Tracking space rocks
And other existential threats
One leading theory for how life on Earth started is known as the giant-impact hypothesis. The idea is that, sometime around the formation of our solar system, an object named Theia, roughly the size of Mars, smashed into the still-forming Earth. The massive collision embedded material from Theia into Earth — including organic matter that became the building blocks of life — but also spewed off a huge amount of debris, which collected in orbit and, eventually, coalesced into what became our moon. Enjoy the fantastic animation of that event at the top of this page before it disappears from the web.
We’re still just scraping the surface of our understanding of the universe. And yet, at the pointy end of human discovery, we’re seeing exponentially further and more clearly into the void beyond our pale blue dot. And just as we’re understanding more about the impacts that may have created life on this planet, we likewise have our eyes on those that might end it, or at least end our human epoch.
Specifically, we have something called Sentry, run by NASA’s Jet Propulsion Laboratory, which tracks near-Earth objects. Per its own description, “Sentry is a highly automated collision monitoring system that continually scans the most current asteroid catalog for possibilities of future impact with Earth over the next 100 years.” As the system picks up new asteroids in our neighborhood, it scans their size and probability of coming into contact with Earth. As it rules those possibilities out, they fall off the list.
Even if you’ve never looked at this site before, and have no idea what you’re looking for, one object stands out immediately from the rest. It’s the one with the “3” assigned to it on the Torino Scale, while all the others register a zero.
2024 YR4 is estimated to be 55 meters, or a shade over 180 feet, across. I first became aware of it last week, when Defector’s Barry Petchesky wrote about it, when it had just a 1.2 percent estimated chance of hitting Earth on its next pass.
For now, a 3 means the space rock in question “merits your attention.” As Petchescky notes, though, if the probability of an impact of a rock that size becomes a reality, the threat level rises to an 8. It is still very far away — 27 million miles, as of last week. It’s closer than that now, a fact I know, because I keep logging on to track its movements. By last Thursday, the impact probability had nearly doubled to 2.3 percent.
That this looming threat is inching closer in our telescopic mirrors as the underpinnings of liberal democracy start to creak is certainly a cosmic coincidence. Yet the looming specter of destruction — maybe somewhere far away; maybe somewhere that tangentially impacts you; maybe right on top of you — feels inescapable.
There’s something brain-breaking about holding humanity’s incredible ability to create and explore, to see and travel far beyond our own little space rock in the same thought as our sheer recklessness and myopic greed. Everything incredible we’ve ever achieved has come through massive, collective efforts that no one person could even begin to accomplish; nearly every wave of destruction that has set us back has flowed from the fragility and inadequacy of single individuals hellbent on shaping the world to their will.
A mid-sized asteroid strike is, if you’re looking for comps in human technological terms, on par with some of the weapons we’ve created in the last century. A 6.0 earthquake is equivalent to about a megaton of TNT. A 7.0 earthquake, like the one that derailed the 1989 Bay Bridge World Series, is equivalent to 32 megatons, and roughly as destructive as our largest thermonuclear weapon. 2024 YR4’s impact energy is estimated at 7.8 megatons.
This is not large enough to be an existential threat to humanity as a whole, but could be catastrophic on a local scale. Given my natural curiosity and disposition, it’s the kind of thing that would probably have captured my attention anyway. But it has stuck with me more rigidly, I believe, because the date of its potential impact is my 50th birthday.
The first thing I ever wanted to be was an astronaut. Playing on my bed at my grandparents’ house, where I lived for a year-and-a-half when I was three and four years old, I would dream of rocket ships and planets, and what might lie beyond. During the pandemic, when I was underemployed and trying to decide where my career would go next, I applied to every public affairs job NASA listed, always getting referred to the next step, but never getting an interview.
Last week, the agency spent most of Wednesday deleting DEI mentions from its website, instead of, you know, focusing on space.
As much as I absolutely do not want to hand it to “Don’t Look Up,” a deeply cynical, hopeless farce of our just-prior political moment, the thought that a government agency might not be truthful with us about an impending space rock hurtling inexorably toward us feels entirely in play at this point.
Beyond that, consider how much of our basic financial system and all we’ve taken for granted — things like our social security and the footing of our entire economy — have so quickly been shaken. It makes the very idea of thinking about the kinds of big, moonshot projects, of thinking in any clearheaded way about the future at all, feel almost impossible.
In sum, the events of the last two weeks have very much felt like the beginning of the end of the world we have known in our lifetimes. With no intervention, it feels like it will only keep slipping further away, into a less stable, less secure future for ourselves and whoever is unlucky enough to come next. Even if, somehow, the indiscriminate hammering inside the walls of our institutions stops immediately, there are enough fissures in what had already atrophied to make me doubt their ability to stay standing without some pretty fundamental reinforcements or renovations.
Probably — statistically, historically — everything will be OK, and the rock will miss us completely. Then again, that’s exactly the attitude that landed us here in the first place, logging on each day to see what’s hurtling our way.