NASA to build telescope for detecting asteroids that threaten Earth

NASA is moving forward with plans to launch an infrared telescope that could detect asteroids on a collision course with Earth. Its launch could come by the middle of the next decade, Thomas Zurbuchen, NASA’s associate administrator for science in Washington, D.C., said today at a meeting of an agency advisory panel.

The Near-Earth Object Surveillance Mission, which will cost $500 million to $600 million, grows out of long-gestating plans for the Near-Earth Object Camera (NEOCam), first proposed by NASA’s Jet Propulsion Lab (JPL) in Pasadena, California, nearly 15 years ago. Such a scope is essential for meeting a congressional requirement that NASA detect 90% of all potentially hazardous asteroids and comets of at least 140 meters in diameter by the end of 2020. The telescope will likely end up with a different name, but the mission is the same, says Mark Sykes, CEO of the Planetary Science Institute in Tucson, Arizona, and a member of NEOCam’s science team. “There is no independent or new spacecraft or operational design here. This mission is NEOCam.”

Although NASA will not meet Congress’s deadline—which wasn’t attached to any funding—a combination of an infrared telescope and the Large Synoptic Survey Telescope, a ground-based facility being built in Chile, will eventually make it a reality, the National Academies of of Sciences, Engineering, and Medicine in Washington, D.C., said this summer in a report. A telescope operating in the infrared spectrum is essential, researchers say, as the past decade has shown that dark asteroids, which are nearly invisible in visible light but stand out in infrared, are more abundant than once thought. “There are a lot of really dark asteroids out there,” says Jay Melosh, a planetary scientist at Purdue University in West Lafayette, Indiana, and an author of the report. “That pushes the need for the infrared system.”

Building the infrared telescope, however, could require an increase in NASA’s $150 million annual budget for planetary defense. Most of that money now goes to the Double Asteroid Redirection Test (DART) mission being built by Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland. Set for launch in 2021, DART seeks to test whether it’s possible to deflect the path of an asteroid. It’s unclear whether congressional appropriators will follow NASA’s lead and also fund the new infrared telescope.

The mission also marks perhaps the first time that NASA has taken a mission proposal developed by an outside group for one its competitive science programs and proposed running it internally, Sykes says. The move could recast the role of Amy Mainzer, an astronomer at the University of Arizona in Tucson who has led NEOCam since it was first proposed, and her science team. Mainzer, who recently moved from JPL to the university’s Lunar and Planetary Laboratory, would have served as the mission’s principal investigator.

“I’m hearing [today’s news] at the same time as everyone else,” says Mainzer, who serves on NASA’s Planetary Science Advisory Committee, which is meeting today in Washington, D.C. “It sounds like NASA is interested in pursuing this, which I think is great. … It’s a problem worth solving.” The role that she and her university will play is not yet worked out, however.

Over the past 15 years, with NASA support, Mainzer’s team has refined the electronics and sensors that will power the telescope. Unlike a predecessor infrared telescope, the Wide-field Infrared Survey Explorer (WISE), NEOCam sensors will be able to operate without active refrigeration when parked at L1, a stable vantage point balanced between the gravity of Earth and the sun. Engineers, meanwhile, have dramatically lowered the “dark currents” of its detectors, spurious noise that occurs when the detectors are operated even in pitch black conditions.

Not everyone has been a fan of NEOCam’s plans. Nathan Myhrvold, a billionaire technologist and former Microsoft chief technology officer in Bellevue, Washington, has faulted the statistics used by Mainzer and others to generate asteroid diameters from observations of the WISE instrument, among other issues. The congressional mandate, passed in 2005, that NEOCam was designed to solve also seems increasingly irrelevant. One change is that researchers now think asteroids smaller than 140 meters in diameter also pose potentially serious threats to Earth, in part because they could generate damaging tsunamis. “The goal as defined [by Congress] does not represent any sort of a threshold that amounts to success if you achieve it versus failure if you don’t,” says Alan Harris, a planetary scientist at MoreData in La Canada, California. “It’s just a random benchmark on the field of play.”

The decision by NASA to pursue the telescope comes after an embarrassing episode this summer, reported earlier this month by BuzzFeed. The agency and ground-based telescopes failed to identify, until the last minute, a slow-moving, football field–size asteroid, named 2019 OK, that passed just 65,000 kilometers from Earth. It’s unclear whether NEOCam would have detected that asteroid, though it is expected to study asteroids under the 140-meter threshold, as well.

It is a good move by NASA to move the telescope out of its science funding portfolio, Harris adds. Planetary scientists have doubted NEOCam would yield important new research, a suspicion that likely derailed it in past competitions. That doesn’t make getting this data less worthwhile for society, however, Melosh says. “It’s something that we really need to do,” he says. “It may not be absolutely the best science, but there’s more to life than scientific knowledge.”

This is a developing story.