But efforts to launch such an asteroid observatory have failed to advance for years.
Now, NASA's NEO Surveyor mission may finally move forward if it passes a key review in the coming weeks.
An asteroid big enough to wipe out a city could be careening towards Earth right now, and it's very possible nobody would notice until too late.
As far as we know, that isn't happening - the odds of a large space rock striking the planet are low. Still, researchers agree that it will occur eventually, which is why experts from around the world practiced for this possibility last month.
The results were unencouraging. At the Planetary Defense Conference, a group of 200 participants from about two dozen countries worked through a hypothetical scenario in which an asteroid was set to crash into Earth in six months. They determined that no existing technologies could stop the space rock, since the time frame was too short to launch a mission that could destroy or deflect an asteroid.
To successfully protect the planet from such a threat, experts estimate, they'd need five to 10 years' warning.
"What you want to do is find them early, find them as early as possible - as in years, or even decades, before they pose a threat," Paul Chodas, the manager of NASA's Center for Near-Earth Object Studies, told Insider. "The dinosaurs didn't have a space program, and look what happened to them. We have a space program. And given enough time, we can do something about this threat. It's one of the few natural threats we actually have the technology to basically mitigate."
NASA intends to catalogue nearby asteroids over time and chart their paths through the solar system, so that someday - if necessary - humanity could have a shot at destroying or deflecting any space rocks headed for Earth. But to do that, the agency needs a space telescope that doesn't exist yet. Called the NEO Surveyor Mission (NEO stands for near-Earth object), it's scheduled to launch into Earth's orbit in 2026.
At least, that's the tentative timeline. For years, work on this kind of infrared telescope has been caught in "NASA mission limbo hell," according to MIT astronomer Richard Binzel. No proposal has progressed beyond early development, so engineers and scientists haven't started building any such telescope for flight yet, much less preparing for launch.
"Every day we wait is one day less that we have the information we need to make a response," Binzel, who studies potentially hazardous asteroids, told Insider. "What that means is, for now, we are relying on luck to keep us safe from major asteroid impacts. But luck is not a plan."
However, NASA conducted a critical review of the NEO Surveyor last month, which should determine whether the mission will finally get funding to move forward. Amy Mainzer, who leads the project, told Insider it "seemed to go well," but NASA has not announced its decision yet.
NASA needs to find any asteroids big enough to crush a city
In August, an asteroid the size of a car passed closer to Earth than any known space rock had ever come without crashing. It missed our planet by about 1,830 miles.
Astronomers didn't know the space rock existed until about six hours after it whizzed by.
Because of its small size, that asteroid probably wouldn't have posed any danger had it struck - it would have burnt up in the atmosphere. But its surprise visit highlighted a major blind spot: Nobody saw it coming because it was approaching from the direction of the sun. Telescopes on the ground can only observe the sky at night, which means they miss almost everything that flies at us from the sun.
By scouting from a position in space, the NEO Surveyor would be able to look towards the sun. And since it would use infrared light, it could also spot asteroids that are too dark for Earth-based telescopes.
But the mission is no guarantee. Plans for this kind of a space telescope have been in the works since 2005, when Congress mandated that NASA find and track 90% of all near-Earth objects 140 meters (460 feet) or larger in size. That's big enough to obliterate a city like New York.
The initial deadline was 2020. According to Chodas, NASA has only spotted about 40% of those objects so far.
'Stuck in the same place we have been for at least 5 years'
NASA turned down a similar asteroid-tracking space telescope mission - called NEOCam - three times.
Mainzer first submitted the idea in 2006, but NASA declined to take it on as an official mission. The agency passed again when she submitted another proposal in 2010. NASA did, however, allot some funding to develop technology for the telescope's electronic detectors.
Then came a reminder from space. In 2013, a house-sized asteroid screamed into the skies above Chelyabinsk, Russia and exploded. The blast sent out a shock wave that broke windows, damaged buildings, and injured more than 1,400 people. No one on Earth saw it coming. That same day, a larger asteroid came within 17,000 miles of the planet.
Jim Bridenstine, who served as the Trump administration's NASA Administrator, said in 2019 that the agency's modeling suggests an event like the Chelyabinsk meteor occurs about every 60 years.
Mainzer proposed the NEOCam mission once more in 2015, to little avail, though NASA did grant the telescope an extra year of funding for further development. NEOCam never became an official NASA mission.
Then, several years later, another near miss: A 427-foot-wide, "city-killer" space rock flew within 45,000 miles of Earth in 2019. NASA had almost no warning about it.
Two months later, the agency announced that it was officially taking on a new mission called NEO Surveyor - which sounded a lot like NEOCam, just with a different name and some different team members.
"While NEO Surveyor is based on the previous NEOCam concept, it is more closely focused on planetary defense requirements," a NASA spokesperson told Insider in a statement.
Binzel called the decision "a huge step forward," though it has yet to move past early development. NEO Surveyor is still in what NASA calls "Phase A" - a stage focusing on design and technology development.
The team has been designing infrared camera chips and planning how to load the telescope onto a rocket, according to Mainzer.
"We really just tried to focus on the technical work and making sure that we can do the best job that we can, so that when we do get into Phase B, we can hit the ground running," she said.
Binzel said a lot of the holdup has to do with NASA's budget.
"The sticking point is in Congressional appropriations," he said. "NASA has repeatedly and publicly said 'we're ready to do this.' But it never gets appropriated in the budget."
To move NEO Surveyor forward, Binzel added, NASA's planetary-defense program would need about $225 million per year. Last year it got $150 million.
"My sense is that asteroid impacts are so unlikely in a two-year Congressional term, they don't get much focus," he said.
NASA is deciding whether to move NEO Surveyor forward
If NASA decides that the NEO Surveyor Mission is ready for Phase B, the team could then start building prototypes and developing hardware and software.
"The NEO Surveyor project will be notified of the outcome in the coming weeks," the NASA spokesperson said.
NASA's budget request for 2022 allots $197 million for planetary defense, including $143 million for NEO Surveyor, but Congress must still approve it. That would be a significant increase in funding from the $28 million the mission received in 2021. NASA Associate Administrator Thomas Zurbuchen estimated in 2019 that developing the telescope could cost about $500 to $600 million in total.
"The budget for planetary defense is able to move NEO Surveyor through Phase B," NASA said.
Mainzer said that if the project does move ahead to the next phase, the team would be on track for a 2026 launch. Otherwise, the mission could be delayed further. NEO Surveyor was originally set to launch in 2025, but that's already been bumped back.
"I think this mission is the right thing to do," Mainzer said. "This is not a problem that people should stay awake worrying about at night, but it's something we'd like to cross off our list."
Aylin Woodward contributed reporting.
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