Incoming: The Chicxulub Impactor, Part 6 ― Now What? By Stephanie Osborn
In the last 600 million years, at least 3 large asteroids have impacted Earth, sufficient to generate craters of order 100km (60mi) across or greater. These are Chicxulub (in Yucatan, Mexico), Popigai (in Siberia, Russia), and Manicouagan (in Quebec, Canada).
Popigai Crater, Russia
Manicouagan Crater, Quebec, Canada
All three have been considered for the causes of mass extinctions.
As we saw last time, even older extinction events may have impactors as the cause. This includes the so-called “Great Dying,” the Permian-Triassic extinction event, which may relate to an unconfirmed impact crater in Wilkes Land, Antarctica.
There are many more very large structures and suspected structures that we may never know about, because of their locations―in the deep ocean basins, like the Eltanin iridium anomaly, three miles deep in the south Pacific basin off the tip of South America, discovered by core drilling. Or under the polar ice caps, like that Wilkes Land anomaly in Antarctica; the few places where rock outcrops can be seen in the Wilkes Land feature don’t display impact ejecta layers, which argues against the hypothesis. But the anomaly exists, and is still being debated.
What does all this mean?
It means that Chicxulub ISN’T unusual. It isn’t a one-of-a-kind event. It’s a semi-regular occurrence on geological timescales. It means figure out what to do NOW, while there’s time, because it IS gonna happen again. No “might.” No “maybe.” It WILL happen again.
If we let it.
The general consensus of the community is that a 60km (37mi) diameter impactor would “kill” Earth―would, as one of my favorite film characters noted, “wipe out all life on this little planet.”
The good news? That’s big enough for us to see it coming now.
The bad news? An asteroid doesn’t have to be a planet-killer to do a lot of damage.
What do I mean?
The Chelyabinsk bolide was only an estimated 20m (66ft) in diameter, and it was coming in at a very shallow angle to the ground. Had it come in at a steeper angle, closer to vertical, it would probably have hit the city and wiped it out. Even had it still detonated as an air blast, the shock wave would have come straight down, hit Chelyabinsk, and flattened it. This was “only” an estimated 600kt-equivalent explosion. Such an event is often called a city-killer.
And we never even saw the Chelyabinsk asteroid coming.
Speed, size, and reflectivity.
These things are very small as such things go―a few meters’ diameter―and they’re moving like a bat out of hell. The Chelyabinsk asteroid was moving at about 20km/s. In day-to-day terminology, that’s ~60,000-69,000km/hr (40,000-42,900mph)! They’re dark, dusty, and don’t reflect sunlight very well, and they have no light of their own. They’re durn near impossible to see. The usual method of detecting asteroids is to take long-exposure sky photographs and look for short streaks of light as the asteroid moves. But if it’s coming right AT you, it’s going to be a point of light, not a streak, indistinguishable from the background stars until it’s too late!
So assuming you SEE it coming, what do you do with it once you’ve found it?
Well, what you do NOT do―Hollywood notwithstanding―is blow it up with a nuke. That just turns it into a shotgun blast instead of a slug. Either will kill you.
What you DO…is move it. Just a nudge. It doesn’t really take that much.
Dr. Travis S. Taylor and I wrote in detail about this sort of thing in A New American Space Plan, and I do highly recommend checking out that book. But there are quite a few ways of moving an asteroid into a new orbit, some harder than others, some requiring a bit more advance warning, but all within our current levels of technology to accomplish.
The easiest is a game of interplanetary pool. Shoot a rocket at it, whose payload is a big dense hunk of rock or metal, on a precise trajectory designed to knock the thing into a known orbit that is NOT going to hit Earth―preferably into a non-Earth-crossing trajectory, though that might take a couple of shots to do. Of course, if it’s a rubble pile, that might just knock it to pieces and put us back in shotgun-blast territory.
So other options include nukes detonated ALONGSIDE, to nudge it; mounting a rocket engine directly on it; parallel the rocket engine alongside and use the exhaust to nudge it; attach a solar sail to it…you get the idea here. And I haven’t even exhausted the options yet.
But there are two gotchas: We have to know it’s coming, and we have to be able to get to it. If we don’t have those two things, well. It’s gonna get awfully messy, awfully fast.
And like I said, it IS coming. Sooner or later, astronomers are going to point and yell, “INCOMING!”
And we’d better be ready when that happens.
For more details, check out INCOMING! The Chicxulub Impactor by Stephanie Osborn on Kindleand Nook.
or alternately try out her fiction: Sherlock Holmes and the Mummy’s Curse.