Paintballs may deflect an incoming asteroid

Tim O'Reilly tweeted about this proposal to deflect pesky asteroids on a collision course with earth. I'm reading The Last Policeman so this is even more interesting to me than usual.

In the event that a giant asteroid is headed toward Earth, you'd better hope that it's blindingly white. A brightly colored asteroid would reflect sunlight — and over time, this bouncing of photons off its surface could create enough of a force to push the asteroid off its course.

How might one encourage such a deflection? The answer, according to an MIT graduate student: with a volley or two of space-launched paintballs.

Paintballs may deflect an incoming asteroid


  1. In the video thumbnail there is a subtitle that says, “The second round would cover the the asteroid’s back side.”

    Even without reading any of the article I immediately assumed that it was legitimately about using paintballs to deflect an asteroid, but it wasn’t until I actually read the article that I realized paintballs to cover its back side would also be needed, and wouldn’t just be parting shots intended to remind that asteroid not to mess with us.

  2. cool. I guess they need somethin beyond what us mere earthlings use for paintballs though. Some paint that doesn’t freeze, cause that’s why nobody does paintball outside in sub-zero temps. Because Ouch.

    1. I’m not sure astroids feel pain, and I expect when launched by a rocket even frozen paintballs would explode on contact.

  3. This is completely silly, in that it requires finding the problem asteroid 20 years in advance, and being able to predict incredibly subtle variations in its movement. Given that at least half the near-earth asteroid misses haven’t been noticed until AFTER flying past us, and it’s extremely difficult to plot an asteroid’s path 20 years in the future with this level of accuracy, I can’t imagine we’ll reach the level of technology required to pull this off without coming up with much more powerful methods of diverting an asteroid’s course.

    1. Plus, you have to get that paintball out to an asteroid that is still 20 years away from the solar system.  Seems to me if you can do that, you’ve got warp drive and can likely employ any number of more effective strategies to divert it, including dropping heavy debris in its path to deflect its course (you don’t need much deflection when its that far away). 

      1. Once you paint the asteroid white, you can open a portal on it. From there, it’s a relatively trivial matter to have Bruce Willis blow it up.

      2. Plus, you have to get that paintball out to an asteroid that is still 20 years away from the solar system.

        No that bit is easy. Most of the threatening objects are likely to be in orbits which resonate with the Earth so there will be a string of close passes before the one which comes too close.

    1. Reflection gives you double the momentum of the reflected object. If the photon is absorbed you get the momentum at impact then other photons are re-radiated at lower energy, and carry away less momentum.

  4. I always thought the Crookes radiometer toy was pretty cool until I read that it stops functioning when the vacuum is compete enough. Something about this asteroid scheme smells like someone didn’t do the math.

    1. I think there may be some kind of misunderstanding there.  Unless by “complete enough” they meant devoid of photons as well as more conventional matter.  Otherwise, solar sails wouldn’t work either, and AFAIK theory has it that they should.

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