As of September 2026, humanity has two continuously crewed space stations: China’s Tiangong, occupied without interruption since 2022, and the International Space Station. If the ISS retires around 2030 before replacement stations are ready, Tiangong could become the only permanently inhabited outpost in Earth orbit.

Two space stations currently sustain uninterrupted human occupation in Earth orbit. The International Space Station has the longer record, with crews living aboard since November 2000. China’s Tiangong began its continuous occupancy in June 2022. As of September 2026, the proposed commercial stations intended to follow the ISS have yet to establish a comparable operating record.

The risk is a break between the old station and its successors.

If the ISS ends crewed operations before another continuously inhabited station is ready, Tiangong could become the only such outpost orbiting Earth. The condition matters: this is a possible consequence of mismatched schedules, not an announced outcome. NASA is trying to preserve continuity, and the timing of ISS retirement remains subject to decisions about hardware, funding and the transition.

How Tiangong acquired an unbroken crew presence

The Chinese human spaceflight programme’s Shenzhou-14 mission record places the crew’s arrival inside the Tianhe core module on 5 June 2022. Chen Dong, Liu Yang and Cai Xuzhe entered that evening, beginning a six-month mission during which the station gained its Wentian and Mengtian laboratory modules.

The next rotation established the handover pattern. Shenzhou-15 arrived while Shenzhou-14 was still aboard, allowing the two crews to meet in orbit. The December 2022 account of Shenzhou-14’s return records that first handover and the temporary increase to six people on the station.

Overlapping expeditions allow one team to take responsibility before another leaves. Continuous occupation therefore describes a succession of residents, rather than any individual remaining indefinitely. China’s Shenzhou-23 mission page records another crew meeting in May 2026, part of that continuing sequence.

SpaceDaily has previously examined the separate development paths of Tiangong and the ISS. Here, the narrower issue is operational: which stations will have people living aboard without a break when the existing international laboratory finishes its work?

Why 2030 is a planning date

NASA’s ISS transition explanation sets out its commitment to operate the station through 2030. It also identifies a physical limit to extensions: the lifetime of the primary structure, including modules and trusses, which experiences stresses from visiting spacecraft and repeated heating and cooling in orbit.

The station cannot simply be maintained forever by replacing small components. Its eventual retirement requires a controlled disposal operation, with the crew returning before the final manoeuvres that direct re-entry towards a remote ocean area.

But an operating commitment through 2030 is not a guarantee of a particular final departure day. The date at which the last residents leave is also distinct from the date the empty station re-enters. For the question of continuous habitation, the former is the relevant milestone.

There are political efforts to allow more time. In March, the US Senate Commerce Committee advanced legislation proposing an extension to September 2032, with a transition tied to a commercial station demonstrating the required capabilities. Committee passage records a legislative proposal; it does not by itself establish a revised operational retirement date.

NASA’s replacement strategy still requires working stations

NASA’s intended successor arrangement changes ownership as well as hardware. The agency wants to purchase services from commercial operators, with other customers helping support those businesses. Its commercial station programme includes several development approaches, including Axiom’s plan to attach commercial modules to the ISS before establishing an independent station.

On 6 July 2026, NASA released a draft request for proposals for the next phase. The agency described an approach supporting development, certification and services, with two or more contractors potentially selected for early development and later competition for further work.

NASA also reported industry’s confidence that the timelines and a commercial market were achievable. That is the industry’s assessment, conveyed by the agency. The draft solicitation itself did not demonstrate an operational replacement.

Reaching routine service requires several separate accomplishments: completing hardware, testing it, launching it, proving its systems in orbit and securing approval for the intended crew operations. A successful launch would advance a project substantially while leaving further work before regular occupation could begin.

A visited station is different from an inhabited one

Commercial stations need not all begin with a permanent resident crew. Vast’s Haven-1 programme page, for example, advertises two-week missions and targets launch in 2027. Those are company plans, and a short visit would be a different operating pattern from Tiangong’s overlapping expeditions.

A station could consequently be functioning, hosting experiments and receiving occasional astronauts without maintaining uninterrupted occupation. Saying Tiangong might become the only permanently inhabited outpost does not mean it would necessarily be the only station in orbit, or that nobody else could make an orbital flight.

That distinction makes launch dates alone an incomplete way to judge the transition. The relevant evidence will include the duration of crew stays, the interval between them and whether routine rotations are actually sustained.

The milestones that will resolve the question

A continuity gap can be avoided if a successor establishes sustained occupation before the ISS’s final crew departs, or if the ISS remains safely operational until that happens. Neither route can be assessed solely from a proposed calendar.

The next useful markers are concrete: commercial hardware completing tests, certification decisions, crewed operations and firm arrangements for subsequent rotations. Alongside those, the ISS partners’ operating decisions will determine how much overlap is available. Those milestones will show whether a handover is taking shape while both existing stations still have crews aboard.

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