China's Tiangong Could Become the Only Continuously Crewed Space Station If ISS Retires First

As of September 2026, two space stations have continuously housed crews for years: the International Space Station (ISS), inhabited without interruption since November 2000, and China's Tiangong, continuously occupied since June 2022. NASA has committed to operating the ISS through 2030, but no commercial successor station has yet matched that operating record. If the ISS ends crewed operations before a successor achieves continuous occupancy, Tiangong could become the only such outpost in orbit — a possible consequence of mismatched schedules, not an announced outcome.

Tiangong's continuous crew presence began on 5 June 2022, when Shenzhou-14 astronauts Chen Dong, Liu Yang and Cai Xuzhe entered the station's Tianhe core module for a six-month mission, during which the Wentian and Mengtian laboratory modules were added. Shenzhou-15 arrived that December while Shenzhou-14 was still aboard, briefly raising the crew to six and establishing a handover pattern that has continued through missions including Shenzhou-23 in May 2026.

NASA says the ISS cannot be extended indefinitely: its primary structure, including modules and trusses, faces physical limits from the repeated stresses of visiting spacecraft and orbital heating and cooling. Eventual retirement will require a controlled disposal operation, with the crew returning to Earth before the station is directed toward re-entry over a remote ocean area. An operating commitment through 2030 does not guarantee a specific departure date for the crew.

NASA's replacement strategy involves purchasing services from commercial operators rather than owning the hardware itself. On 6 July 2026, the agency released a draft request for proposals for the next development phase, describing an approach with two or more contractors potentially selected for early development. Commercial concepts include Axiom's plan to attach modules to the ISS before operating independently, and Vast's Haven-1 programme, which advertises shorter, roughly two-week missions targeting a 2027 launch rather than continuous occupancy.

Whether a continuity gap actually occurs depends on concrete milestones still to come: commercial hardware completing tests, certification decisions, crewed operations beginning, and whether rotations are sustained without a break.