WASHINGTON — House lawmakers have introduced legislation authorizing three additional space shuttle flights before the fleet's scheduled 2010 retirement, including the launch of a science probe removed from the manifest after the 2003 Columbia accident.

The proposed NASA Authorization Act of 2008 designates $150 million for a space shuttle flight to deliver the Alpha Magnetic Spectrometer (AMS) to the International Space Station in 2010.

Two other flights that NASA already has budgeted for and placed on its manifest as contingencies while awaiting White House approval would become part of the official manifest under the bill introduced last week by Rep. Mark Udall (D-Colo.), chairman of the House Science and Technology space and aeronautics subcommittee, ranking minority member Rep. Tom Feeney (R-Fla.), and Reps. Ralph Hall (R-Texas) and Bart Gordon (D-Tenn.).

The Senate Commerce Committee has not yet introduced its version of the bill, and Congress still must appropriate the money needed to add the shuttle mission to deliver the AMS.

The AMS is a U.S. Department of Energy-led experiment, with 16 international partners, to measure charged particles outside Earth's atmosphere. NASA agreed in 1995 to launch AMS aboard a space shuttle to the space station, but constraints resulting from the Columbia accident, including a two-and-a-half year suspension of flights, pushed AMS off the manifest.

The experiment has wide support from members of Congress, who frequently have asked NASA to try and find a way to fit AMS in. In the bill that funded NASA for this year, Congress directed the agency to study the matter.

NASA responded in a February report to the House and Senate appropriations committees that the two contingency flights are fully loaded with large spare parts that only the shuttle can transport to the space station. Adding a space shuttle flight in 2010 would cost between $300 million and $400 million, the report said, and keeping the space shuttle flying in 2011 would cost between $2.7 billion and $4 billion.

"In summary, the existing space shuttle flight schedule, and potentially up to two contingency logistics flights, may be achievable before the [space shuttle's September] 2010 retirement. However, the program does not have a significant amount of margin to accommodate an additional flight for AMS without significant impacts to future exploration goals, cost, and possibly safety," the report said.

The authorization bill sets a $19.2 billion NASA budget for 2009, a $1.9 million increase over 2008. In addition to that figure, the bill seeks $1 billion to accelerate NASA's space shuttle replacement vehicles: the Orion crew capsule and Ares 1 rocket. NASA officials have said they could speed development of those vehicles by about two years — to 2013 — with an additional $2 billion.

The bill also extends the possibility of U.S. participation in the international space station for four additional years by directing NASA to "take no steps" that would prevent the United States from utilizing the space station after 2016.