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NASA Space Science

NASA Downgrades Asteroid-Earth Collision Risk 244

Posted by timothy
from the elephant-detector-working-fine dept.
coondoggie writes "NASA scientists have recalculated the path of a large asteroid known as Apophis and now say it has only a very slim chance of banging into Earth.. The Apophis asteroid is approximately the size of two-and-a-half football fields, and updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036 for Apophis has dropped from one-in-45,000 to about four-in-a million, NASA stated."
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NASA Downgrades Asteroid-Earth Collision Risk

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  • four in a million? (Score:5, Insightful)

    by Anonymous Coward on Wednesday October 07, 2009 @04:45PM (#29674305)

    Isn't four in a million the same as one in 250,000 ?

    • by palegray.net (1195047) <philip.paradisNO@SPAMpalegray.net> on Wednesday October 07, 2009 @04:47PM (#29674337) Homepage Journal
      No, it's the same as two in 500,000. Sheesh.
    • by wjsteele (255130) on Wednesday October 07, 2009 @04:47PM (#29674341)
      Nah... by the time it get's back to earth, the gravitational pull on it will break it into at least 4 pieces, each with a one in a million chance of impacting terra ferma.

      Bill
    • Re: (Score:2, Insightful)

      by RetroGeek (206522)

      Well yes, but "million" sounds more impressive.

      • by Anonymous Coward on Wednesday October 07, 2009 @05:50PM (#29675057)

        I am a programmer. I am paid to produce syntax not grammar. Deal with it.

        Sorry for the off-topic troll, but I really can't resist your signature. I'll answer your self-satisfied, pedantic quibble with one of my own.

        Programmers, unless they are creating new languages, do not produce syntax, they obey syntax [wikipedia.org]. Setting this point aside, maybe you meant, "I am paid to produce things which are syntactically correct, not things which are grammatically correct." Of course, you actually are paid to produce things that are grammatically [wikipedia.org] correct.

        Perhaps you meant, "I am paid to write in the highly precise, fascinating languages of computers and not the boring, ambiguous English language that my incompetent high school teachers made me hate." That might be true, but it probably isn't. Most programming jobs require quite a bit of written English, and the more grammatically correct it is, the better. Admittedly, this is usually less important than producing working code.

        Another possible reading: "I never quite understood English grammar, even though I felt like I should. I compensate by basing my fragile self image on excessive pride in my other skills and wearing a chip on my shoulder so people will be afraid to call me on it."

    • So the change was downgraded to 18% chance that the original value of 0.0022% was right.

    • by T Murphy (1054674)
      It's 4 in a million, and not 5 or 6. You don't get that resolution with 1 in 250000. Maybe they're just too lazy to divide by four, but precision might have been a consideration.
      • Re: (Score:3, Funny)

        by Spad (470073)

        So it's 1-in-250,000 instead of 1-in-200,000 or 1-in-166,666ish?

    • by migla (1099771)

      Isn't four in a million the same as one in 250,000 ?

      In this, statistical case, yes.

      • by migla (1099771)

        ...because of the million times we might have been hit, we only got hit four times i.e. one in 250k. (In other words: "I shouldn't have said statistical. I Should have gone to sleep."

  • Is it really that hard to use the same intial number for 2 ratios? I mean honestly... 1 in 250,000 is much easier to compare to 1 in 45k than 4 in 1million
    • Re: (Score:3, Insightful)

      by Aranykai (1053846)

      Yes, but can we get this in a real world equivalent. Something like 1200 words out of a library of congress?

  • Metric? (Score:5, Funny)

    by eggoeater (704775) on Wednesday October 07, 2009 @04:47PM (#29674349) Journal
    >two-and-a-half football fields
    So is that US football fields or are we using the metric system (ie. Soccer fields) ?
  • by RabidMoose (746680) on Wednesday October 07, 2009 @04:48PM (#29674365) Homepage
    How about 1 in 250,000?

    And "two football fields" doesn't tell us much about the thing's actual size. Besides "football" having two different meanings, one of which has multiple field sizes, what kind of volume are we looking at here?
    • Re: (Score:3, Informative)

      by olsmeister (1488789)
      Well, if you RTFA and look at the picture they've conveniently provided, you'll see that it looks like it is somewhere around 60-70 kilometers long.

      Apparently those are some pretty big football fields.

      • Well, if you RTFA and look at the picture they've conveniently provided, you'll see that it looks like it is somewhere around 60-70 kilometers long.

        Looks bigger than that in the picture.

        Of course, the text also said it was less than two football fields long, not two and a half football fields. Who writes this stuff?

        • Re: (Score:3, Informative)

          Who writes this stuff?

          And what are they drinking/smoking?

          The title and the picture don't match. From Wikipedia:

          "Based upon the observed brightness, Apophis' length was estimated at 450 metres (1,500 ft); a more refined estimate based on spectroscopic observations at NASA's Infrared Telescope Facility in Hawaii by Binzel, Rivkin, Bus, and Tokunaga (2005) is 350 metres (1,100 ft)."

          • Hmm. Let's ignore the scale line on the picture. Comparing that picture to other pictures of Apophis, I don't think that's even a picture of Apophis. Apophis is double-lobed, and this basically looks like an egg.

            Actually, come to that, it looks like Phobos. Scale is still off, Phobos isn't 60+ km across either, but that big crater is pretty distinctive.

    • And "two football fields" doesn't tell us much about the thing's actual size.

      Agreed. Why can't they use more useful units?
      For example, how many "Library of Congresses" is it?

    • Re: (Score:3, Insightful)

      by rossdee (243626)

      Yes, I get upset when they compare objects (where the important dimension is mass (weight) and maybe volume,) to something that is clearly a measure of area at best.

      Similarly hail should not be sized by coins.

      • I have to presume that we don't know the mass of the thing, since we don't know what it's made up of. I do agree, though, that mass and velocity are really the only two things that matter with an object like this. Squish/splash potential is key.
    • by gerddie (173963)

      Obviously they were talking about surface area, and the asteroid is shaped like here (start at timecode 1:14) [youtube.com]

    • by syousef (465911) on Wednesday October 07, 2009 @07:02PM (#29675731) Journal

      How about 1 in 250,000? And "two football fields" doesn't tell us much about the thing's actual size.

      You're translating from Jock to Geek. The Jock's understand a million as "a really big number" and 4 as a really small one. 250 is compleltely beyond them, let alone 250 times 1000! Football fields is a much more natural unit to them than a meter. Never mind that they're different sizes - they can all relate to being exhausted running the length of a football field. The concept of a meter just hurts their poor roid ridden brains.

    • by jrumney (197329)

      Besides "football" having two different meanings

      I know about Gaelic Football, but what is the other one? Surely Aussie rules doesn't count!

  • Uh oh... (Score:3, Insightful)

    by musefrog (1471169) on Wednesday October 07, 2009 @04:49PM (#29674369)
    They better be careful with those odds... that's dangerously close to a one-in-a-million chance, which everyone knows happen ALL THE TIME...!
    • by moon3 (1530265)
      By 2036 I will be dead already, along with bunch of other fellow aging Slashdotters, therefore I could not care less.
      • lets see... plus 1.... carry the 2.... equals.....uhhhh..... 57....

        oh shit... I will only be old.

        and we will all miss the slashdot 40th anaversery too!!! fuck!

        • make that:
          anniversary

          awww damn... I won't be able to post correct myself either!!!

          this world ending stuff just sucks.

    • by afxgrin (208686)

      Edward A. Murphy Jr [wikipedia.org] - smartest man who ever lived.

      As much as I hate his fucking law, it always becomes obviously true, time and time again.

  • Bad Economy (Score:5, Funny)

    by Ukab the Great (87152) on Wednesday October 07, 2009 @04:49PM (#29674377)

    Even the chance of an apocalypse is being downsized.

  • Dammit... (Score:5, Funny)

    by arkham6 (24514) on Wednesday October 07, 2009 @04:50PM (#29674385)
    I guess that means I'm still going to need to worry about the Y2k38 problem.
  • ... the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million, NASA stated.

    Can we keep our units/ratios consistent?

    ... the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about one-in-250,000, NASA stated.

