Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Space

NASA's HETE Coming Down 96

Posted by michael from the falling-down-on-new-jersey dept.
terrymr writes "NASA expects the High Energy Transient Experiment spacecraft which failed to successfully detach from the third stage of its launch rocket in 1996 to fall to earth within the next few days. While most of the spacecraft will likely burn up in the upper atmosphere there is a good chance that the spacecraft's batteries (weighing 33lbs each) may reach the ground intact. Current predictions put re-entry at 4:41 EDT Sunday April 7 (+/- two days)."
This discussion has been archived. No new comments can be posted.

NASA's HETE Coming Down More

NASA's HETE Coming Down

Comments Filter:
  • Before the sky falls. Anyone might perish under the batteries crashing down. Live your life to the fullest before you no longer habe the change.

    • hehe (Score:1)

      by altaic ( 559466 )
      Too early... that's supposed to read "have the chance" at the end. I think I'm going to sleep those days away.
  • They would have kept going, and going, and going...

    They must'a used these [radioshack.com] instead...

    -RickTheWizKid
    • Well, actually ...


      The HETE batteries *are* Energizers! The cells are cordless screwdriver size (2/3 C) rapid charge NiCd cells, 23 cells to a battery. There are six batteries in three *aluminum* cases.


      HETE is a low cost mission. The HETE spacecraft were built mostly from off the shelf commercial parts, not high cost aerospace parts. The commercial NiCd cells have actually proved very robust and reliable in space: the batteries on HETE-2 have gone through about 8000 discharge cycles so far and are still holding a charge just fine. The HETE-1 batteries could not be charged after the rocket's failure to fire its pyros left HETE-1 in the dark inside the DPAF can. Can't charge batteries without energy.


      The press release is a bit confused: I believe the stainless steel batteries must be in SAC-B. There is very little stainless steel in HETE: there are no large refractory parts at all.

  • Ebay... (Score:3, Funny)

    by pfb ( 201727 ) on Saturday April 06, 2002 @07:10AM (#3294902)
    /me wonders whether items will appear on ebay before they even land...
  • Hmm..anyone care to explain that?

    • Re:They´ve got minute-exact time, but +/- 2 days? (Score:2, Informative)

      by Anonymous Coward
      They calculated average time of the entering with 2 days of standard deviation.

      Do you remember math?

      • > Do you remember math?

        Do you? The precision given in an estimate should not be greater than the precision in the error bounds.

        A meaningful estimate would be "Sunday, +/- 2 days".

        The extra detail of "4:41 EDT" is meaningless, due to the magnitude of the error bounds, and only serves to give the illusion of precision where none exists - probably to sate the anger of the masses who don't comprehend the magnitude of the problem, and therefore don't understand why a multi billion US$ space program can't predict when something they launched will fall out of the sky.

        Russ %-)
    • either that's a really silly (but technically valid) way of describing the error margin, or possibly, (and this is pure conjecture : I ain't no rocket scientist) the spacejunk can only enter the atmosphere in certain angles/orbits/what-have-you. So it can only get thru at a certain point in its orbit, equating to a particular time of day. give or take a few days
  • Does anyone know how to bring this up with NASA's tracking program [nasa.gov]?

  • reminds me of skylab (Score:3, Funny)

    by serps ( 517783 ) on Saturday April 06, 2002 @07:12AM (#3294907) Homepage

    Reminds me of when Skylab [nasa.gov] fell to earth, dumping pieces of itself over Western Australia. The local president of the town council, Mervin Andre, gave the Director of NASA a littering ticket [amristar.com.au] when chunks of the disintegrating space station dropped over the area southeast of Perth. The ticket remains unpaid to this day, although the council later waived the fine anyway.

  • What are the chances of this hitting somebody? People say the chances are slim to nill, and just recently a significant piece of equipment came down and I didn't here about anyone getting hit. But a couple years ago NASA printed an article [cosmiverse.com] that the odds of someone being hit by the falling Iridium debris were about 1 in 250. By my count, this is the third potentially hazardous satellite entry in as many years, leading me to believe that eventually, someone will be hit.
    • Getting hit on the head with satellite debris certainly would be something to forget to tell your grandchildren about....
    • Actually, the chance of somebody actually getting hitby any given battery (if we were all distributed equally around the planet -- oceans and all) is 1 in 176949. (Assuming the average person displays about a square foot of target area from above.) But the chance of a battery landing within 10 feet of them (which is probably nearly as bad) is 1 in 563.

      However, since most of the world's population lives in urban environments, and since 70% of the earth is covered with water, the chances decrease, uh, astronomically.

  • The HETE-1 was supposed to look for gamma ray bursts. If you haven't heard about these events, they are believed to emanate from explosions so powerful that they produce more energy in a matter of seconds than the sun will emit in its entire 10 billion years of life.

