Andrew Lawler Science 21 September 2007: Vol. 317. no. 5845, p. 1663 Supporters of the world's largest radio telescope in Arecibo, Puerto Rico, gathered last week in the shadow of the U.S. Capitol in hopes of keeping the observatory alive. But time is running short, and the advocates face an uphill struggle to keep the 40-year-old observatory, whose receiving dish extends 305 meters across a natural sinkhole, operating into the next decade. Last fall, the National Science Foundation (NSF) endorsed the recommendations of an independent panel to reduce the astronomy division's support for Arecibo from $8 million to $4 million to free up funds for new projects such as the Atacama Large Millimeter Array being built in Chile (Science, 10 November 2006, p. 904). All NSF funding for the telescope would cease after 2011 if outside donors can't be found, although the observatory's planetary radar could close as early as October 2009, says Robert Brown, director of the National Astronomy and Ionosphere Center (NAIC), based at Arecibo and operated by Cornell University. The radar is especially important for imaging planets such as Venus and computing exact trajectories of near-Earth objects that might pose a hazard. NASA decided in 2001 to halt funding for the radar, which now costs $1 million a year to operate, in order to focus on space-based observatories. Brown, who helped organize last week's meeting in Washington, D.C., argues that the independent panel's recommendations are outdated because their premise--that NSF's astronomy budget would remain static--now seems unlikely, given the strong political support for increased federal spending in the physical sciences. "The plan … should be rethought," he says. One New York legislator who sits on the powerful appropriations committee and is a leader of the Hispanic community is already convinced. "The Arecibo Observatory is an important scientific tool for our nation," says Representative José Serrano (D-NY). "I will be monitoring its funding situation and making sure that the correct decisions are being made." Serrano declined to say how and when he might push for more money. That appeal to Congress doesn't sit well with NSF officials. "We commissioned a panel to determine scientific priorities," says Wayne van Citters, who heads the agency's astronomy division. "To involve Congress in one aspect of it is not a productive way to go." Van Citters fears that legislators might shift money from newer, more promising projects. "We have to recognize [there are] limited funds," says Garth Illingworth, a University of California, Santa Cruz, astronomer at Lick Observatory, who also serves as chair of the Astronomy and Astrophysics Advisory Committee that advises NSF, NASA, and the Department of Energy. "Focusing on whole new wavelength areas may be more appropriate." One participant at the meeting, held in a building near the Capitol, complains that the NSF panel underestimated the importance of the radar. Steven Ostro, an astronomer at the Jet Propulsion Laboratory in Pasadena, California, says that Van Citters "effectively stonewalled" its advocates because its mission fell outside NSF's purview. But Van Citters says that NAIC and Cornell proposed to cut the radar to cope with the decreasing budget, without prodding from NSF. Brown says that the Puerto Rico government, private individuals, and commercial companies have expressed some interest in supporting the telescope's operations, including the radar. And although Van Citters says he's optimistic that a white knight will appear, he warns that any plan to keep Arecibo going "has to be sustainable."