By Phil Plait | October 13, 2011 7:00 am

In September 2011, I was honored to be on the speaker roster for TEDxBoulder, which is a local though independently-run version of the much-lauded TED talks. My talk was about saving the Earth from asteroid impacts, something I’ve spent a lot of time thinking and writing about.

The talk is online, and I’ve included it here:

The "We have a space program" line is from science fiction author Larry Niven, so I can’t take credit for it, though I modified it to add the "we can vote" bit. Also, this was the biggest audience I’ve ever spoken to, and it was a great crowd. I was almost last on the roster, but the audience was attentive and clearly enjoying themselves. It was a really fun, energizing, and mind-expanding evening.

The other talks that night are being put online as well. If you ever get a chance to attend a local TEDx conference, you should.

CATEGORIZED UNDER: Astronomy, DeathfromtheSkies!, Science

Comments (29)

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  1. Bob’s Junkmail, #222 « xpda | December 16, 2011
  1. don gisselbeck

    Would the current Republican leadership be willing to raise taxes if there was a high probability of a asteroid strike? I would bet no. They would just demand an end to Medicare.

  2. Ed Samson

    I’m going to go ahead and guess the author did not mean that he found the experience “enervating.” If it’s possible, please look up the word and change it.

  3. I am willing to be one those looking for asteroids just get me the equipment and small salary.
    Ghostbusters and Star Trek in one speech, I don’t think any of the other speakers could do that.

  4. ShaneC

    “Enervating” – I don’t think that word means what you think it means. ūüėČ

    Unless, of course, that’s what you really meant.

  5. Red shirt and black tie… If the astronomy thing ever goes bust you could get a job as a member of Kraftwerk.

  6. I really enjoyed your talk. You are a good speaker, and it was a fun topic. I appreciate knowing that smart people ARE studying this possibility and that there are ways we can avoid being destroyed like the dinosaurs. Thanks!

  7. hhEb09'1

    I’m with ShaneC, it should be “energizing”, enervating is the opposite.

  8. Hemogoblin

    Let me get this straight: nuking an asteroid is infeasible because the timing would be tricky, but actually hitting it or exactly matching velocities with it is easier? Can someone explain that to me?

    Before anyone says anything about “blowing up” asteroids, the idea behind nuking an asteroid is not to blow it up. Rather, the idea is that you set off a nuclear device at a distance from it – ablating a massive amount of material on one side of the asteroid which then pushes it off in the opposite direction (and besides the ablation, just the sheer radiation pressure will have a measurable effect).

    So the way I see it, nuking it has way larger margins: you pretty much only have to be on the right side of the asteroid within a couple of km and you can give it a good nudge, compared to the gravity tractor which requires finicky maneuvering and timing and – last but not least – equipment reliability we just can’t guarantee.

  9. Steve Ulven

    Excellent talk, Phil. I love it!

  10. Theron
  11. Hrmph. For some reason I typed enervate instead of energize. OK then, fixed. :)

    Hemoglobin (8): the problem is timing. You have to detonate a nuke, so you either have to match speeds with an asteroid, which is fuel-intensive, or blow it up with millisecond accuracy at just the right distance, which is very hard. It’s much easier just to aim for the rock and whack it. And at orbital speeds, the energy released is on a scale with nukes anyway!

  12. Hemogoblin

    Aha. Thanks!
    But that does sort of push it towards impactors rather than gravity tractors though, doesn’t it? Because the latter have the same delta-v problem as the nukes, except they also have to keep actively maneuvering working for a very long time.

    Full disclosure: part of the reason why I’m for nuking them is simply because it’s friggin’ cool. ūüėÄ
    (But I guess ramming them is pretty awesome too!)

  13. John Weiss

    Excellent and entertaining!

    I think, however, that a ‘gravity tractor’ would be less efficacious than popping off a nuke. Much less massive, so much less expensive.

  14. Grimbold

    “Come at me, bro!”

