ESA reserve astronaut John McFall has been selected for the first crew of Haven-1, a commercial space station built by the US company Vast, and is on track to become the first physically disabled person in space. The mission, targeted for early 2027, will last roughly 30 days and is designed to answer a question that has never been systematically tested: does a lower-limb disability matter in microgravity?
McFall, 45, is a British surgeon and former Paralympic sprinter who lost his right leg above the knee in a motorcycle accident at age 19. He won a bronze medal in the 100-metre sprint at the 2008 Beijing Paralympics before training as an orthopaedic surgeon. In 2022 he was selected for ESA’s Fly! feasibility study, which aimed to determine whether someone with a physical disability could safely live and work in space. The study concluded in February 2025 with a clearance for long-duration spaceflight.
“We couldn’t really think of a disadvantage other than maybe having to work slightly harder,” McFall told Live Science in an interview published June 16.
The question at the heart of the mission is deceptively simple: do you need both legs to stabilize yourself in microgravity while your hands are busy doing tasks? On Earth, the answer is clearly yes — lower limbs provide a stable base for fine motor work. In orbit, where nothing weighs anything and you float rather than stand, the answer is unknown. McFall will spend his 30 days on Haven-1 running experiments designed to find out.
McFall’s physiology may confer unexpected benefits in space. The most striking is spaceflight-associated neuro-ocular syndrome (SANS), a condition affecting 70 to 75% of astronauts that causes fluid pressure changes behind the eye, leading to vision problems. Because McFall has less lower-limb fluid volume than an able-bodied astronaut, the fluid shift toward his head on entering microgravity may be proportionally smaller, potentially reducing pressure on the optic nerve.
He may also face a lower risk of kidney stones. Bone resorption in microgravity releases calcium into the bloodstream, which can crystallize in the kidneys. With lower overall bone mass, McFall may excrete less calcium.
These are hypotheses. Confirming them will require in-orbit urine samples, blood draws, and eye examinations — precisely the kind of data the mission aims to collect.
A Prosthesis Designed for Space
McFall will wear a prosthetic leg during the mission, particularly for launch and potential emergency egress scenarios. The design is modular: a socket worn at all times, with a quick-change adapter that allows the foot to be attached or removed as needed. The hardware is commercial off-the-shelf, modified for space with fireproof tape around certain components, less-toxic hydraulic fluids, and a redesigned foot shape for better interaction with handrails and straps.
The socket interface between the prosthesis and McFall’s residual limb is being redesigned for the mission, with potential benefits for lower-limb amputees on Earth. The quick-change adapter, optimized for the unique demands of space, could also translate directly to improved prosthetic technology.
A Mission Beyond the Self
McFall is conscious of the broader meaning of his selection. “To me personally, it doesn’t make a difference,” he said. “However, I am very aware that the broader message that it sends to wider society about what people are capable of — whether they have a disability or not — is very interesting and powerful.”
He is already looking beyond the 30-day mission. “I would love to, in the future, potentially spend longer in space, demonstrating that it’s possible for someone with a disability to live and work in space,” he said. “And absolutely, I would love to go to the moon. Someone with a lower-limb disability, when you propose that against walking on the moon, it’s quite a powerful statement, and I would love to do that.”
Source: Baker H. ‘Is having two legs useful’ in space?: Astronaut John McFall explains what life in orbit might be like for the first physically disabled person in space. Live Science. 16 June 2026. https://www.livescience.com/space/space-exploration/is-having-two-legs-useful-in-space-astronaut-john-mcfall-explains-what-life-in-orbit-might-be-like-for-the-first-physically-disabled-person-in-space