Running around a 'wall of death' could keep moon settlers fit

Future moon settlers could exercise by running around the inside of a circular wall – and just a few laps a day could counteract some of the negative effects of low lunar gravity.

The moon’s gravitational pull is about one-sixth as strong as that of Earth. This means lunar astronauts’ bodies support much less weight, and an extended stay would cause their muscles to atrophy and their bones to get less dense. Microgravity conditions also affect the way blood flows around the body, harming the cardiovascular system.

Taking inspiration from the “wall of death” stunt performed by motorcycle riders, Alberto Minetti at the University of Milan in Italy and his colleagues have come up with a novel way for lunar settlers to combat these ill effects.

High-speed motorcycles can travel along a circular wall without slipping thanks to a combination of friction and centripetal force. People can’t run quickly enough to do that on Earth, says Minetti. “But we wanted to see if it was feasible for us to do it on the moon.”

The team members hired an amusement park wall of death that was roughly 9.7 metres in diameter and 5 metres high. They separately attached two volunteers by a bungee cord to a pole high above the wall to support their weight, which made them functionally 83 per cent lighter – equivalent to their weight on the moon.

Both runners were able to complete a few laps around the wall at speeds of around 6 metres per second.

The force experienced by the volunteers while in contact with the wall was similar in magnitude to gravity on Earth. “What we recreated by running horizontally on the vertical wall is a sort of artificial gravity,” says Minetti.

On the moon, that would be enough force to counter the main issues of low gravity, such as bone density loss and cardiovascular fitness, he says. “Running twice a day, for a few minutes at a time, should be enough.”

The exercise could also be used to help astronauts prepare for their return to Earth, he says.

“From the perspective of experimental design and scientific analysis, this study looks robust, important and relevant,” says Ilan Kelman at University College London. “Especially considering the limited space in any lunar settlement, this experiment is a helpful and needed contribution to understanding time and cost-efficient ways of keeping moon settlers healthy.”