: (Score:1)

        by eyenot ( 102141 )

        This is a great comment, BTW. I love how many times you say "dead birds". I'm not sure but I think you're saying that there are dead birds littering up outer space. Is that true? That's fucking atrocious! How the hell are they getting up there?!!?!?!?!?

        • Re: (Score:1)

          by izomiac ( 815208 )
          Ah yes, the Icarus birds. A tragic species, they often fly too high until the atmosphere is thin enough they asphyxiate. Thus, despite being able to fly twenty times faster than a peregrine falcon, they are in constant danger of extinction.

    • Re: (Score:1)

      by Askmum ( 1038780 )
      UARS made one orbit in less than 90 minutes, so if the de-orbit accuracy is 12 hours, then you have no clue at all where it will actually come down.

      It came down on its own, no assistance from de-orbit burns, the only thing stopping it was the drag from out atmosphere. And that tends to expand and contract rather erraticly due to external influences (like the sun) so it is very very very difficult to say when it would come down. Even in the last 8 hours the predictions of when it would come down were accu

  • So, nobody seems to be able to track the planned reentry of a big satellite in 2011...
    I guess then it is not too probable that governments have been tracking alien FTL spaceship visits since the 1940's, is it? ;)

    • What do you think all those neutrino detectors were being built for? It's how you track those FTL ships. Only the military didn't think the CERN people would figure it out as well.

    • Well, to be fair, a satellite in an extremely low Earth orbit with significant drag throughout its entire orbit is probably the most difficult place for us to track a live satellite.

      The atmosphere is unpredictable, so its constantly rephasing the orbit in ways you can't predict, and when its that low, a ground station has a very brief time to get acquisition, get some data, and send it to the controllers for orbit determination. Compare to a deep space vehicle (say Juno instead of an alien spaceship), wher

  • . . . would NASA really tell us where it landed, or would they want to recover it themselves?

    Mulder & Scully: "Where did the satellite land?"

    NASA: "Um . . . like . . . in the Himalayas, or somewhere . . . I dunno . . ."

    Hmmm . . . maybe I need to make a quick trip to Ice Station Zebra and snoop around . . .

    But if it really was a super secret squirrel satellite . . . we probably wouldn't have even known that it was coming down.

    • Re: (Score:1)

      by Anonymous Coward

      That video does NOT show UARS. It is footage of a series of Chinese lantern balloons. There is more of this deceptive stuff floating around on the internet - not every light in the sky is UARS!

    • Re: (Score:1)

      by Anonymous Coward

      That's a hoax upload, even the guy in the video said the wrong location and date.

      Read the comment from this other video for details:
      http://www.youtube.com/watch?v=gTVeOHiE_n4 [youtube.com]

  • I was hoping... (Score:3, Interesting)

    by jez9999 ( 618189 ) on Sunday September 25, 2011 @07:13AM (#37507304) Homepage Journal

    ... that it would land on Westboro Baptist Church. Can you imagine old Phelpsy doing a service and them BAM, the whole place is blown to smithereens by a stray solar panel? That would be sign of a just God if there were one...

  • NASA has an entire program office dedicated to tracking tens of thousands of pieces of orbital debris as small as 1cm: http://orbitaldebris.jsc.nasa.gov/measure/radar.html [nasa.gov]

    NORAD has a network of satellites and radar stations dedicated to finding incoming threats.

    But somehow, despite all this capability and despite tracking the descent of a 5,900 kilogram multi-meter by multi-meter satellite, they don't know where it hit.

    ?!?

    • It is a lot easier to track objects moving in a near frictionless environment than to track a object with unstable and constantly changing aerodynamic properties tumbling through the atmosphere.

  • I think NASA made up this story to cover a captured Goa'uld cargo ship that was being brought back to Earth.
  • We can put man on the moon, so they say. We can see to the edges of the universe, yet, NORAD can't detect nor track a satellite?
    Is this the beginning of another false flag?
  • I'm trying to figure out exactly who it was, but an amateur astronomer somewhere in South Africa called in to a radio talk show on Saturday indicating that he saw some debris burning up in the early hours of the morning. Trying to get a link up.
  • The Monge is an big scientific vessel from the French navy, conceived to track ICBM missiles during their re-entry phase and provide precise telemetry for validation purposes. Have a look there (in French) : http://www.meretmarine.com/article.cfm?id=117220 [meretmarine.com]

Slashdot Top Deals

Life is a whim of several billion cells to be you for a while.

Close