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Antarctic Craters Reveal Asteroid Strike

Posted by michael on from the rock-of-ages dept.

dhuff writes "Scientists using satellites have mapped huge craters under the Antarctic ice sheet caused by an asteroid as big as the one believed to have wiped out the dinosaurs 65m years ago."

10 of 234 comments (clear)

  1. Curious by ValiantSoul · · Score: 3, Interesting

    "One thing that did happen at exactly the same time was the reversing of the Earth's magnetic field." Darn so the water hasn't always drained the same direction? Does the magnetic field being reversed actually affect anything important?

    1. Re:Curious by oquigley · · Score: 5, Interesting

      The Earths Magnetic field keeps all kind of nasty radiation from hitting the surface.
      So it's always been a bit of a puzzle why there's no correllation between magnetic reversals (where the magnetic field weakens, fades, then reappears with swapped poles) and mass extinctions.
      After all, one would think that floods of radiation washing across the Earths surface would be unhealthy, no?

      But now it appears that when the magnetic field weakens, the solar wind induces a magnetic field in the ionosphere that's pretty much as effective at stopping high energy particles and cosmic rays as is the original field.

      Here's an article about it in New Scientist from a few months ago.
      New Scientist


  2. Well now... by reezle · · Score: 4, Interesting

    I'd like to think we could do something about this problem, but I wonder if any technology we have could alter the course of an asteroid large enough to be a problem. Do we even have a prototype of something like a fusion rocket that could potentialy move the hundreds (thousands/millions) of tons of mass that these big rocks have?

    Have the nuk-lear worryworts made sure that we haven't even researched the possibilities? Best I've ever seen is the occasional schematic of an orion-type starship from decades ago. Screw Ion-Drives. Let's give some money to the big engines...

    1. Re:Well now... by dyfet · · Score: 4, Interesting

      I believe this very question was seriously studied back in the late 60's and early 70's in project Icarus. I think their conclusion at the time was that the best option was to load up a Saturn V with as many nukes as possible, aim carefully, and just hope for the best...

    2. Re:Well now... by lommer · · Score: 4, Interesting

      Yes, they do have to be timed perfectly. However, in the nuclear explosion world, perfect timing is what it's all about. One of the primary difficulties in constructing a nuclear warhead is timing all the conventional explosives that compound the critical mass of plutonium (or uranium) to produce the nuclear explosion. The science is so precise that they have to account for the time delay it takes the electricity to travel down wires that are only meters long, let alone the rates at which the shockwave propagates through the conventional explosive - all of which must be correct to within thousandths of a second. Add another layer of complexity for hydrogen bombs.

      So yes, they would have to time them perfectly, but that wouldn't be too difficult as it's a problem they've already figure out how to solve when constructing the devices in the first place.

    3. Re:Well now... by jadavis · · Score: 4, Interesting

      Yup. Even an individual nuke requires very precise timing so that it implodes evenly. If not, it will start to break apart and never achieve the pressure required to detonate. Even when a nuke does detonate it only gets a moderate yield (I think "fat man" was about 15% yield) because it breaks itself apart so fast.

      --
      Social scientists are inspired by theories; scientists are humbled by facts.
  3. No layer of dust? by rde · · Score: 4, Interesting

    Quoth the good professor:
    The extraordinary thing about this meteor strike is that it appeared to do so little damage. Unlike the dinosaur strike there is no telltale layer of dust that demonstrates the history of the event.

    It ploughs through millions of tonnes of ice and snow, then leaves no layer of dust... d'you think it might have, I dunno, melted or something?

    More information at The Scotsman, btw.

  4. impact reversing magnetic field? doubtful by Lobachevsky · · Score: 5, Interesting

    I don't dispute Hans' rigor in studying the issue, but how can the correlation of the impact and the magnetic field reversing lead to the conclusion the impact caused the reversal?

    And why even compare this 780K yr old impact to what might've done the dinosaurs in 65m yrs ago? It just would confuse people with poor reading skills (*cough* slashdot readers) and lead them to associate this 780K yr old impact with the extinction of the dinasaurs.

    Also, the article attemps to explain why the 65m yr old impact would've caused climactic change whereas the 780k yr old impact would not -- I didn't quite understand their argument of why the older impact caused dust clouds leading to extinction while the newer impact did not -- was it because of the composition of ice vs rock?

  5. Homo Erectus was there by oquigley · · Score: 4, Interesting

    Wow! Only 780 thousand years ago?
    At that point our hominid ancestors were strolling around southern Africa. By then we had stone tools and the occasional use of fire. That's really recent in a hominid lineage that goes back, what 6 million years? They lived through a 3-7 kilometer asteroid impact! Can you imagine?
    Good thing it didn't land a few thousand miles to the north...

  6. Re:You really are missing something...... by davidsyes · · Score: 3, Interesting

    Or, was it just "a close shave"?

    Don't we pass through an asteroid belt about twice a year? I seem to remember something on Discovery Channel or on an astronomy site that named the belts. I'll revisit the sites, but in the meantime... Aren't there all sorts of odds (in favor of nature/against human populations) that could see us or the Earth being hit once in a while more frequently than we've recorded or claimed? If not, then...

    What are the chances (hi or lo) that we pass through some metallic or iced or similar matter that envelops or fries all the satellites in orbits? I'll concede that it MIGHT NOT happen in our lifetimes, but if it were GOING to happen by fluke or freak of nature, what kind of circumstances would be needed but not rip up large swaths of ground, and not rip away the breathable atmosphere?

    And, if we suffered such a "scrape", what would be needed to make orbital space unusable for say, 5 years, but, again, without the solar event tearing up the terra firma? Would passing through a sort of cometary corona or ice tail for about 6 or 7 days be enough? (And, let's assume or posit that no more than 20% of the the clean water and no more than 30% of the food production are affected.)

    Would anyone speculate on the confluence of events needed?

    David Syes

    --
    Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"