The U.S. House of Representatives, which had proposed terminating NASA's next-generation space telescope, voted today to reverse course and fund the massive project. The James Webb Space Telescope, designed to succeed the Hubble Space Telescope as NASA's primary orbital observatory, would receive $529.6 million for the fiscal year ending September 30, 2012, under the new plan.

In July the House subcommittee responsible for NASA's funding released its draft budget, which would have eliminated the Webb telescope, or JWST, noting that it was over-budget by billions of dollars and claiming that the project was "plagued by poor management." But the Senate wrote into its budget more than half a billion dollars to keep JWST on track for a 2018 launch. (That timeline has slipped considerably during the telescope's development; the planned launch date was 2014 as recently as 2010.)

Today the House passed a compromise version of the appropriations legislation which funds NASA and several other government agencies by a vote of 298–121. The compromise, or conference report, included the Senate's full funding request for JWST. Hours later the Senate signed off as well by a vote of 70–30.

"It's certainly a major improvement in our position," says NASA's John Mather, senior project scientist for JWST and winner of the 2006 Nobel Prize in Physics. "Especially considering that not too many months ago one of the subcommittees voted to give us zero dollars."

Overall the budget bill grants NASA $17.8 billion, a decrease of more than half a billion dollars from last year's levels. The latest JWST cost estimates, which exceed $8.8 billion over the entire course of the project, mean NASA will have to cut back elsewhere. The agency's budget, as detailed in the conference report (pdf), includes reductions from what President Obama had requested for Earth and planetary science, astrophysics and institutional management—all to accommodate JWST. The appropriations legislation also includes $1.2 billion to continue developing the Orion crew capsule, as well as $1.86 billion to work on a congressionally mandated heavy-lift rocket called the Space Launch System.

The estimated cost and launch date of JWST have been moving targets, but advocates have stressed that the telescope is on solid ground technologically. "All 18 of the primary mirror segments have been polished and tested, and we're very happy with them," Mather says. "The parts that were the hardest ones have been finished."

If JWST can keep dodging legislative cost-cutting and finally take flight toward the end of the decade, it will take up a position well beyond the orbit of the moon to peer deeper into the universe than ever before with a giant, 6.5-meter mirror designed to corral faint infrared light. "The telescope does something that no one could ever tackle before," Mather says. "There's no competition in the past and there's nothing planned for the future, as far as I know. It's unique, it's irreplaceable, it's the only one."