Fly! study areas
Fly! is improving our understanding of the barriers spaceflight presents for astronauts with a physical disability. Key areas include adapting to microgravity, maintaining physical fitness and rehabilitation, and integrating assistive technologies and tools to support astronauts throughout the mission.
Here are a few examples of the assessments carried out as part of the Fly! initiative.
The fluid shift study
In microgravity, body fluids shift headward, causing a 5-10% reduction in the volume of the lower legs of astronauts within the first few hours in space. This reduction in size and shape of the calf and thigh persists throughout the whole mission.
During the Fly! Feasibility Study, tilt-table and head-down tilt cycling tests were conducted to evaluate whether these fluid shifts impact the volume of the residual limb (i.e., stump), or the fit and comfort of a prosthesis for an astronaut with a lower limb amputation. The fluid shift study took place at :envihab, a building with specialised laboratories for studying the effects of extreme environmental conditions on humans.
Parabolic flight campaigns
When living and working on the International Space Station, astronauts translate (i.e., float from place to place) by pushing off from surfaces. To secure themselves in place when performing tasks, such as working with tools or even practising first aid, astronauts use straps or handrails to stabilise their feet or lower body.
The Fly! Feasibility Study evaluated during parabolic flights the ability of an astronaut with a lower limb amputation to translate and stabilise himself, perform Cardiopulmonary Resuscitation (CPR), and optimise prosthetic hardware to ensure it performs well across all mission phases.
Parabolic flights offer brief periods of weightlessness. Researchers leverage these flights for short-duration, hands-on scientific and technological investigations, including astronaut training and pre-flight validation of instruments for the International Space Station.
Running on the Altered G Treadmill
On Earth, stress placed on the bones in the lower back, hips, and legs under the force of gravity helps maintain their density and strength. Microgravity removes this stress, resulting in a reduced strength of the load bearing bones at a much faster rate compared to normal ageing on Earth. To counteract this, astronauts run on a special treadmill at a fraction of their bodyweight.
Amputees run using a prosthetic ‘blade’ with a particular stiffness designed to provide an appropriate level of support during each stride. The Altered G Treadmill, typically used for lower limb injury rehabilitation, allows for people to run on Earth at a fraction of their bodyweight, in a similar way of how astronauts run on the Space Station.
The Fly! Feasibility Study used the Alter G Treadmill to determine the ideal running blade stiffness for training on the treadmill on the International Space Station. Higher fidelity tests are planned on a future parabolic flight campaign to optimise the stiffness and range of movement of the prosthetic knee joint to ensure a comfortable run in microgravity.