NASA’s new Nancy Grace Roman Space Telescope could unveil clues to the mysterious dark energy that accelerates the expansion of the universe, and discover more than 100,000 planets outside of our solar system.
The key component that makes that possible — the mirror that bounces light from the cosmos to the camera and other instruments — comes from a canceled spy satellite.
A decade and a half ago, prospects for a proposed mission that astrophysicists hoped would shed light on dark energy appeared to be dimming.
The Wide-Field Infrared Survey Telescope, or WFIRST, was to be NASA’s next big astronomy mission, costing more than a billion dollars to build. Its observations at infrared wavelengths would help astrophysicists precisely calculate the rate of the universe’s expansion over billions of years.
But many astronomers, especially those studying planets outside the solar system, merely yawned, because the proposed telescope’s five-foot-wide mirror would be too small to be of much use to them.
“It was very hard to get much enthusiasm,” said Alan Dressler, who had led a committee that declared WFIRST the top priority for a large space-based mission in 2010.
Then, the National Reconnaissance Office showed up bearing the gift of larger mirrors, already built but unused.
For telescopes, both those pointing down at Earth and those gazing outward into the cosmos, curved mirrors act as telephoto lenses, and bigger mirrors collect more light. For a spy agency, this helps reveal smaller details on the ground. For astronomers, bigger mirrors mean they can see dimmer celestial objects, farther away.
The secretive agency had a couple of mirrors, presumably intended for next-generation spy satellites, that it no longer needed.
In January 2011, a NASA official, Michael Moore, received the phone call offering the mirrors, which are nearly eight feet wide and as expansive as the one used in the Hubble Space Telescope.
A year later, the space agency accepted the offering. The mirrors opened the door to more ambitious science goals for WFIRST, which was later renamed to honor Dr. Roman, the first chief of astronomy at NASA, who died in 2018.
The telescope is scheduled to launch on Sunday.
Mr. Moore was circumspect about revealing any details, but said he had learned several years earlier of the mirrors sitting in storage, unused. “I’m not really at liberty to say who I spoke to at the time,” he said.
He had asked the people working on the classified project if they might be willing to give the mirrors to another agency, like NASA. The answer then was no, and he heard nothing more until the phone call.
“I think they just finally got around to figuring out what they wanted to do, and I was the first name that they remembered,” Mr. Moore said.
When the donation was announced in June 2012, an N.R.O. spokeswoman said the hardware was built in the late 1990s and early 2000s. That fits the timeline of the spy agency’s Future Imagery Architecture program, which was aiming to build advanced telescopes looking down at Earth to reveal to intelligence agencies what their adversaries were doing. The program was canceled in 2005.
John Grunsfeld, a former NASA astronaut, was deputy director of the Space Telescope Science Institute in Baltimore when the initial WFIRST design was unveiled in 2010, and he was among those who were disappointed.
“We were sort of depressed that that’s the best that the astronomy community can come up with,” Dr. Grunsfeld said.
When he became the head of NASA’s science directorate in January 2012, he found out he could make WFIRST better.
“To me, it was super obvious from the start,” Dr. Grunsfeld said, that one of the two N.R.O. mirrors would be repurposed for the dark-energy telescope.
The larger mirror would collect 2.5 times as much light, increasing the scientific payoffs for WFIRST.
Dr. Grunsfeld also wanted to add a coronagraph, a disk that blocks out the light so that planets around a star can be seen.
That would make WFIRST more appealing to the planet-finding astronomers, and provide a technological proof of concept.
After consulting with NASA experts, Dr. Grunfeld turned to Matt Mountain, the director of the Space Telescope Science Institute, to put together a small group of scientists and engineers to get an independent opinion on the possibility of building a camera and coronagraph around the existing telescope — still a secret outside of the government — at a reasonable cost.
“That was the challenge he set us,” Dr. Mountain said.
Within weeks, a sprint for a study like this, the answer came back: yes.
The tentative plan was revealed publicly soon after that.
The next hurdle: There was no money in NASA’s budget to start work.
Dr. Grunsfeld made the case to the Office of Management and Budget that recycling the N.R.O. mirror in a NASA telescope was a prudent use of taxpayer dollars that had already been spent, and the increased capabilities would ensure American leadership in the field.
“O.M.B. looked at that in some detail and said that sounds like a good idea,” Dr. Grunsfeld said.
Even though the Obama administration proposed deep cuts to NASA’s astrophysics program, there was enough money to get the telescope started.
During President Trump’s first term, his administration repeatedly sought to cancel the telescope. Each time, Congress, with both Republican and Democratic support, provided the financing to keep it on schedule.
The fate of the second mirror is unclear. During a news conference last month, Shawn Domagal-Goldman, the astrophysics division director at NASA, said, “There’s no current plans that NASA has, that I’m aware of.”
But Dr. Grunsfeld said that NASA had been asked to return it, and has not had possession of the second mirror for quite a while.
In a statement, the National Reconnaissance Office acknowledged its role in providing a key component for the Roman telescope, but offered few additional details.
“This act of interagency collaboration represents our commitment to the responsible stewardship of national assets,” the statement said. “By identifying advanced hardware no longer required for the N.R.O.’s mission, we were able to partner with NASA to help meet their highest-priority science objectives.”
Soon astrophysicists might finally get the data they have waited decades for, which could explain why the expansion of the universe is accelerating.
“Our current model of the universe is broken,” Dr. Mountain said. “So it would be good to understand what’s going on.”
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