The safe return of the Shenzhou-20 crew this past Friday brought an end to the longest single stay in orbit for any Chinese crew. The crew landed at the Dongfeng landing site in north China’s Inner Mongolia Autonomous Region, ending their 204-day mission. Yet, that successful homecoming immediately ushered in a new, albeit temporary, crisis.

While the three taikonauts touched down safely on Friday, they left their replacements — the Shenzhou-21 crew — marooned aboard the Tiangong Space Station, with no ride home in the event of an emergency.