Twenty years after astronauts moved in full time, the International Space Station is nearing its end, opening up a new geopolitical landscape above Earth.Why it matters: The end of the program will force nations collaborating on the station, along with China and others new to the human spaceflight scene, to recalibrate. They could also turn their attention to cooperating — or competing — on the Moon instead.The state of play: The U.S. could end its support of the space station at the end of 2024, but NASA and its partners are considering extending its life until 2028.Either way, countries involved in the ISS program are already pivoting to collaborate on NASA's Artemis Moon mission, which is expected to bring people to the lunar surface by 2024. The European Space Agency signed on last week to help build the small Gateway space station that will orbit the Moon and act as a jumping-off point for missions to the surface.Japan and Canada, nations that also collaborate on the ISS, are working on Gateway as well.The intrigue: The space station has been a constant in orbit, tying the U.S., Russia and about a dozen other countries together in their space ambitions.But the end of the ISS could pull the U.S. and Russia away from one another.It's not yet clear where Russia — one of the largest supporters of the ISS — will land when it comes to post-space station cooperation. Dmitry Rogozin, the head of Russia's space agency Roscosmos, has already spoken out against the Gateway station, calling the Artemis Moon plans too "U.S. centric."Between the lines: Another wrinkle in the post-ISS geopolitical landscape is China's ambition to build its own station orbiting Earth, which is expected to come online around the time the ISS ends.That could pull possible U.S. partners in space to China instead, with some experts suggesting Russia might find new ways to collaborate with China. "I don't think Russia and China are immediately going to become best buddies. ... They've got their own complications in their relationship, but it does provide an alternative and a different option for countries that might not have been able to get on board with the U.S., Russia and the current ISS," Victoria Samson of the Secure World Foundation told me. The big picture: Not all attention will turn to the Moon at the end of the space station, however. NASA is hoping to make use of private space stations under development as a proving ground for missions to deeper space.Those space stations could be places where nations are able to collaborate with one another as well."My guess would be the international partners would be buying time on those commercial vehicles," former NASA administrator Charles Bolden told me.Yes, but: In order to smoothly transition between the ISS and these private stations, companies would need to have them operational in orbit before the end of the space station, an aggressive timeline that may not be met.The bottom line: Geopolitics are shifting in space as the ISS winds down and nations start to look to the Moon as a place for collaboration.