Fifteen years later, a report from the National Academies of Sciences revealed that NASA was nowhere near that goal and could not possibly reach it with current telescopes.
After that – and the kick in the pants of 2019 OK – NASA has now allocated $600 million to build a space telescope specifically designed to image many of the missing asteroids.
This mission, called NEO Surveyor, is scheduled to launch in 2026. Until then, there are still a few ways an asteroid could sneak up on us.
Some asteroids come in from the direction of the sun, and “telescopes work at night,” says Brown. That’s part of how 2019 OK slipped through NASA’s net. The Chelyabinsk Meteor, a 20-meter-tall rock that exploded over Russia in 2019 with the force of about 500 kilotons of TNT, performed the same trick.
Alternatively, an asteroid could have a very elliptical orbit that would place it far from Earth so we wouldn’t see it until it was too late, Brown says. “There will always be a small chance.”
But astronomers have more and more tools to spot asteroids. Space-based telescopes can detect them in visible or infrared light, as can visible-light telescopes on Earth.
And scientists have gotten very good at using large dishes like the ones at the Canberra Deep Space Communication Complex to hit asteroids with radio waves; other dishes can then pick up the radio reflections and determine the shape and trajectory of the rock.
“Until recently, most surgeries were performed in the United States. But four or five years ago we developed a lot of these techniques here in Australia – and we are now among the best in the world when it comes to planetary defense,” says Guifre Molera Calves, who works on planetary defense observations at the University of Tasmania .
This morning’s DART collision will give us even more useful data. We should soon know how far he managed to move the asteroid out of orbit. If it’s a lot, it gives us confidence that we can successfully push asteroids away if they’re fairly close to Earth. If DART has barely moved it, we know we have to intercept much more distant rocks, says Dr. Brad Tucker, astronomer at the Australian National University. This data can then inform our asteroid surveys.
Billionaires and Bulldust
SpaceX billionaire Elon Musk has long warned of the civilizational risk posed by killer asteroids. That’s one of the reasons he thinks we should colonize Mars.
However, what has surprised me today when I speak to scientists tasked with discovering these killer asteroids is… they’re generally a lot less concerned than Musk.
Brad Tucker: “We don’t have to worry about that unnecessarily – not as much as one would think.”
Michael Brown: “In the short term, planetary defense is much cheaper and more feasible with existing technology than setting up a plan B on Mars.”
Professor Phil BlandFounder of the Desert Fireball Network for tracking meteorites: “We know that we are very unlikely to be hit by anything that will cause major damage in the next century.”
Scientists studying a risk are usually most concerned about that risk, so this level of optimism is interesting. Where does it come from?
Bland says that since the mid-1990s we’ve gotten very good at tracking the largest objects — those more than a kilometer wide. “And we can be pretty sure that nothing big is breathing down our necks.”
But over a long enough period of time, isn’t it inevitable that a killer asteroid will hit Earth? “Statistically yes — if your stats are flawed,” says Tucker. “But when your time frames are thousands to tens of thousands of years, it’s not quite the same argument.”
When such an object crosses our path, we have a long notice – on the order of decades. That should (surely?) be long enough for us to pull ourselves together.
For example, compare the risk of an asteroid to the risk of a pandemic. Before the mid-1990s, we didn’t know how much of an asteroid impact risk we were, and we didn’t have tools to deal with it. Now we do. Yet we still lack the tools to know where the next pandemic is coming from – or to stop it if it does.
Our ability to detect and deflect asteroids is a true triumph of science, says Bland. “Now we’re actually in a much better place to deal with them.”
did you like this article? The Examine newsletter explains and analyzes science with a rigorous focus on evidence. Sign up to receive it every week.
https://www.smh.com.au/national/is-earth-ready-for-a-killer-asteroid-20220927-p5blal.html?ref=rss&utm_medium=rss&utm_source=rss_national Can NASA detect an asteroid before it hits Earth?