What's Going to Happen to the International Space Station?

American astronaut Clay Anderson waving during a spacewalk outside the International Space Station.

American astronaut Clay Anderson waving during a spacewalk outside the International Space Station. NASA/AP

Russia plans to kick Americans off the station after 2020, four years earlier than the space mission's intended end.

Russian Deputy Prime Minister Dmitry Rogozin said Tuesday that, in response to American sanctions imposed after its annexation of Crimea, his country would ban the United States from the International Space Station after 2020.

"The Russian segment can exist independently from the American one," he said. "The U.S. one cannot."

Rogozin has a point, and it's one that puts the future of U.S. spaceflight in question. While the station is manned by an American and Russian (and Japanese and Canadian) crew, the only way to get there is on Russian Soyuz spacecraft. NASA pays Russia $70.7 million per trip to ferry its astronauts to and from the station. While Russiadepends on NASA's electronics and communications technology, which are more advanced, transportation trumps tech out there.

Rogozin's remarks may also be no more than political posturing. NASA officials say the agency has not received any official notification from Russia about changes in cooperation. It's business as usual at the station right now: Three astronauts—American, Russian and Japanese—returned to earth from the station on Wednesday after more than six months working together in space. Two Russians and one American remain, and a new batch of astronauts is expected to launch in a few weeks.

Clara Moskowitz at Scientific American points out that talk about cutting ties with the U.S. came from a Russian politician, rather than an official at Roscosmos, Russia's space agency, or the country's scientific community. "At the political level, people are starting to huff and puff," space policy expert Roger Handberg of the University of Central Florida told Moskowitz. "But at the agency level, they're trying to keep it calm because they understand they're tied together at this point."

In January, the Obama administration extended the ISS mission, scheduled to end in 2017, until 2024. In March, when the Ukraine crisis began in earnest, the idea that political tension would affect one of humanity's greatest achievements was hard to believe. Back then, NASA was "confident that our two space agencies will continue to work closely as they have throughout various ups and downs of the broader U.S.-Russia relationship," a spokesman for the agency said. After all, NASA's relationship with Roscomos had previously withstood the conflict in Syria and Russia's protection of NSA whistle-blower Edward Snowden.

The rosy picture of collaboration has soured since then. In early April, NASA suspended contact with Russian government representatives, citing the country's "ongoing violation of Ukraine's sovereignty and territorial integrity." At the time, operations aboard the ISS were exempt from the suspension. Now the future of those operations is in doubt.

That kind of talk is enough to change the situation on the ground even as cooperation continues in space. Russia's threat of kicking U.S. astronauts off ISS could add more fuel to NASA's partnership with private American spaceflight companies, who are working to launch astronauts from American soil by 2017. U.S. lawmakers have long called for ending American dependence on Russian space transport, and the recent threats from Moscow could rally support in Washington.

Weakened ties with Russia could also mean that one of America's biggest political rivals on earth could become its biggest ally in space. China is not part of the ISS mission, in part because of U.S. opposition, but it recently successfully transported crew to and from a Chinese space station.

"China is an obvious addition to the international [human spaceflight] partnership, both for the ISS program and beyond," Leroy Chiao, a former NASA astronaut, told the Senate Science and Space Subcommittee last month.

So don't worry, Russia's ban does not mean the ISS is going to plummet into the ocean anytime soon. It does, however, mean that even space is no longer immune to politics.