Asteroid moon Dimorphos as seen by NASA’s DART spacecraft 11 seconds before the impact that shifted its path through space, in the first asteroid deflection test.
Johns Hopkins University/NASA Applied Physics Laboratory
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Johns Hopkins University/NASA Applied Physics Laboratory
Imagine if scientists discovered a giant asteroid with a 72% chance of hitting Earth in about 14 years—a space rock so big it could not only destroy a city, but devastate an entire region.
That’s the hypothetical scenario recently discussed by asteroid experts, NASA officials, federal emergency management officials and their international partners as part of a tabletop simulation designed to improve Earth’s ability to respond to future asteroid threats, according to a just-released report. space agency.
“Right now, we don’t know of any significant-sized asteroids that will hit Earth in the next hundred years,” says Terik Daly, chief of the planetary defense section at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
“But we also know,” says Daly, “that we don’t know where most of the asteroids are that are large enough to cause regional devastation.”
NASA experts and Federal Emergency Management officials dealing with a hypothetical incoming asteroid threat in April 2024.
Ed Whitman/NASA/Johns Hopkins University Applied Physics Laboratory
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Ed Whitman/NASA/Johns Hopkins University Applied Physics Laboratory
Astronomers estimate there are about 25,000 of these “near-Earth objects” that are 140 meters or larger in diameter, but only about 43% have been found so far, according to materials prepared for a tabletop exercise held in Laurel in April. , Md.
The event was just the latest in a series of exercises planetary defense experts hold every few years to practice how to handle reports of a potentially planet-threatening asteroid — and the first since NASA’s DART mission, which showed that a spacecraft to an asteroid could alter its path through space.
This time, just after the discovery of the fictitious asteroid, scientists estimated its size at 60 to almost 800 meters in diameter.
Even an asteroid at the smaller end of that range could have a big impact depending on where it hits Earth, says Lindley Johnson, NASA’s planetary defense officer emeritus.
While “a 60-meter asteroid hitting the middle of the ocean somewhere” wouldn’t be a real problem, he says the same asteroid hitting land near a metropolitan area would be a “serious situation.”
Because telescopes would see such an asteroid as just a point of light in space, Daly says, “we’re going to have very large uncertainties in the properties of the asteroid, and that leads to very large uncertainties about what the consequences would be if it were to impact the earth and also large uncertainties about what it would take to bring that asteroid down to earth.”
What’s more, this particular scenario alarmingly stipulated that scientists wouldn’t be able to learn more about the threat for more than six months, when telescopes could again spot the asteroid and make further assessments of its trajectory.
Participants in the exercise discussed three options: simply wait and do nothing until the next telescope observation; the launch of a US-led space mission for a spacecraft to fly by an asteroid to gather more information; or creating an effort to build a more expensive spacecraft capable of spending time around an asteroid and possibly altering its path through space.
Unlike previous asteroid threat simulations, this one did not come to a dramatic end. “We were actually stuck in one point in time for the duration of the exercise. We weren’t moving forward quickly,” says Daly.
As a result, participants had ample time to discuss how to communicate uncertainties and the urgent need for action. They also discussed how funding and other practical considerations might play a role in decision-making processes in federal agencies and Congress.
Daly says that in previous discussions, tech experts tended to assume that access to funding would not be an issue in such an unprecedented situation, but “the reality is that cost was an issue and a factor.”
NASA’s report on the exercise notes that “many stakeholders expressed that they would like as much information about the asteroid as soon as possible, but expressed skepticism that funding would be available to obtain such information without definitive knowledge of the risk.”
While representatives of space institutions clearly preferred swift action, “what would political leaders actually do?” Daly says. “That was really an open question that persisted throughout.
Preparing some kind of spacecraft, finding the right launch window for it, and having it travel through space to an asteroid “takes ten years pretty quickly,” Johnson says. “So that’s definitely a problem when we look at it from a technology perspective.”
But something like 14 years in advance will seem like a lot of time to emergency managers and disaster responders, says Leviticus “LA” Lewis, a Federal Emergency Management Agency employee assigned to work with NASA.
Lewis notes that emergency managers would have to think about allocating resources to this seemingly distant threat while responding to more immediate dangers like tornadoes and hurricanes. “It’s going to be a special challenge,” he says.
Meanwhile, NASA is on track to launch a new asteroid-hunting telescope in the fall of 2027, Johnson says.
“We need to find out what’s out there, determine their orbits, and then determine whether they pose a risk of impacting Earth over time,” he says.