NASA is finally getting serious about a major threat to life on Earth.
Administrators announced on Monday that the agency is planning to launch a space telescope to watch for hazardous asteroids as part of its planetary defense strategy.
The telescope will use infrared radiation to detect the heat of rocks hurtling through space. For now, NASA administrators are calling it the Near-Earth Object Surveillance Mission (NEOSM).
"This is a great step forward for thinking about human destiny, because the dinosaurs certainly did not have an asteroid survey program to protect themselves," Richard Binzel, an asteroid researcher and professor of planetary sciences at MIT, told Business Insider. "Having knowledge of what's out there is something that the planetary science community has been advocating for for nearly 30 years. So this is a breakthrough decades in the making."
NASA's new mission is expected to cost between $500 million and $600 million. It could launch as early as 2025, though that's not an official timeline.
"We're finally in a position where we can say we're ready to move forward," Lori Glaze, director of the agency's Planetary Science Division, said in a NASA committee meeting. "It's a really big deal that we're at this point."
'Planet defense is something that we have to deal with'
Any space rock with an orbit that takes it within 125 million miles (200 million kilometers) of the sun is considered an NEO (near-Earth object). So far, humanity has located about 15,500 such objects.
The goal in monitoring NEOs is to avoid a surprise like the dinosaurs got 65 million years ago, when a 6-mile-wide asteroid crashed into Earth's surface. The impact caused a mile-high tsunami, sparked wildfires, and released billions of tons of sulfur into the atmosphere, blotting out the sun for years. That was the end of the age of big lizards.
But so far, scientists have missed plenty of large, dangerous objects that approached Earth. In 2013, a meteor measuring 20 meters (about 65 feet) in diameter and traveling at 40,000 mph entered the atmosphere and exploded over Chelyabinsk in central Russia. The blast sent out a shock wave that broke windows and damaged buildings across the region, injuring more than 1,400 people.
According to NASA modeling, an event like the Chelyabinsk meteor occurs about every 60 years. That same day, another, larger asteroid came within 17,000 miles of Earth.
"Space reminds us from time to time that, yes, on a historic timescale, a geologic timescale for sure, planet defense is something that we have to deal with," Thomas Zurbuchen, an associate administrator at NASA, said in the committee meeting.
Space sent us another such reminder in July, when a 427-foot-wide, "city-killer" asteroid flew within 45,000 miles of Earth.
NASA had almost no warning about that rock because right now, the only way scientists can track an NEO is by pointing a telescope in the right place at the right time. Telescopes detect the sunlight that asteroids reflect, but the smaller the asteroid, the fainter the reflection; plus, some asteroids just aren't very reflective.
"Luck is not a plan, and up to now we've been relying on luck," Binzel said.
NASA hopes to address that problem with the NEOSM telescope. The agency hasn't released design plans or an official timeline for the project yet, but said it will make use of previous plans for a similar mission, called NEOCam, which never got fully funded. The NEOCam telescope would have orbited Earth and scanned the sky for NEOs larger than 140 meters (460 feet) — large enough to cause regional damage if the object crashed into Earth.
Similarly, the plan for the new asteroid-hunting telescope calls for heat-sensing infrared sensors capable of detecting even dark asteroids, which are the most difficult to find. (Since space rocks get warmed by the sun, they emit infrared light, even when they're too dark for ground-based telescopes to see.) The infrared sensors will also allow the telescope to measure the shape, size, composition, and orbit of incoming objects.
NASA's 8-year-old Wide-field Infrared Survey Explorer (WISE) telescope has used a similar infrared-monitoring approach to find at least 230 NEOs.
However, WISE is less powerful than NEOCam would have been, has a smaller field of view, and relies on an older camera that requires cryogenic cooling. Plus, WISE wasn't designed solely to hunt asteroids. Its primary mission, which it completed in 2011, was to image the entire sky twice, rendering remote galaxies, stars, and asteroids in detail.
'A huge step forward'
In 2005, Congress directed NASA to track down 90% of near-Earth asteroids with a width of 140 meters or more by 2020. As of December, however, telescopes on Earth and in space had found less than one-third of these NEOs.
The proposal for NEOCam was put forward in 2006, then again in 2010. NASA selected the 2010 proposal for technology development, but chose to fund other projects for launch when it came time to pick new missions in 2017.
"There's just been this impasse between NASA and the Congress over how to do it and how to pay for it, and what happened today was a huge step forward," Binzel said.
He added that the new telescope "sounds like NEOCam in every way except name."
But there's one key difference: The new telescope will employ a new team of scientists.
"It's nice to have it move forward, but when you start changing the team up, then that creates additional risk," Mark Sykes, director of the Planetary Science Institute and a scientist on the NEOCam team, told Business Insider. "It just increases the probability of not the best decisions being made. That could impact how well a mission operates and what we get out of it."
Zurbuchen said the project will still involve the NEOCam team, though. And ultimately, the decision is a step toward getting an asteroid-hunting telescope into orbit.
"This is the first time NASA has ever voiced a commitment to flying a space-based asteroid survey," Binzel said. "They've always said 'we'll study it, we'll study it,' and now they say 'we are going to do it.'"
Dave Mosher contributed reporting to this story.