KAHULUI, Hawaii — After years of study and failed proposals, NASA has decided to proceed with development of a space-based telescope to search for near-Earth asteroids.

Thomas Zurbuchen, NASA’s associate administrator for science, said Sept. 23 the agency will go forward with a mission called the Near-Earth Object (NEO) Surveillance Mission, a concept based on the NEOCam mission that was a finalist in the previous competition for Discovery-class planetary science missions.

A key difference for NEO Surveillance Mission, though, is that the mission will be “directed” by NASA, rather than competed through the Discovery or another program. The Jet Propulsion Laboratory will lead development of the mission under NASA’s planetary defense program.

Zurbuchen, speaking at a meeting of the agency’s Planetary Science Advisory Committee in Washington, said that the mission is more of an operational one, designed to meet a congressional goal of discovering at least 90 percent of the near-Earth asteroids at least 140 meters in diameter, rather than a science mission following the direction of decadal surveys.

“The only reason we want every 140-meter object is not because we need it to do all the science,” he said. “It’s because we want to understand whether one of them is on a collision course over time to Earth.”

Zurbuchen said that the new mission, strictly speaking, would not be a continuation of NEOCam. That mission, proposed in the previous Discovery competition, was one of the finalists, but not selected for flight in early 2017. NASA, though, did provide extended Phase A funding to support work on the infrared detectors the mission would use to search for asteroids.

“NEOCam was a [principal investigator]-class mission that was not selected, put into an extended Phase A, and then stopped,” he said. “The thing we invested time in is the instrument, that is going forward as part of a mission that has a lot of similarities to what NEOCam was conceived.”

The new mission, as described at the meeting, would fly a 50-centimeter telescope with a camera that operates in the infrared between 4 and 10 microns. The spacecraft would have a total mass of no more than 1,300 kilograms, allowing it to launch on a vehicle like an Atlas 5 or Falcon 9 to the Earth-sun L-1 Lagrange point. Once in space, Zurbuchen said the mission should reach the 90% congressional goal within 10 years, with an ticipated mission lifetime of 12 years.

The total cost of the NEO Surveillance Mission would be $500–600 million, with a launch no earlier than fiscal year 2025. The mission’s funding would come from the agency’s planetary defense program, currently funded at $150 million a year and finishing work on the Double Asteroid Redirection Test (DART) mission for launch in 2021.

That approach appears to be along the lines of what many in the planetary defense community were looking for. In recent months, they had argued for using the planetary defense budget to support a series of missions, including a NEOCam-like observatory and others to study specific near Earth objects.

The decision to proceed with the new mission raised questions at the meeting about what would happen to the team that worked on NEOCam, including principal investigator (PI) Amy Mainzer, who recently moved from JPL to the University of Arizona. “I expect the former PI of NEOCam to have a really crucial role,” Zurbuchen said, but added he didn’t plan to prescribe a decision on that role.

“We’re working it out,” Mainzer, in attendance at the meeting, said.

The core NEOCam science team will also likely be involved in the new mission, said Lindley Johnson, head of NASA’s Planetary Defense Coordination Office. However, he said there may be calls for additional participating scientists for the mission.