27/05/2025
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The performance of a lower limb prosthesis has been evaluated in microgravity conditions for the first time during the latest ESA parabolic flight campaign on the ‘Zero G’ aircraft.
European Space Agency astronaut reserve John McFall tested his prosthetic hardware in microgravity by squatting, walking and running on a treadmill. The team assessed the performance of the prosthetic hardware in repeated periods of microgravity during over 90 parabolas across 3 flights.
The 86th ESA parabolic flight campaign took off on 21 May 2025 from Bordeaux, France.
John is a through-knee amputee who serves as a subject matter expert in ESA’s Fly! study. This groundbreaking initiative aims to understand and overcome the operational barriers that have historically prevented a lower limb amputee taking part in a long-duration mission to the International Space Station.
Making prosthetics ready for space
John uses a “smart” mechatronic knee with a prosthetic foot for everyday activities like walking and cycling, and a mechanical knee and prosthetic blade for running. The mechatronic knee combines mechanics, electronics and a range of sensors to control how the leg functions. Some of these sensors rely on gravity to work.
The Fly! research team designed the Ampu-T2 experiment to find out exactly how the mechatronic knee behaves in microgravity, and to determine the best setup of the prosthesis for running on a treadmill in space.
The Fly! team is working closely with Ottobock, a global leader in orthopedic technology, to collect data and fine-tune the performance of the prostheses for microgravity conditions.
Parabolic flights create short windows of microgravity by flying an aircraft in a curved trajectory called a parabola. During each of the 31 parabolas per flight, John and the team experienced 22 seconds of weightlessness, simulating the conditions on the International Space Station.
During the first flight, John squatted, walked and jogged in microgravity while researchers gathered data on how sensors within his smart knee responded.
The remaining two flights focused on running, with John trying different blade stiffness and knee resistance levels. To simulate “body weight” and to prevent him from floating away from the treadmill in microgravity, the team used a harness and elastic cords, a set-up like the one used on the Space Station.
The results of this project will help establish the optimal configuration of the prosthesis for day-to-day activities on the International Space Station.
Space jogging for health
On Earth, activities like standing and walking place stress on the bones, keeping them strong and dense. In space, the effects of microgravity cause astronauts’ load-bearing bones to weaken much faster.
To combat bone and muscle loss, astronauts use a specialised treadmill, a bike and a weight-lifting machine. When using the treadmill, astronauts wear elastic cords attached to a harness over the shoulders and waist to enable repeated loading of the bones and muscles with each step, helping to keep them strong and healthy for life in orbit and the return to Earth.
Understanding how prosthetic users can participate in these fitness routines is essential for making long-duration space missions feasible for all. Fly! continues to push boundaries and to open up a new chapter in inclusive space exploration.
