President Obama's plan for NASA—or at least a modified version of it—cleared a major hurdle late on Sept. 29, when the House of Representatives agreed to the Senate's version of a three-year authorization bill for the space agency. The legislation would add one space shuttle flight to the docket, raising the total number of remaining shuttle missions to three, and would pave the way for commercial operators to return astronauts to orbit once the shuttle is retired in 2011.

The bill, which Obama is expected to sign, lays out authorized expenditures for fiscal years 2011, 2012 and 2013, but the actual funds allocated to the agency will depend on later appropriations legislation.

In his February budget request, Obama proposed sweeping changes to the way NASA does business, essentially scrapping the agency's prior objectives of building a new set of rockets and space hardware to deliver astronauts to low-Earth orbit and then the moon. Instead, the president's plan called for delegating the development of low-Earth orbit services to the private sector. Having endured criticism for omitting details on where, if not the moon, astronauts would be headed, and on what time frame, the president announced in April that an unprecedented visit to a nearby asteroid would be the first destination, perhaps as early as the 2020s, followed by a manned mission to Mars in the 2030s.

The Senate passed its authorization bill, which matched the $19 billion that Obama had requested for NASA in fiscal year 2011, on Aug. 5. The bill authorized $612 million to develop commercial crew and cargo services in 2011, as well as $500 million for commercial crew development in both 2012 and 2013. But a very different House bill that was introduced in July offered a much smaller commitment to the private sector—only $64 million for 2011—and proposed devoting the bulk of NASA's exploration budget to essentially reviving the family of Ares rockets that Obama sought to cancel.

The triumph of the Senate authorization bill over the House version is good news for private spaceflight companies such as SpaceX, who could step into the void left by the shuttle's retirement to ferry astronauts to orbit. "The bill sets NASA on an exciting course to focus on exploration beyond low-Earth orbit, while recognizing the valuable role American companies are ready to undertake in ending our reliance on Russia to carry our astronauts to the International Space Station," SpaceX CEO Elon Musk said in a prepared statement.

The Senate version hardly puts NASA out of the rocket business, however. In 2011 alone, the authorization bill budgets $1.1 billion dollars to continue developing the Orion space capsule that was originally intended to launch atop Ares rockets and $1.6 billon to develop a vehicle called the Space Launch System to boost astronauts beyond low-Earth orbit. The bill cleared the House by a vote of 304–118 at 11:36 P.M., toward the end of a marathon legislative day as the House prepared to adjourn until November 15, after the fall elections.

"As you can imagine, we're thrilled to have this three-year authorization bill," NASA deputy administrator Lori Garver said in a teleconference with reporters Sept. 30, calling the bipartisan Congressional support a resounding vote of confidence in the agency. "I think it's clear that our space program inspires passion across party lines," Garver said.

The extra shuttle flight, which would launch no earlier than June 2011, would be used to resupply the International Space Station with hardware to extend its usability. "We have a space station where we're all getting complacent on how well it's operating," Garver said. "We'd love to put additional spares up on the space station."

That Congress took action and green-lit a sizable budget for NASA is a good thing, says Jim Bell, a Cornell University planetary scientist and president of the nonprofit Planetary Society. On balance, Bell says, the legislation appears to be a step in the right direction, laying out a healthy program of Earth science, robotic exploration and technology development, among other things. "On the flip side, we're a little disappointed in the rather tepid or backhanded support for the new proposed human spaceflight program," Bell says. "We were solidly behind the administration's original proposal," he adds, which was more focused on commercial investment and research and development of new technologies for human spaceflight.

The plan authorized by Congress is more aligned with existing technology. The bill stipulates that the Space Launch System be based on shuttle- and Ares-derived components wherever possible and specifies performance metrics for the vehicle. "It seems like Congress is going in and trying to build a rocket. And so that's a little unfortunate that the bill is so specific and prescriptive," Bell says. "We'd really like NASA to focus on exploration rather than transportation."