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Artist's conception of asteroid 2012 DA14 passing through the Earth-moon system on Feb. 15, 2013. (NASA/JPL-Caltech)

“Vermin of the Skies”

The JPL scientist in charge of tracking incoming asteroids tells us if we should be worried.

Going back to potentially dangerous near-Earth objects, you write that we’ve started to look for these at the same time that, thankfully, we’ve developed the kind of technologies that could save us should we find one coming our direction. How might we be able to save ourselves from impact?

The key is: find them early, find them early, and find them early. If you find them 10, 20, 30 years prior to a predicted Earth impact, then you do have time to deal with them. So let’s say we find an object that’s 100 meters in diameter that’s predicted to hit the Earth 20 years down the road, then the easiest and simplest [solution] would be to simply run into it with a spacecraft.  We demonstrated the navigational technology to do that when the Deep Impact mission purposely ran into Temple 1 on July 4, 2005. Just run into it, slow it down a millimeter per second or two, change its orbital period so that in 20 years time when it was predicted to hit the Earth it would miss by a wide margin. There have been other techniques discussed, everything from a so-called gravity tractor, which is just too wimpy to be a primary deflection device, to paintballs which is cute and colorful, but just nonsense.

Is that the method of putting paint on one side in order to change its reflectiveness, and that would sort of push it a little bit in some direction?

It would change the orbital dynamics of the object just a little tiny bit, but it’s really just ridiculous. I would take the spacecraft carrying these paintballs and run the entire spacecraft into the asteroid [laughs]. There are some other techniques – a solar reflector, a solar sail, laser ablation techniques – but some of these are far more complex, require far more sophisticated engineering. It’s the old principle of KISS: Keep It Simple Stupid. Just do the simplest and easiest technique that works and that would be just running into it with a spacecraft.

In a footnote toward the end of the book you mention that President George W. Bush’s press secretary got an email in 2008 with the subject line, “HEADS UP,” about an asteroid headed towards Sudan. The scientist suggested that the administration warn the Sudanese, but no one did because the U.S. had no formal relations with them. This seems particularly interesting when you write in a later chapter that some body like the United Nations should have an internationally approved plan at the ready. How likely do you think it is that they can all get together and agree on something?

In a couple of weeks I’m leaving for Vienna, where the United Nations Committee on the Peaceful Uses of Outer Space is meeting, and that’s what we’re going to talk about: getting an international plan in place and accepted by the United Nations so that when an object is found on an Earth-impact trajectory, there will be an international agreement that says “this space-faring nation would be charged with deflecting this object for the benefit of the others,” or something like that. The protocols and guidelines have not yet been written, but they are being discussed and hopefully they will be written in not too long, so we won’t have to start this process after we find an object.

There aren’t that many space-faring nations, and it seems like there are endless possibilities for last-minute negotiations -- for example, what if it’s going to hit a region with which the elected asteroid-deflecting nation is at war?

It’s very interesting, and the space lawyers will have to get involved. If the deflection is unsuccessful and it was to hit in Europe, but the deflection didn’t quite make it and now it’s going to hit in the United States: that’s the so-called Deflection Dilemma. You can’t just blast [the asteroid] off the surface of the Earth, it moves slowly from the impact site across the Earth, and then off the edge of the Earth, if you’re successful. But there is a chance you would move the impact point from one country to another if your deflection attempt was not successful.

You wrote that “human exploration is usually driven not by the quest for knowledge but for commercial gain.” Does that mean you support asteroid mining?

It’s not something that would be commercially viable right now, but these objects are rich in platinum group elements. They’re rich in iron and nickel, they’re rich in ices – water ices and hydrated minerals – so they could be processed for water, and water can be broken down into hydrogen and oxygen, which is rocket fuel. You wouldn’t go out and mine these materials to bring them back to Earth – that just wouldn’t be a good business model, because you could do it cheaper with minerals here on Earth. But as launch costs decrease and the pockets of platinum group elements and others that we now have on the Earth’s surface get less and less, it might one day make sense to mine this material and bring it back to Earth.  But it would probably make more sense if you’re going to build structures in space. If you’re going to build outposts in space then you’re going to have to look around for resources in space, you’re not going to build structures on the surface of the Earth and then launch them. It’s just too expensive. You’re going to build watering holes and fueling stations full of water, and then you’d like to take advantage of these natural resources that are already there.

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