Why The European Space Agency Paid Volunteers Thousands To Lie Flat
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Spending time in space might sound thrilling, but it takes a serious toll on the human body. Weightlessness affects everything from muscles to blood flow. Hence, before astronauts head to the Moon or Mars, scientists must find ways to reduce the physical effects of long-term space travel.
To help them, ten healthy male volunteers signed up for an unusual challenge. They agreed to spend ten days lying flat in a lab in France. For their time, each participant earned $5,500. To qualify, they had to be between 20 and 40 years old, stand 5.4 to 5.9 feet tall 1.65 m to 1.8 m) and have no allergies or food restrictions.
The experiment, run by the European Space Agency (ESA), began on March 13, 2025. The volunteers lay in bathtub-like containers covered with waterproof fabric for ten days. This kept them dry while they floated in water. Their bodies were submerged up to the chest, with their arms and heads above the surface. These makeshift waterbeds were designed to mimic the weightlessness experienced in space.
Meals were eaten flat on their backs, with trays balanced on floating boards and pillows tucked behind for support. Even bathroom trips were an adventure. The volunteers had to stay reclined while being rolled away on a trolley!
This method, called dry immersion, offers a cheaper and simpler way to study how the body reacts to the absence of gravity. It produces many of the same effects, including blood rushing to the head, fluid shifts, and bone and muscle loss.
After the ten-day immersion, the volunteers stayed at the lab for another five days for medical tests and recovery routines. This allowed the researchers to monitor how their bodies adjusted to normal conditions. Ten days after leaving the facility, the men returned for a final checkup to ensure there were no lingering effects from the experiment.
ESA scientists believe the data from this study — and others like it — will be key to getting astronauts ready for deep-space travel. However, the benefits of this research could also be of use to help people on Earth. Studying how the body responds to long periods of inactivity might lead to better treatments for bedridden patients, the elderly, and those with mobility issues.
"Bridging the gap between spaceflight and ground-based research is essential for human space exploration," said Marc-Antoine Custaud, who led the study. "Our findings have significant implications for Earth-based medicine, particularly in age-related conditions."
Resources: dailygalaxy.com, ESA.int
