Astronauts can run faster on moon surface than previously thought

Scientists have found that astronauts can actually walk faster on the moon than what was previously thought.

Michael Gernhardt, the head of NASA's Extravehicular Activity Physiology, Systems and Performance Project, wanted to learn more about how humans move in low gravity, including the speed at which we break from a walk into a run, to design a modern space suit that permitted freer movement. However, the only way to test the effects of true lunar gravity on our movements while based on earth is to hop aboard NASA's adapted DC-9 aircraft, which reduces the gravity on board by performing swooping parabolic flights, and get running.

To make the discovery, De Witt and colleagues recruited three astronauts and five other registered test subjects that could tolerate the discomfort of the aircraft's bucking flight to test their running. Once the subjects were airborne, the team only had 20s during each roller-coaster cycle,when the gravity on-board fell to one-sixth of that on Earth, when they could test the runner's walking and running styles on a treadmill as the volunteers shifted over a range of speeds from 0.67 to 2m/s.

Back on the ground, De Witt and colleagues analysed the speed at which the walkers gently transitioned into a run. He said that the walk to run transition was expected to occur at 0.8m/s in lunar gravity, based on theoretical calculations. However, when the team calculated the transition speed from their experiments, they were in for a surprise as the average was 1.4m/s.

De Witt suggested that the acceleration forces generated by the counter-swinging arms and legs could account for the interesting shift in transition speed. According to him, even though the atmosphere was lunar gravity, the effective gravity on our system was lunar gravity plus the forces generated by our swinging arms and legs. He explained that the arm-and-leg swinging effect probably happens here on Earth too, but the forces generated by the swinging limbs are negligible relative to our gravity. However, he suspected that they were more significant in weaker lunar gravity, saying, that they contributed more to the gravity keeping you attached to the ground.

The study has been published in The Journal of Experimental Biology.