These are the asteroids that scare scientists. Are we prepared for them?Global cooperation is, unsurprisingly for a threat that comes from the stars, essential.
https://www.washingtonpost.com/opinions/interactive/2024/asteroids-nasa-strike-extinction-preparation/?itid=hp_opinions_p002_f001The asteroid that wiped out the dinosaurs some 66 million years ago was a once-in-a-250,000-century event; Earth is nowhere near due for another. In fact, smaller space rocks — not species-killers, but still big enough to cause catastrophe — are the ones that really worry experts. The planet should ensure it’s ready for them. Thankfully, humans have more tools than the dinosaurs did to face the threat.
Naturally, the bigger an asteroid is, the more damage it does. But there are many more small asteroids than large ones, and that means these hit the Earth (or come close to it) more frequently. Because they’re smaller, they are, of course, more difficult to detect.
So-called dinosaur-killers are multiple miles in diameter: Imagine a slightly rounder version of Mount Everest hurtling toward us through space. Scientists say they already know the location of 95 percent of asteroids large enough to cause a potential global catastrophe (admittedly, this leaves an unsettling question: What about the other 5 percent?), rendering them less worrisome than their size might suggest. The smallest of small asteroids are similarly not a concern; about the size of a car, they tend to burn up in the atmosphere without having the chance to wreak any havoc.
That leaves the Goldilocks asteroids — those that are just right, or just wrong. They’re small enough to escape earthly notice, and large enough to do real damage. These are the rocks that scare the scientists who study them. Some are about 150 meters in diameter. They arrive every 20,000 years or so and could cause mass casualties across a state or small country. Others measure around 50 meters, and they arrive approximately every 1,000 years. That might seem like a long time, but not when they could devastate a major metropolitan area.
How it looks in real life
Photos of the recently discovered 500-foot-wide asteroid 2024 MK, which came within about 184,000 miles (295,000 kilometers) of Earth — closer than the distance between the Earth and the moon.
The good news is that researchers don’t know of any asteroid on course to collide with Earth within the next 100 years that has the capacity to cause serious damage. The bad news: It doesn’t mean that none exist. Right now, astronomers think they’ve found somewhere around 40 percent of those country-smashing asteroids and just more then 10 percent of the city-destroyers. We’ve already gotten a hint of what could happen if one gets through without warning: Remember the meteor — about 20 meters wide — that obliterated about 50 acres’ worth of window glass in the Russian city of Chelyabinsk in 2013? The shock wave also leveled a forest. About 1,500 people were injured.
Kelly E. Fast, NASA’s acting planetary defense officer — it’s nice to know there is such an official — says that the “greatest gift we can give our planet is the luxury of time.” Step 1 to achieving that is pretty obvious: Find the asteroids. Encouragingly, scientists are already on the hunt, with NASA and partners around the world scanning the sky every night with telescopes down here on the ground. The problem is, these telescopes have their limits.
Asteroid Apophis
will fly 20,000 miles
from the Earth in 2029
This one will come close, but it's harmless
This is a visualization of Apophis, an asteroid about 1,100 feet wide (340 meters) expected to fly 20,000 miles from Earth on April, 2029. Some satellites orbit this region, but scientists expect Apophis to pass by harmlessly.
Asteroids don’t glow like stars do, so infrared technology operating not thousands of miles from space but right smack in the middle of it is the ideal way to spot them. NASA recently confirmed it would launch the space-based Near-Earth Object Surveyor telescope toward the end of the decade. The agency believes this tool will help detect more than 90 percent of the most potentially devastating asteroids within the following 10 years.
Just spotting an asteroid on a trajectory to blow a hole in the planet isn’t especially useful if humankind can’t do anything about it, however. NASA’s Double Asteroid Redirection Test (DART) mission two years ago successfully slammed a spacecraft about the size of a golf cart into an asteroid about the size of the Great Pyramid of Giza. By doing so, the agency altered the asteroid’s orbit. This was merely proof of concept; the asteroid in question never endangered Earth. Now, though, experts know that humans can employ the same concept for asteroids that actually pose a threat.
Next comes ensuring that governments employ it effectively. The European Space Agency is launching a mission later this year to revisit the asteroid, so that it can measure exactly what effect DART had. How much of a shove is necessary to move an asteroid just enough to avoid a collision course with Earth? And how does that calculation relate to the asteroid’s particular properties — its mass, its elasticity and more? (Not all rocks, it turns out, are actually rock-hard.) Then, when an asteroid is identified, NASA or a global partner would ideally conduct a flyby to collect the data necessary to determine whether a response is necessary and, if so, what kind. That way, when scientists see an asteroid coming, they know what to do.
There are a few ways to alter the trajectory of an asteroid, of which the method used in DART — known as kinetic impact — is only one. Scientists have also contemplated nudging asteroids more gently, such as by positioning a spacecraft nearby and letting its gravitational pull (what former NASA planetary defense officer Lindley Johnson has called “nature’s tug rope”) slowly change the asteroid’s path. More tantalizing for science-fiction fans, a spacecraft could shoot ion beams at the asteroid — sending a high-velocity beam of plasma into the object at precisely the right angle, for precisely the right duration.
These methods work best when there’s ample time to act before an asteroid’s predicted strike. If there is less time, the only recourse might be the nuclear option. This is only slightly less dramatic than it sounds: An atomic device could be detonated not on top of an asteroid but next to it instead.
Oh, and one more quick note. Earth needs to be ready for the asteroids it doesn’t manage to move — or decides aren’t worth moving. NASA and the Federal Emergency Managament Agency recently released the results of an exercise they conducted involving a hypothetical never-before-detected asteroid that looked likely to hit the planet in 14 or so years. Participants included representatives from across U.S. government agencies, as well as international partners. That’s a good start: Every country, including this one, needs to know who’s responsible for what when it comes to diverting asteroids, as well as containing the damage if diversion fails. There’s a lot to cover, from public communications to possible evacuations and beyond.
Global cooperation is, unsurprisingly for a threat that comes from the stars, essential. The U.N.-facilitated International Asteroid Warning Network already connects observers across the world. If the threats meet certain criteria, the Space Mission Planning Advisory Group, also a U.N. body, kicks into gear, bringing together leaders of space agencies from NASA to the European Space Agency, as well as Russia’s Roscosmos and the China National Space Administration to prepare options for reconnaissance and deflection. Some ground rules today could stave off tension tomorrow. Changing an asteroid’s trajectory takes time, and as its path shifts so does its “risk corridor” — basically, where it has the highest chance of striking. Imagine the drama should ultimately sparing Beijing mean temporarily endangering Tokyo.
Mr. Johnson of NASA has pointed out that a large asteroid hitting the planet might well be the only natural disaster, amid tsunamis and earthquakes and sun storms and beyond, that humanity has the technology to predict so far in advance that we can actually prevent it. It would be foolish not to try.
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