One year after a controversial recommendation to cancel its National Science Foundation (NSF) funding, the Green Bank Telescope in West Virginia, the world’s largest fully steerable radio telescope, is searching for new partners to help support its $10-million annual operating costs. In the face of these potentially life-threatening cuts, some additional sources of revenue have been found—but the big telescope’s future still hangs in the balance.

In August 2012 the NSF's Division of Astronomical Sciences Portfolio Review Committee issued a report (pdf) that suggested divesting the Green Bank Telescope (GBT) by 2017. The report, "Advancing Astronomy in the Coming Decade: Opportunities and Challenges," has been controversial: both the NSF’s National Radio Astronomy Observatory and the NANOGrav Collaboration (which uses GBT as one of its telescopes to observe pulsars to detect gravitational waves) issued responses, and a public comment forum filled with debate over the telescope’s future.

The uproar was inspired by the telescope’s capabilities. The GBT features a steerable 100- by 110-meter elliptical radio dish, making it the largest of its kind in the world followed by the slightly smaller 100-meter Radio Telescope Effelsberg in Germany and the 76-meter Lovell Telescope in England. The sheer size of the GBT’s collecting area allows it to detect faint radio waves from distant celestial objects. The steerable nature of the dish gives it vision of an unprecedented 80 percent of the sky, making it versatile for several types of research such as astronomy, astrochemistry and astrophysics. More recently, the telescope has been involved in the search for intelligent life.

The observatory offers “a level of sensitivity you simply cannot get with any other telescope in the world,” says Karen O’Neil, GBT site director. The telescope also grants thousands of hours of open-access time per year, giving researchers an opportunity to work with state-of-the-art equipment. Now that the GBT is searching for funding partners, this open-access time is likely to disappear, as the partners will own the operating time. “There’s a lot of concern in what effect that's going to have on the astronomical community,” O’Neil says.

Individual researchers using the telescope are concerned as well, such as West Virginia University researcher Maura McLaughlin. She studies gravitational waves around pulsars, superdense neuron stars that litter the galaxy. The GBT is the best telescope for her research, she says. “The number-one thing is having a large collecting area [on the telescope,]” she says. “The GBT also has great laboratories on site—they really have the best pulsar ‘back end’ in the world. If we didn’t have the GBT, our research would really suffer.”

The suggestion to divest the GBT (among other sites) was not an easy one to make, says Daniel Eisenstein, a Harvard University astronomer and chair of the Portfolio Review Committee that issued the recommendation. The committee’s ideas, he says, were aimed at achieving a balance of scientific priorities against available funds: The NSF needs to achieve its strategic goals while managing funding for building new construction, running current facilities and supporting grant applications for research. "We were asked to construct portfolios that would maximize return across all areas of astronomical research, and to do so in a cost-controlled budget scenario," he adds. "This involves making hard choices."

Maintaining one of NSF’s goals of funding competitive research grants was a major priority. "We felt it was important to maintain money in the grants program," Eisenstein says. "This would allow the community to respond quickly to, and develop the next generation of, scientific opportunities."

Even in the face of budget changes GBT researchers and supporters remain optimistic. In July the Senate Committee on Appropriations approved the NSF's fiscal year 2014 funding, providing the agency with $7.426 billion, representing an increase of $542 million over the FY 2013 budget, but $200 million below the original request. The budget did not call for divestment of the GBT in FY 2014.

Also, some partners for the GBT have been found, including West Virginia University, which announced last week that it will dedicate $1 million to the telescope over the next two years. Whereas it only covers a fraction of the yearly operating cost, this partnership will give students and professors exclusive access to the GBT. “Because of this, we can use it for student projects that are exciting but necessarily not mainstream,” McLaughlin says. “I think there are enough universities that use the GBT that others will step up and help funding.”

O’Neil declined to disclose which or how many partners have been found to date, and it will be another year before the NSF has to draft its next budget and reconsider divesting the GBT. Until then, the long-term future of the GBT remains beyond our field of view.