    When you're regurgitating statistics that are generally considered good news - such as the decreased chance of global catastrophe - doesn't it seem reasonable to make those statistics int

  • Soothsaying (Score:3, Insightful)

    by ugen (93902) on Wednesday October 07, 2009 @04:54PM (#29674433)

    Clearly 4 in a *million* must be a very very small number, not like 1 in 250000 - which has thousands on the right-hand side, so that can't be good.

    In an attempt to make a new probability "less scary" the authors (or summary writers) also commit a specific error - there is only ONE asteroid so any probability related to it is ALWAYS 1 in something. It can never be 4 in something because there is only once chance of collision.

    • by aicrules (819392)
      I think they're implying that there are four universes. Perhaps Nasa has decided that for the sake of argument the multiverse is just four.
      • by pluther (647209)

        No, no that would be a million universes.

        Of which, the asteroid will strike Earth in four of them.

        There is a 1 in 250,000 chance, however, that anyone reading this will be in one of the four.

    • by Tanman (90298)

      ah-HA! But it's on an orbit!

      BOOYA!

      just kidding. Well, it is on an orbit, but I don't think the orbit will allow it to have more than one chance of hitting us within the given time frame.

  • one-in-45,000 to about four-in-a million.... um, they mean from 1-in-45k to 1-in-250k, but gosh darn it! They found a way to say "X in a million chance!"
  • Because Jack O'Neil's getting too old to stop those Goald asteriods.

  • Apophis? (Score:3, Funny)

    by DaFallus (805248) on Wednesday October 07, 2009 @05:02PM (#29674569)
    I thought we killed that asshole at the end of season 3?!
  • they crashed a $125 million orbiter into Mars because they mixed up metric and imperial units... so im not trusting their math ;)
  • by xednieht (1117791) on Wednesday October 07, 2009 @05:07PM (#29674639) Homepage
    We won't have to file taxes by April 15 in 2036, or possibly ever again. Death 1, Taxes 0.
  • People keep buying lottery tickets.

  • The real question is, will Bruce Willis still be alive and fit enough for an emergency space mission?

    Born: March 19, 1955. That will put him at 81 years old... We better freeze him now, so we can thaw him out in case of an impending asteroid strike.
  • NASA and risk... (Score:4, Interesting)

    by itedo (845220) on Wednesday October 07, 2009 @06:08PM (#29675265) Journal

    Taken from: http://en.wikipedia.org/wiki/Rogers_Commission [wikipedia.org]

    "Feynman was clearly disturbed by the fact that NASA management not only misunderstood this concept, but in fact inverted it by using a term denoting an extra level of safety to describe a part that was actually defective and unsafe. Feynman continued to investigate the lack of communication between NASA's management and its engineers, and was struck by management's claim that the risk of catastrophic malfunction on the shuttle was 1 in 10^5; i.e., 1 in 100,000. Feynman immediately realized that this claim was risible on its face; as he described, this assessment of risk would entail that NASA could expect to launch a shuttle every day for the next 274 years without an accident."

    Well, it has nothing to do with the topic, but I wouldn't trust a statement "four-in-a million" made by NASA... ;-)
    There is no guarantee for a secure life on this planet. Asteroid impacts are a part of the nature, so everybody should be aware of those risks...

    • by Nyeerrmm (940927) on Wednesday October 07, 2009 @07:00PM (#29675725)

      This kind of uncertainty is much easier to derive with fewer question marks than deriving the risk of catastrophic failure in a complex machine.

      Basically what this implies is that taking new measurements, we have an improved estimate of the position of the asteroid at the current time, and the risk of impact is taken by projecting those into the future using well known and tested dynamic estimation methods. Current uncertainty is easily defined as a 6x6 covariance matrix (for the 6 state variables), and this matrix can be determined using a good least-squares estimation method and published measurement numbers.

      In other words I give these numbers a lot more credence than risk numbers on the space shuttle. Theres a lot more science and lot fewer assumptions.

      Also I would be careful comparing practices in the huge human-spaceflight program, centered at JSC and KSC with those of smaller planetery exploration programs from places like JPL and Ames. They have amazingly different cultures and practices -- NASA is in no way a monolithic entity.

