President Donald Trump wants to end US funding for the International Space Station (ISS) by 2025 with the aim of putting it into private hands.
His plans for ISS and the Nasa space programme were unveiled in his 2019 budget proposal. Mr Trump wants to increase Nasa spending by 3% next year.
But it also includes $150m (£108m) to "encourage commercial development" at ISS to replace American payments.
The space station is scheduled to operate through 2024.
"The budget proposes to end direct US financial support for the International Space Station in 2025, after which NASA would rely on commercial partners for its low Earth orbit research and technology demonstration requirements," according to the White House proposal, which was released on Monday.
The US government would create a $150m programme to help prepare private companies to take over space station operations over the next seven years, according to the document.
The budget requests $19.6bn for Nasa in 2019, an increase of $500m from this year.
It also calls for $10.5bn for "an innovative and sustainable campaign of exploration" leading to "the return of humans to the moon for long-term exploration and utilization followed by human missions to Mars and other destinations", according to a Nasa review.
Robert Lightfoot, NASA's acting administrator, called it a "pretty exciting time" for the agency.
"It really reflects the administration's confidence that America will lead the way back to the moon and take that next giant leap from where we made the first small step for humanity some 50 years ago," he said, reports BBC.
Democratic Senator Bill Nelson, a former astronaut, said the proposed plan to stop funding the International Space Station "makes no sense".