WASHINGTON — Under a proposed amendment to the Senate’s defense authorization bill, U.S. commercial launch companies would retain their current liability shield and NASA would be allowed to keep trading with Russia to support the international space station — provided that Congress also agrees to a minimum funding guarantee for NASA’s Space Launch System (SLS) heavy-lift rocket.

The amendment was proposed by Sen. Kay Bailey Hutchison on Nov. 28 as the Senate resumed debate on the 2013 National Defense Authorization Act (S. 3254). Hutchison, the amendment’s sole sponsor, did not run for re-election in November and is ending her 24-year Senate career in January. She has been a fierce advocate for NASA’s human spaceflight program and for the Johnson Space Center in Houston.

A separate amendment to the bill, proposed by Sen. Michael Bennet (D-Colo.), would set the stage for easing export restrictions on U.S.-built satellites and related components, which for more than a decade have been regulated as highly sensitive military technology. Bennet’s amendment is co-sponsored by Sens. Marco Rubio (R-Fla.) and Mark Warner (D-Va.) and includes language that differs from a passage in the House’s defense authorization bill, which passed in May. Industry and government sources say the Bennet amendment is intended to mollify White House objections to portions of the House-passed language, including what some administration officials have characterized as onerous reporting requirements.

The Senate continued to debate the bill Nov. 29. While Congress is not bound by law to pass a defense authorization bill each year, lawmakers have historically done so, making the bill an attractive vehicle for amendments. Authorization bills set spending limits for federal programs but provide no actual funding, making them de facto statements of congressional policy.

Under Hutchison’s amendment, SLS, its companion Orion crew capsule and supporting ground infrastructure would be required to receive the same proportion of NASA’s human spaceflight budget in 2014 and 2015 as they get in 2013.

It is not yet known how much funding these programs will receive in 2013; the government is currently operating under a temporary spending measure that has frozen funding at 2012 levels through March. For 2012, Congress appropriated about $3 billion for SLS, Orion and related ground support systems. The 2013 federal budget is also still at risk of deep, automatic across-the-board cuts that would shave $1.5 billion off NASA’s top line unless Congress acts by Jan. 2 to avert what is known as sequestration.

Meanwhile, Hutchison’s proposal would also extend the U.S. government’s commercial space launch indemnity regime, under which taxpayers assume liability for launch-related damages that exceed a $500 million, through 2014. The House approved the same extension Nov. 14 in a stand-alone bill.

Finally, Hutchison proposed extending NASA’s waiver to provisions in the Iran, North Korea and Syria Nonproliferation Act that bar the agency from buying space station-related goods and services from Russia. Senior NASA officials have said they need this waiver to keep the $100 billion international space station in orbit. Hutchison’s amendment would let NASA trade with Russia through Dec. 31, 2021. The waiver is currently set to expire on July 1, 2016.

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...