Before the sun dies, we are likely to be struck by about ten asteroids that can return us to the Permian Era–or worse. What to do? The opening of “Deflecting Asteroids,” Gregory L. Matloff’s IEEE Spectrum piece:

“In early 2007, I took part in a NASA Marshall Space Flight Center study of proposed deflection techniques that could be ready for use by the end of 2020. My colleagues and I assumed that by that point we’d have a heavy-lift booster capable of sending 50 000 kg or more on an Earth-escape trajectory.

We considered several strategies. The most dramatic—and the favorite of Hollywood special-effects experts—is the nuclear option. Just load up the rocket with a bunch of thermonuclear bombs, aim carefully, and light the fuse when the spacecraft approaches the target. What could be simpler? The blast would blow off enough material to alter the trajectory of the body, nudging it into an orbit that wouldn’t intersect Earth.

But what if the target is brittle? The object might then fragment, and instead of one large body targeting Earth, there could be several rocks—now highly radioactive—headed our way. Also, a lot of people might object to even the mere testing of any plan that involved lobbing 100-megaton bombs into space. The nuclear option might then be limited to a last-ditch defense of Earth, should we get little warning of an impending impact.”

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Future scientists in training, 1979: