NASA has a mission for grounded spy telescopes
BY STEPHEN CLARK
Posted: June 4, 2012
A National Reconnaissance Office telescope built in secret to collect intelligence for the U.S. government could be the linchpin in NASA's quest to build a satellite to detect extrasolar planets and study the nature of dark energy, the mysterious force driving the expansion of the universe.
"When I first heard about this, my jaw dropped," said David Spergel, a researcher at Princeton University and co-chair of the National Research Council's Committee on Astronomy and Astrophysics.
Spergel and other scientists helped NASA verify the suitability of the spy telescopes, which were designed to look down on Earth, for the very different mission of peering into the cosmos.
NASA took ownership of two optical telescopes in August 2011, but the space agency did not reveal the transfer until Monday, when officials briefed the astrophysics science community and stories appeared in the New York Times and the Washington Post.
The National Reconnaissance Office, which owns and operates the U.S. government fleet of surveillance satellites, declassified the telescopes. The hardware may have been intended for use on high-resolution optical spy platforms, which collect digital imagery for intelligence analysts.
NASA officials would not disclose which programs would have used the optics, but the telescopes are similar to those described on Keyhole-class imaging satellites.
Loretta Desio, a spokesperson for the NRO, said the telescopes were constructed in the late 1990s and early 2000s.
The NRO called NASA officials in January 2011, saying it would make two telescopes available after they were no longer needed for their original intelligence missions.
"We just swapped a piece of paper and it became ours," said Michael Moore, acting deputy director of NASA's astrophysics division.
From the outside, Moore said, the optics resemble the foil-wrapped silver barrel of the Hubble Space Telescope. The telescopes have a 94-inch primary mirror - the same size as Hubble's - but its dimensions would allow instruments to see a broader swath of the sky at high resolution than NASA's famous observatory.
"It's about half the length of Hubble, so the mirror is polished much deeper," Moore said. "It looks much more like a bowl than a shallow dish. It's also a much lighter system. The state of the art moving forward has really made this a great piece of equipment."
Moore said the equipment is stored in Rochester, N.Y., at ITT Exelis, the telescope's manufacturer. Some of the components may need assembly.
NASA asked scientists to evaluate the optical telescope's suitability for the WFIRST mission, and the experts concluded the it was a good fit and would enable even better imaging than originally conceived for the next-generation observatory.
The $1.6 billion WFIRST mission was identified as the top priority for the next decade by astrophysicists in 2010, but NASA has not received enough funding to start development of the observatory, which aims to survey the cosmos to create a census of alien planets, study dark energy and chart the evolution of galaxies in the early universe.
Much of NASA's budget for astronomy and astrophysics is tied up in the James Webb Space Telescope, an over-budget $8.8 billion mission now scheduled for launch in October 2018. Until JWST's soaring development costs are behind it, NASA will not be able to start significant work on another large astrophysics mission.
Moore said it would cost "along the lines of" $250 million to build the optics for a mission of the class of WFIRST.
"There's still a lot of investment work and coordination that's required," Moore said. "On the upside, typically the longest and most difficult element in our program planning of our large telescopes has always been the optical system. And in this case, we simply don't have to spend any money on that."
The acquisition of the spy hardware will reduce the cost and development time of WFIRST, but it does not solve NASA's budget conundrum.
If NASA gets the funding it expects over the coming decade, the earliest plausible time WFIRST could be on the launch pad is 2024, according to Paul Hertz, director of NASA's astrophysics division.
NASA still needs a budget to design and build science instruments and a spacecraft to support the telescope, along with a launch vehicle to send it to an operating post in space.
The best-case scenario is a launch in 2019 or 2020, but that assumes "money is no object," Hertz said. "We have no reason to believe that will happen."
But Spergel said the availability of a qualified telescope makes the mission more likely to proceed into development and launch.
"Some of the things WFIRST is going to do are tricky, but I would say I'm optimistic at this point," said Alan Dressler, an astrophysicist at the Carnegie Institution of Washington who also reviewed the compatibility of the NRO spy telescope and WFIRST.
Scientists envisioned a 59-inch mirror on WFIRST. The primary mirror was sized to simplify development and construction of the mission's telescope section, reducing the project's overall cost.
But the 94-inch aperture on the NRO optical system will permit Hubble-class resolution over a wide field-of-view - imaging a swath of the sky 100 times larger than Hubble can see in a single exposure.
"The bigger aperture size gives you sharper images of galaxies and stars," Spergel said.
Not only would WFIRST's observations answer key questions about the expansion of the universe, dark energy and surveys for exoplanets, it might also find interesting targets for follow-up by JWST, which has a primary mirror nearly three times larger than Hubble and the spy telescope acquired from the NRO, according to Hertz.
Until NASA has money to do something with the NRO telescopes, it will cost the space agency up to $100,000 per year to maintain the sensitive hardware in a clean room.
"The two telescopes are identical, and we received them as a package deal from the NRO," Hertz said. "We don't, at this point in time, ever anticipate being rich enough to use both of them, but it sure would be fun to think about, wouldn't it?"