  15. Joseph G

    @12 Theron: Bahahaha. My favorite part:
    “We believe that the decisions of how to deal with the massive asteroid are best left to the individual,” King added.”

    Too true. Even Reagan is rolling over in his grave at what the GOP has become.

  16. konrad

    a couple of stupid questions: if we can hit an asteroid to change its orbit, is it possible that the chicxulub asteroid did the same to earth? (if not, how big would an asteroid capable of that have to be?) could it have had (or would such an impact have) any implications on our climate, or would any such change be so small as to be practically insignificant?

  17. If I ever won the world lottery, I know where I’m going to invest my money…I would want to have a second moon in planet earth!

  18. Great speech, but red shirt…as a Star Trek fan you should know better…

  19. WDM

    This speech was way too optimistic. Phil knows better, I know, because I read his book.

    But if I heard nothing more than what Phil said in this presentation, I would have left TED believing that NASA had the problem well in hand, and that there was really nothing to worry about.

    Nothing could be further from the truth. Assuming we don’t destroy the environment ourselves, we face _certain_ extinction (as a species) from an impact from space. Nothing we can conceive of would be of use in stopping an impact like Shoemaker-Levy 9, or any large comet, given that comets can come out of nowhere on highly elliptical orbits.

    People need to know and thus fear the truth, so that we can get all of our eggs out of this one basket.

  20. ?


  21. Titan

    Phil: Didn’t we put Dawn into orbit around Vesta? Surely we could do the same with a nuke.

  22. Hemogoblin

    @ 18. konrad

    a couple of stupid questions: if we can hit an asteroid to change its orbit, is it possible that the chicxulub asteroid did the same to earth? (if not, how big would an asteroid capable of that have to be?) could it have had (or would such an impact have) any implications on our climate, or would any such change be so small as to be practically insignificant?

    Every impact changes the Earth’s orbit ever so slightly, but the difference would be insignificant.
    First off, the difference in mass is… well… massive. :)
    The Chicxulub impactor is believed to have been a rocky (density of about 3000 kg/m^3) asteroid with a radius of roughly 5 km. The Earth has (thanks to its dense core) a mean density of about 5500 kg/m^3 and a mean radius of about 6000 km. Now remember: for spheres, mass scales with the cube of the radius!
    All in all, that makes for a mass ratio of more than a billion to one in the Earth’s favor.

    Second, our changing of the asteroids’ orbits is significant because all we care about is if they hit us or not. The Earth is a tiny, fast-moving (~30 km/s!) target in the vastness of space, so even a miniscule change in an asteroid’s velocity can mean the difference between a hit and a miss.

    However, for purposes of climate, the same change applied to the Earth would be entirely unmeasurable. The Earth has an elliptical orbit where the difference between aphelion (closest point to the sun) and perihelion (farthest point from the sun) is around 5 million km, but even that enormous change only results in a few percent change in insolation (received solar energy).

    EDIT: Arrgh, no <sup></sup> tags

  23. Yojimbo

    So – nobody is going for Phil and TED’s Excellent Adventure?

    [Sigh!] It must be my bas sens de l’humour

  24. slemke

    Great speech. I wonder if the current plans of NASA to land a person on an asteroid will yield any useful information that could help us in defending against an impact. I would hope that it would not be all for nothing. Another thought, if an oncoming asteroid could be nudged just a bit to get caught in the Moon’s gravity pull, then we could just let the asteroid hit the moon instead of us. It is our natural Dustbuster, anyway.

  25. That was excellent. The line about the space program coupled with your remark about voting is classic. I guess the laughter came about because of the recent political climate, no pun intended.

  26. Lisa Sample

    Considering the varied densities of these space bodies, I think the gravity leash would be safest. Some of the bodies in the asteroid belt aren’t solid, they’re a collection of smaller rocks held loosely together by gravity — a nuke hitting one of those would just scatter the rocks at best.

    I’m just glad none of the NEOs we’ve cataloged so far are the size of Vesta or Ceres… ūüėÄ


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