For decades, space medicine scientists have been studying the effects of weightlessness on the human body and how to correct them. But what about low gravity, like that on the Moon? In anticipation of astronauts returning to the lunar surface , ESA's education coordinator David Green and science operations engineer Tobias Weber are leading a study at the space agency's astronaut center in Cologne to learn more about the long-term effects of lunar gravity.
Thanks to a series of space station experiments dating back to the 1970s and earthbound bed rest studies, scientists have developed a growing understanding of how zero gravity affects the human body as well as learning how astronauts can most effectively live and work in free fall.
Over the past fifty years, we've seen how a lack of gravity can cause bone loss, weaken muscles, cause cardiopulmonary problems, and adversely affect sinuses, taste, eyesight, the brain, and even the immune system. Some of these effects as as trivial as an astronaut's face swelling up, while others are so basic to cellular function that they raise doubts about how long people can remain in space without artificial gravity.
However, when it comes to low gravity, we are still very much in the dark. True, NASA did carry out extensive studies during the run up to the Apollo missions and the American space agency does possess its Active Response Gravity Offload System (ARGOS) at the Johnson Space Center in Houston, Texas, which simulates zero and low gravity, but these have been largely about how to move and work in space or on the Moon.
But what about medical effects of living in one-sixth Earth gravity for long periods of time?
To find out, ESA and the German Aerospace Center (DLR) began its "Movement in low gravity study" in 2017. This uses a vertical treadmill with the subject suspended horizontally on a web of wires that take up five-sixths of a person's weight. In this way, the team could study how activities like hopping and jumping in lunar gravity affects the Achilles tendon and helps to offset bone and muscle loss.
"We believe jumping and hopping on the Moon may provide forces similar to walking and running on Earth. This would allow astronauts to maintain their bone and muscle condition through everyday movement," says Tobias. "This may reduce the need for training equipment such as on the Space Station and it is something we hope to explore further."
So far, ESA says that the results have been promising, but the current rig doesn't allow subjects to make the spectacular jumps that are possible on the Moon, so the next step will be to move the study to Houston, where the ARGOS system will allow a greater range of movement and a better understanding of the forces encountered by the bones, muscles and tendons in low gravity.
The hope is to eventually build a similar system in Europe, called Luna 2, to help train ESA astronauts for future manned lunar landings.
The NASA video below shows ARGOS in action.
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