As humans prepare to return to the moon after an absence of more than half a century, researchers have hit on a radical approach to keeping astronauts fit as they potter around the ball of rock.
To prevent lunar explorers from becoming weak and feeble in the low gravity environment, scientists suggest astronauts go for a run. But, this being space, it’s not just any kind of run – researchers have advised astronauts run several times a day around a “lunar Wall of Death”.
Using a rented Wall of Death – a giant wooden cylinder used by motorcycle stunt performers in their gravity-defying fairground act – a 36m-high telescopic crane, and some bungee cords, researchers showed it was possible for a human to run fast enough in lunar gravity not only to remain on the wall, but to generate sufficient lateral force to combat bone and muscle wasting.
“I’m amazed that nobody had the idea before,” said Alberto Minetti, professor of physiology at the University of Milan. “This could be a convenient way to train on the moon.” And easier than building a spinning moon base that generates the force, like the giant wheel of Space Station One in 2001: A Space Odyssey.
Humans have not set foot on the moon since the end of the Apollo program in 1972, but Nasa and other space agencies are gearing up for a return, with long-term missions in permanent habitats. Nasa’s Artemis astronauts are due to fly around the moon next year with a follow-up mission to the surface as early as 2026.
The hostile lunar environment presents several challenges, from ensuring astronauts have air, food and water to being well protected against space radiation. But without normal gravity to work against, astronauts lose bone and muscle mass, along with the fine nervous system control needed for coordinated movements, making measures to combat “deconditioning” a priority.
Calculations by Minetti and his colleagues show that humans would find it extremely difficult to run around a Wall of Death on Earth without falling down. But in lunar gravity, which is one sixth that on Earth, the feat is much easier. According to his calculations, running at more than 8mph should be enough.
To test the idea, two researchers ran around a 10m-wide Wall of Death while attached to a bungee cord suspended from the crane. The set-up emulated lunar gravity by taking five-sixths off their body weight. Combined with treadmill data, the scientists conclude that running for a couple of minutes at the start and end of each day, should generate enough lateral force, or “artificial gravity” to keep bones and muscles strong and maintain good nervous system control.
Rather than transporting an actual Wall of Death to the moon, astronauts could be housed in circular habitats, allowing them to run around the walls of their off-world homes, the team write in Royal Society Open Science.
“A horizontal running cylinder certainly promises to be a useful countermeasure to help prevent deconditioning in reduced gravity on the moon,” said Maria Stokes, professor of neuromusculoskeletal rehabilitation at the University of Southampton. But specific training for everyday living and work activities would still be needed, she added, to maintain particular skills and ensure astronauts operated safely on the surface.
Nick Caplan, professor of aerospace medicine and rehabilitation at Northumbria University, Newcastle, said the proposal was “certainly novel”, but questioned whether early lunar habitats would be large enough to accommodate such running tracks. With colleagues, he is working on new approaches to exercise in space and on the moon, including inflatable cuffs to compress limbs and restrict blood flow.
“Blood flow restriction exercise has been shown in studies on Earth to give similar muscle, bone and cardiorespiratory training benefits normally seen during higher intensity exercise, at much lower exercise intensities and durations,” Caplan said. “This may, therefore, make existing exercise countermeasures more effective at keeping astronauts healthy without the need for a lunar Wall of Death.”
