European Space Agency astronaut reserve John McFall tested his prosthetic hardware in microgravity by squatting, walking and running on a treadmill. The team tested the performance of the prosthetic hardware in repeated periods of microgravity during over 90 parabolas across 3 flights.  

The performance of a lower limb prostheses has been tested in microgravity conditions for the first time during the latest ESA parabolic flight campaign on the ‘Zero G’ aircraft.  

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. 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 that have historically prevented a lower limb amputee taking part in a long-duration mission to the International Space Station.   

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 Fly! research team designed the Ampu-T2 experiment to find out exactly how the mechatronic knee behaves in microgravity, and to determine the optimum setup of the running prosthesis for running on a treadmill in space.   

John tried different blade stiffnesses 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 set up of the running prosthesis for use in space and determine the most suitable programming and configuration of the mechatronic knee for day-to-day activities living on the Space Station.