    The cool thing is that astronomers have almost no idea what could be causing these enormous bursts.

    Check out http://www.sciam.com/0797issue/0797fishman.html [sciam.com] for more information.
    • ... astronomers have almost no idea what could be causing these enormous bursts.
      Actually, they have. Scientists from Leicester University analyzed the spectral fingerprint of a GRB and they found that it had come from a Supernova explosion. There's an article [nature.com] in the current issue of Nature [nature.com]. The interesting part is that the GRB occured 10 to 100 hours after the Supernova explosion.
  • ... the spacecraft's batteries (weighing 33lbs each) ...
    From the article:
    ... four small stainless-steel batteries, weighing a total of 15 kilograms (33 pounds) will survive re-entry.
    So each battery weighs 3.75 kg. Hmm, I just wonder what kind of batteries those are ...
  • Does it concern anyone else that a 2-day window is awfully large? That means even the us space command can't really pinpoint where this thing will come down, even though it's our own junk. Kinda makes you wonder how it would go if a meteor, etc got too close...
    Sir_Haxalot
    • Kinda makes you wonder how it would go if a meteor, etc got too close...

      Well, I'm really glad this one [cnn.com] is going to come in 900 years. If it was to hit next year it would've probably wiped the human race. Unfortunately, hollywood and bruce willis are not enough for this kind of threat.
      • dude, to stop a meteor all we hafto do is launch to tripped out shuttles (obviously made of plastic) at the same time and land on the meteor and drill, then plant a nuke. duhh

        alternative would be to send dig-dug up there, he knows what to do!
    • A meteor is actually easier to predict. A meteor will be coming in from an orbit that crosses the path of earth, so it will come almost straight at earth. A satellite is orbiting earth and slowly dipping into the atmosphere. It's the interaction with the atmosphere that makes a satellite fall unpredictable. It will last for days or weeks, as opposed to a meteor, which will come straight in.

  • I hope.. (Score:1, Troll)

    by inburito ( 89603 )
    ..it will land in USA, King County, ZIP-code 98052-6399 and create a huge explosion.
  • how can they give the TIME of the event when they are not even sure about the DAY?

  • Precision, precision. (Score:4, Funny)

    by ChiPHeaD23 ( 147491 ) on Saturday April 06, 2002 @07:57AM (#3294974) Homepage
    'Current predictions put re-entry at 4:41 EDT Sunday April 7 (+/- two days)'

    Guess somebody's getting a little too specific in their "predictions" given their precision. In other news, today's high will be 67.2 degrees (+/-40).

    • A typical way of doing these calculations would be to calculate everything to the nth decimal, then do a separate calculation to figure out uncertainty. The exact calculation goes down to a minute. The uncertainty is about two days.

      The uncertainty is due to atmospheric density differences at high altitudes and uncertainty in drag due to spacecraft orientation.

      Then again, I'm a nuclear engineer. What do I know about Rocket Science?
      • If anybody at NASA had said "It'll hit the ground on April 7th, give or take 2 days," people would have been all over them for being so imprecise. By saying "4:41 EDT," they somehow give credibility to their claim, regardless of whether or not they had made any calculations.

        Similarly, if a high school student had made such a prediction relating to, say, the next time he'd get play from the girl down the street by saying "It will happen at 7:56 PM, April 21, 2002. Give or take a few weeks," it would mean absolutely nothing. The exact time does not matter when even the date is in question.
    • Must have been one of my lab students.
  • Yesterday I read that an asteriod had a 1 in 300 chance of hitting earth in [b]900[/b] years time.

    Yet they cant determine how soon that satellite is going to hit which is exponentially sooner.

    • That is almost certainly because the satellite is grazing the atmosphere at a very shallow angle. When satellites, and for that matter space shuttles, reenter the atmosphere deliberately, the reentry is made a little steeper, which allows for accurate predictions of when and where it will reenter. With very shallow reentry angles, even the slight day to day variation in the "height" of the upper fringes of the atmosphere will change when and where the reentry will occur.

  • I was astounded when I read that "nearly 3,000 satellites and spacecraft now in orbit around Earth" in CNN's coverage [cnn.com] of the story. I wonder if they are counting space junk? It seems like a huge number. With so many in the sky, it is a wonder there is not knews of this sort every day. There was another uncontrolled decent [cnn.com] in January of a Nasa satellite. I liked this quote: "Orbital debris has never been known to injure a human, but legend has it a chunk of Skylab brought an untimely end to an Australian cow."
  • You know, I actually tried to work out the force of impact of one of the batteries, but then I realized: who actually would give a crap? It's gonna hit, and it's gonna make a really big thud.

    I just hope nobody ends up in the way, or it'll turn out to be a big splat.

  • Too much space junk (Score:3, Funny)

    by somaroma ( 250278 ) on Saturday April 06, 2002 @08:43AM (#3295046) Homepage
    With all the space junk in orbit now, I wonder if the reason we have not be been contacted by aliens isn't because we are the bad neighbors in the milkyway. We are like the people on the street with uncut grass and old broken down crap strewn all around our yard. Nobody wants to come over and say hello because they assume the residents are low lifes. If we do get a visit, it may be the head of the galaxy association telling us to take down the tacky mood decorations and clean the junk out of our space.
    • Wired had an article last month talking about a laser that could be used for both missle defense and to zap pieces of space junk into oblivion

      Sounds Kinda interesting. Remember in that star trek movie, #3 or #4 where they had the Klingon going around shooting up space junk. He shot that satelite with tribal pictures painted on it. Maybe we will be doing that someday

    • We are like the people on the street with uncut grass and old broken down crap strewn all around our yard. Nobody wants to come over and say hello because they assume the residents are low lifes. If we do get a visit, it may be the head of the galaxy association telling us to take down the tacky mood decorations and clean the junk out of our space.

      Or not. Judging from my experience when I leave old junked cars and major appliances in my front yard, it's a great way to make new friends and the encounter would go more like this:

      Interstellar pickup truck with interstellar Confederate flag comes up to the edge of our debris field. Occupant gets out, picks his way gingerly down to the surface, knocks on International Space Agency's door.

      "Hi there. I wuz just drivin' by, and I was wundrin, is y'all still usin' that there Iridium system you'se've got still orbitin' yer planet? I got sompin' like it at home and I need some parts. Kin I take it off'n yer hands fer a coupla cases of beer? Thank-ye kindly."

  • Let me get this straight, on March 16, 2880, we will get hit by an asteroid. But they can only manage to place this in the next 4 or 5 days?

    I guess physics isn't an exact science.

    • Re:+/- two days? (Score:2, Informative)

      by hacksoncode ( 239847 )
      The key to when a satellite deorbits is when the atmospheric drag causes it to. The atmosphere expands and contracts based on a variety of factors including solar flux, which is very hard to predict. This isn't physics, it's astro-meteorology (multiple puns intended).

      By comparison, figuring out when an asteroid will hit the earth is a simple matter of determining it's path and speed and doing a simple calculation.

  • ... for every slashdotter if a part of this falls on the beer can I have placed outside in my garden. not_cub

  • 33 pounds TOTAL, not each (Score:5, Informative)

    by wowbagger ( 69688 ) on Saturday April 06, 2002 @10:23AM (#3295249) Homepage Journal

    Initial analysis indicates that only four small stainless-steel batteries, weighing a total of 15 kilograms (33 pounds) will survive re-entry.


    In other words, the weight of all 4 batteries is 15 kilos, not the weight of each battery. Still, 3.5 kilos at terminal velocity is nothing to sneeze at - perhaps I should buy a large number of pillows from Yahoo!....

  • "...there is a good chance that the spacecraft's batteries (weighing 33lbs each) may reach the ground intact."

    So...when should I expect it to land on my car?


  • 'Stainless steel batteries? ' I think not. More likely that they are plutonium or some other nuclear material, and the reason that no predictions are being made about where they will land is because NASA doesn't want to start a panic. As I understand it they are designed to burn up on re-entry to avoid ground level contamination (that says nothing of atmospheric contamination along the flight path). If they survive all the way to the ground and they are radiological....

    Space Nuclear Power Systems [nuclear.gov]

    Space Nuclear Power System Accidents [nasa.gov]

    Bulletin of Atomic Scientists: How many nuclear devices are there in space? [bullatomsci.org]

    Link to CNN story [cnn.com].

    • As far as I know, in recent years, ie the 90s, NASA has only used plutonium decay reactors for missions that go past mars, where solar panels are ineffective. Also, if memory serves, the launching of nuclear reactors is forbidden on the global level these days...... Thats why when NASA has been dumping lots of money into things like impulse drive as of recent.

    • Umm... why was this modded up? This is just plain ridiculous, and the person posting has no idea what he/she is talking about. NASA only puts nuclear power cells on probes that are headed to deep space, where the light from the sun is too weak to use solar power. No NASA satellite in orbit around the earth uses nuclear power, period. It is just too big of a hassle compared to the ease of solar panels and batteries.

      And again, the reason that the prediction is vague is because the satellite is reentering the atmosphere at a very shallow angle. This makes it impossible to accurately predict when, and therefore where, the satellite will reenter.

