The US astronaut Mark Vande Hei has made it through nearly a year in space, but now faces what could be his trickiest assignment: riding a Russian capsule back to Earth in the midst of deepening tension between the two countries. Nasa insists Vande Hei’s homecoming at the end of the month remains unchanged, even as Russia’s invasion of Ukraine has resulted in canceled launches, broken contracts and an escalating war of words from the leader of the Russian Space Agency. Many worry Dmitry Rogozin is putting decades of peaceful partnership at risk, most notably at the International Space Station (ISS). Vande Hei, who on Tuesday will break the US single spaceflight record of 340 days, is due to leave with two Russians aboard a Soyuz capsule for touchdown in Kazakhstan on 30 March. He will have logged 355 days in space. The world record of 438 days belongs to Russia. The retired Nasa astronaut Scott Kelly, America’s record-holder until Tuesday, is among those sparring with Rogozin, a longtime ally of Vladimir Putin. Kelly has returned a medal to the Russian embassy in Washington but believes the two sides “can hold it together” in space. “We need an example set that two countries that historically have not been on the most friendly of terms, can still work somewhere peacefully. And that somewhere is the International Space Station. That’s why we need to fight to keep it,” Kelly said. Nasa wants to keep the space station running until 2030, as do the European, Japanese and Canadian space agencies. The Russians have not committed beyond the original end date of 2024 or so. The US and Russia are the prime operators of the orbiting outpost, permanently occupied for 21 years. Until SpaceX started launching astronauts in 2020, Americans hitched rides on Russian Soyuz capsules for tens of millions of dollars a seat. The US and Russian space agencies are still working on a system in which a Russian would launch on a SpaceX capsule beginning this fall and an American would fly on the Soyuz, helping ensure a US and Russian station presence at all times. Vande Hei, 55, and a retired army colonel, moved into the ISS last April, launching on a Soyuz from Kazakhstan with Pyotr Dubrov and another Russian. He and Dubrov stayed twice as long as usual to accommodate a Russian film crew in October. As the situation 260 miles below intensified last month, Vande Hei acknowledged he was avoiding conversations about Ukraine with Dubrov and Anton Shkaplerov, their Russian commander. Three more Russians will blast off from Kazakhstan on Friday. “We haven’t talked about that too much. I’m not sure we really want to go there,” Vande Hei told an interviewer. “It would be a sad day for international operations if we can’t continue to peacefully operate in space,” said the Nasa human spaceflight chief, Kathy Lueders, who noted it would be “very difficult” to go it alone. SpaceX is taking three businessmen and an ex-astronaut escort to the space station at the end of March. In mid-April, SpaceX will deliver four astronauts for Nasa before bringing back four on board since November. Nasa and SpaceX refuse to speculate on whether a seat could be made available for Vande Hei. They say a Nasa plane and small team will be in Kazakhstan, as usual, to whisk him back to Houston. A former Nasa astronaut, Heidemarie Stefanyshyn-Piper, whose father was born in Ukraine, said it was a difficult situation. “We’re sanctioning Russia. Companies are pulling out of doing business in Russia. But then yet you still have the US government, the space agency, doing business with the Russians,” she said. “You can’t push a button and separate the two” sides of the space station. Besides threatening to pull out of the space station and drop it on the US, Europe or elsewhere, Rogozin had flags of other countries covered on a Soyuz rocket awaiting liftoff earlier this month. The launch was called off after the customer, London-based OneWeb, refused his demands that the satellites not be used for military purposes and the British government halt financial backing. The European Space Agency is reeling. After missing a 2020 launch deadline for its Mars rover, a European-Russian effort, the project was on track for a September liftoff from Kazakhstan. Now it’s most likely off until 2024, the next opportunity for Earth and Mars to be properly aligned. Russia has pulled staff out of the French-run launch site in South America, suspending Soyuz launches of European satellites. All this comes on top of a Russian anti-satellite missile test in November that added junk to debris encircling Earth and put the space station’s four Americans, two Russians and one German on alert for days. Jeffrey Manber, now with the private Voyager Space company, helped forge US and Russian ties in the mid-1990s. He sees the space station as “one of the final holdouts of collaboration”. But, he added, “there is no going back if the partnership is ended and the result is a premature ending of the ISS program”. John Logsdon, professor emeritus at George Washington University, expects the end of large-scale space cooperation between Russia and the west. “Russia has been moving toward China already, and the current situation will probably accelerate that move,” he said.