Elon Musk, Future Defender of the Planet

The chance of asteroid YR4 hitting the Earth on December 22, 2032 keeps edging upwards, now approaching 2%.

An asteroid of up to 300 feet in diameter was discovered swinging by the Earth on December 27, 2024. It’s headed for deep space, but will be back in our vicinity on December 17, 2028 and then come quite close on December 22, 2032.

The initial estimate for YR4 gave it a 1.3% chance of hitting the Earth in 2032, with the impact of an 8 or 10 megaton nuclear weapon. An asteroid of that size is not a humanity killer (knock on wood), but it could cause a tsunami or, with bad luck, wipe out a city.

We’ve got a couple more months to observe it on this go-around before it disappears from view again until 2028, when it will swing by in December, 46 months from now. Hopefully, the more we learn about YR4’s orbit, the lower the chance of impact will become. Unfortunately, subsequent observations have raised the chance of impact to 1.6% and then this week to 1.8%, which is not a reassuring trend.

It would be prudent to be able to push it out of the way.

In 2022, NASA’s 1,100 pound Double Asteroid Redirection Test spacecraft hit a bigger (581 foot long) asteroid named Dimorphos (which circles a half-mile wide asteroid named Didymos) as a test of redirecting an asteroid. After a 10 month space voyage, the head-on collision was pretty successful because the couple of million pounds of material ejected from the impact crater slowed the asteroid more than predicted just from the spacecraft’s momentum. (Of course, we don’t know if we’d get the same bang for the buck with YR4 since we don’t know much about its geology or whatever you call the make-up of an asteroid. It’s probably the kind of stony-type that explodes in the atmosphere, but that can do a lot of damage like in Siberia in 1908.)

Wikipedia explains about DART:

For a hypothetical Earth-threatening body, even such a tiny change could be sufficient to mitigate or prevent an impact, if applied early enough. As the diameter of Earth is around 13,000 kilometers, a hypothetical asteroid impact could be avoided with as little of a shift as half of that (6,500 kilometers). A 2 cm/s velocity change accumulates to that distance in approximately 10 years.

And YR4 is considerably smaller than Dimorphos.

On the other hand, we don’t have ten years. If the chances of impact in 2032 don’t trend down this month and next, we ought to think about preparing to whomp it on its 2028 fly-by to give four years to push it off-path, plus more information about what it’s like. (E.g., would hitting it with a nuclear weapon be helpful, useless, or dangerous?)

The DART experiment cost a third of a billion dollars, so 3 DARTs would be a billion or so.

Fortunately, we have a lot more rocket power today than we did back in the 1990s when we made movies about this kind of menace, much of that due to the extraordinary entrepreneurship of Elon Musk.

That reminds me. I figure that it’s pretty inevitable that Donald Trump and Elon Musk, being two very big men, will eventually have a falling out and the President will fire his most important supporter. (I don’t see any evidence o that happening right now, but it just seems like the kind of thing to expect some day.)

Trump’s not usually really good at graciously kicking his underlings upstairs when they fall out of his favor, but Musk deserves better. So when Trump decides that the time has come for Musk to leave DOGE, allow me to suggest to the President that putting Musk in charge of Planetary Defense would be a right and fitting gesture.