  • There are three objects with higher probability of impact on the list, two of them much larger than Apophis (270 m diameter). Their diameters are 560 m and 780 m.

    http://neo.jpl.nasa.gov/risk/ [nasa.gov]

    Scroll down to "Objects not recently observed"

  • I mean, the people who named the asteroid named it after Apophis in SG-1 because they were huge fans. Besides...by 2036, all we'll have to do is open a hyperspace window and send the asteroid through the planet. Just don't try to put a bomb on it, it will turn out to be made of naqadah and make an explosion equivalent to a supernova if that's tried. http://en.wikipedia.org/wiki/Naqahdah#Naqahdah [wikipedia.org]
    • by JSBiff (87824)

      Or, we could just mine all the naqadah out of it and use it to power generators. . . something the SGC completely failed to capitalize on. It seems like they are always looking for a source of naqadah, than when Apophis delivers it their doorstep, they just let it fly off into deep space. . .

  •     Two-and-a-half football fields? Does this include the stands and the parking lots? They couldn't give it to us in meters?

    • Two-and-a-half football fields? Does this include the stands and the parking lots?

      No, that'd be two football stadiums. This is just the fields. Plus one bitchin' tailgate party.

      They couldn't give it to us in meters?

      Big numbers fit bad in caveman brain. Big rock fall from sky, kill many mammoth. As many mammoth as fit on headball field. Lot of mammoth. Headball fun. Kick head of enemy caveman around. Mammoth get in way. New dead mammoth good, old dead mammoth bad. Smell bad. Worse than cave.

  • Wait for it...

    Wait for iiiiit...

    Waaaaiiit foooorrr iiiiit....

    No, missed!

  • by DynaSoar (714234) on Wednesday October 07, 2009 @11:38PM (#29677141) Journal

    Apophis had been downgraded to 4 chances in a million from 22 chances in a million. This new figure is clearly wrong, because it has 6 chances to impact between 2036 and 2103 (see http://neo.jpl.nasa.gov/risk/a99942.html [nasa.gov] ). Perhaps this means the actual metric is 6 chances per 1.5 million.

    Also of note in the upgraded data is the second of the 2068 near misses, having a 0.00 Earth radius distance. This is likely a statistical artifact caused by the fact that a near miss is a hit (a miss is a miss or it isn't; something that comes close but doesn't hit is a near hit).

    Since the distance is zero but the impact probability is 1.1e-07, they have almost certainly determined that it will pass by (and/or impact) almost perfectly edge on. Due to its size being equivalent to 2.5 football fields, and a football field being a 2 dimensional rectangle with no thickness, an edge on impact would have little effect, keeping all 510 megatons of impact energy confined within an area of 270 by 0.000... meters, ie. no area at all. Thus, the impact will have absolutely no effect unless you happen to be standing over that 270 by zero meter line when it comes down on you, or worse, up at you after having passed through the Earth (a zero thickness should be able to pass through the planet like a neutrino).

    Hopefully we will also get updated figures on 2007 VK184. It has a 340 in 1 million chance of impact. It gets 4 attempts between 2048 and 2057. Four chances in 9 years gives it 2.25 million years to have its one million attempts, in which time it will only hit Earth 340 times, or once every 2417095.5882352941176470588235294 days. This was calculated with due attention paid to leap years, though it is uncertain at the time of publication whether the frequent legislating of time standards by the US will result in the figure being in standard leap years or daylight savings leap years.

    Just to add a minor point of confusion, in case it has been so far missed: the question has been raised regarding the actual size of these objects, as 'football field' is ambiguous, there being two different kinds of 'football' using different size fields. The answer is that it doesn't matter. NASA has already proven themselves to be above and beyond the need for conversion factors, and so they need not differentiate between metric and non-metric football. In their usual excessively polite manner, Canada has repeatedly not pointed out that they too have 'football' similar to the US kind, but with yet another differently sized field. Their reticence is somewhat practical when one considers that fewer people watch Canadian football than watch curling, and nobody outside Canada watches that.

  • ...in which Michael Fish declared that the massive depression booting it across the Atlantic was /not/ a hurricane and was /not/ about to rip the UK a new arse.

    He was wrong.

  • While good news for sure.... science believes this was indirectly caused by universal climate change. Sigh...

    If we don't do something about solar helium production we're all doomed!

Always think of something new; this helps you forget your last rotten idea. -- Seth Frankel

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