    • Nothing nuclear here. These are NiCad. (Score:4, Informative)

      by Christopher Thomas ( 11717 ) on Saturday April 06, 2002 @12:26PM (#3295643)
      'Stainless steel batteries? ' I think not. More likely that they are plutonium or some other nuclear material

      Um, you might want to actually read about the satellite before assuming it uses radiothermal generators.

      The great big solar panels in the picture of the satellite might have been a hint that it didn't use nuclear power.

      From the HETE pages (describing HETE-2, an exact duplicate of the HETE-1 craft whose launch was unsuccessful):

      The HETE-2 power system hardware consists of

      • four solar panels, made of honeycomb aluminum with silicon substrate, each supplying 42W.
      • power box with power point tracker,~90% efficient
      • 6 battery packs, each made up of a string of 24 1.5V NiCd cells, and each with 1.2 A-hrs capacity


      You can find more information on the specs of the HETE satellites at http://space.mit.edu/HETE/spacecraft.html [mit.edu].
    • You're a moron.

      I saw a show that talked about the HETE a few weeks ago. They were pissed that it was being put on a pegasus, since the rocket had a 50% failure rate or so. It seems unlikely that they would have put a nuclear battery on such a launch.

      Also, if you read the article, you would have noticed that the battery died after a few days of being stuck inside the launch vehicle. Doesn't sound like a radioactive battery to me.

      Finally, there are solar panels on the experiment. It would not make sense to have both a plutonium battery and solar panels on the same sattelite.

    • Sorry to resort to trollspeak, but it's the only language adequate to describe your laziness, arrogance, and stupidity.

      Here's why I'm making a point of insulting you. Nuclear power of all kinds is backed by a lobby of smug, short-sighted techno-fetishists who just love it in when some hippie does the usual misinformed kneejerk antinuke rant. This allows them to portray all their opponents as such, and avoid the serious issues nuclear technology raise. You just scored one for their side!

      All you had to do was make a quick search on Google, which would have led you straight to the specs for the spacecraft in question [mit.edu]. Which would have told you that the HETE is powered by a combo of solar cells and nicads.

      (Of course, nicads are also an environmental problem, but at least the ones on HETE aren't going into a landfill. Good environmentalist that you are, I hope you take your used nicads to a toxic waste depot. Or is pollution always somebody else's fault?)

      Next time you feel inclined to speak up for The Cause, make sure you're actually serving The Cause, and not your own pathetic ego.


  • Where's the Taco Bell Target sitting for this one?
  • The question now is will Taco Bell put another big bulls-eye out in the general area and offer free tacos to the world if it gets hit again?

  • A couple things (Score:2, Informative)

    by LupusUF ( 512364 )
    People keep asking why they don't know when it will hit"

    "The re-entry is uncontrolled, and due to potential solar flux variations, time and location predictions will not be reliable until only a few hours before the re-entry event," said Scott Hull"

    And contrary to what the original post says, the batteries are not 33 pounds each. That is the total weight of all of them.

    Initial analysis indicates that only four small stainless-steel batteries, weighing a total of 15 kilograms (33 pounds) will survive re-entry."
  • Anyone know the predicted area of landing? I'm sure a general idea can be had based on current orbit...
  • there is a good chance that the spacecraft's batteries (weighing 33lbs each) may reach the ground intact

    If I'm lucky I won't have to buy that extra laptop battery...
  • Well, there's our tax dollars at work. Can I get a nice big OOPS??
  • With all of that orbiting space junk out there, why not salvage it? It seems to me an awful waste to just burn it up in the atmosphere, especially when the average bird is on the order of US$150M.
  • Here a link to the text of the Bavarian state-owned news channel that reports mysterious lightning effects yesterday evening in Southern Bavaria around Munich, Germany:

    http://www.br-online.de/news/aktuell/ [br-online.de]
    (Look for "Mysteriöse Lichterscheinungen über Südbayern - Weltraummüll?")

    And for convenience the Babelfish translation (since the original is not linkable):

    "Mysterious lightning effects over Southern Bavaria - Space debris?

    Munich: In the sky over South Bavaria it gave several fire balls and optical phenomena yesterday evening. Hundreds anxious humans addressed themselves to the police. Particularly in the region "Bayerischer Wald" and Garmisch as well as in Munich long lightning effects were to be seen around 22:30 for several seconds. Pilots of airliners and military jets announced similar observations over radio. There are no reports about injuries or damages. The space authority NASA had announced that on weekend space garbage over Central Europe could fall. Yesterday it could not yet acknowledge a connection with these optical phenomena however."
  • Anyone notice the update to the annoucement. Looks like it re-entered above China. As if our relationship with them isn't shaky enough.....here's a satalite for ya!

Slashdot Top Deals

Put your Nose to the Grindstone! -- Amalgamated Plastic Surgeons and Toolmakers, Ltd.

Close