A draft NASA bill being considered by the House Science Committee does not provide for an extra space shuttle mission and undercuts a compromise forged last week between the White House and Senate.

The Ares 1 and Ares 5 rockets. Credit: NASA

The legislation calls for NASA to restructure its exploration program and develop a government-owned transportation system for U.S. astronauts by the end of 2015.

The committee posted an early version of its NASA Authorization Act of 2010 on the Internet late Monday night. The House Science Committee will hold a markup hearing on the legislation Thursday morning.

The House committee, chaired by Rep. Bart Gordon, D-Tenn., directs NASA to build upon $9 billion already invested in the Constellation program, which the White House proposed terminating in its February budget request for fiscal year 2011.

"In an environment of constrained budgets, responsible stewardship of taxpayer-provided resources makes it imperative that NASA's exploration program be carried out in a manner that builds on the investments made to date in the Orion, Ares 1 and heavy-lift projects," the draft bill says.

The draft bill also calls for NASA to develop a heavy-lift rocket by the end of this decade.

The White House, Senate and House policy guidelines all provide for a topline NASA budget of about $19 billion, but the similarities end there.

The House legislation goes further than the Senate authorization bill to undo the Obama administration's proposed overhaul of NASA's human space program.

The Senate bill was marked up in that body's commerce committee last week and presented as a compromise with the White House. An Obama administration spokesperson said the Senate bill "represents an important first step" in the NASA budget process.

Last week's Senate compromise would immediately fund the development of a government heavy-lift launch vehicle and crew capsule for deep space missions. But it also calls for $1.6 billion in funding for commercial crew projects over the next three years, about half of the White House's proposal.

The White House requested $3.3 billion in February for NASA to help pay for new privately-developed spacecraft to ferry astronauts to and from the International Space Station.

Monday's draft of the House authorization act only provides for $150 million in commercial crew funding during the same three-year period.

Unlike the Senate legislation, the House bill does not authorize an additional space shuttle mission to stock the space station with supplies. The Senate authorization act, which is still awaiting passage on the Senate floor, directs NASA to fly an extra shuttle flight next summer.

The Congressional authorization acts are just the first step in the budget process. Each body's appropriations committees must write legislation to provide funding to federal agencies.

Any differences in Senate and House bills must be resolved before heading to the president's desk.