The Obama administration wants to keep the International Space Station flying until at least 2024, four years beyond a previous target.
The $100bn (£60bn) orbital research outpost is a joint project between 15 nations, but Nasa's costs for operating the station, which flies about 250 miles above Earth, run at about $3bn a year with about half that sum spent on transporting crew and cargo.
The proposed extension would give the US space agency more time to develop the technologies needed for eventual human missions to Mars, the long-term goal of Nasa's human space program, and would also open a window for commercial companies and researchers to benefit from hefty US investment in the outpost.
"Ten years from today is a pretty far-reaching, pretty strategic-looking vision," Nasa Associate Administrator Bill Gerstenmaier told reporters on a conference call yesterday.
"This extension opens up a large avenue of research on-board station. It also changes the perspective for the commercial (transportation) providers. Now they can see a market that extends to at least 2024.”
Construction of the orbital outpost began in 1998. The prime partners in the venture, with the USA, include Russia, Europe, Japan and Canada. It has been permanently staffed by rotating crews of astronauts and cosmonauts since 2000.
Extending the station "is not a US-only decision," Gerstenmaier said. "We talk to our partners about this. They want to go forward with this. It's just working through the government approval," he said. "We're prepared to do what we have to do if the partners choose to take a different path.”
A technical review by prime station contractor Boeing shows the station's laboratories, structural frame and other hardware are safe to fly until 2028, and program manager John Shannon said earlier yesterday at the opening of an international space exploration and policy summit.
"If the physical hardware continues to operate the way we believe it does ... that leaves the door open in the future to extend," Gerstenmaier said.
At the end of its life, the station will be steered down into the atmosphere, where it will incinerate as it re-enter over an ocean so any surviving debris will not threaten populated areas.