As a test of a new system designed to transport incapacitated astronauts on the lunar surface, ESA and NASA astronauts have conducted a simulated rescue of an "injured" moonwalker on the seafloor. Part of NASA's 22nd Extreme Environment Mission Operations (NEEMO-22) mission, the exercise used the buoyancy and terrain of the underwater environment as a way of simulating lunar gravity and conditions.

With several nations and private companies exploring a return to the Moon, a problem that first cropped up during the Apollo missions has reemerged: what happens if an astronaut is injured while away from the lander or base? True, the Moon has only one sixth the gravity of Earth, but an Apollo astronaut and his spacesuit weighed in at about 485 lb (220 kg), which translates to 80 lb (37 kg) in lunar gravity. That might be more manageable, but is still way too much for another suited astronaut to try to lift or drag too far.

To make rescue work easier, ESA is developing its Lunar Evacuation System Assembly (LESA). Built by Dutch company HAL-3 Projects at the space agency's astronaut center in Cologne, Germany, it took only six months to go from concept to test stage. It involves a foldable pyramid-shaped frame on wheels that can lift an astronaut and deposit them on a wheeled stretcher that can be pulled along in low gravity.

So far, LESA has been tested in a swimming pool, but it was later taken to the Aquarius underwater habitat, located 3.5 mi (5.6 km) off Key Largo in the Florida Keys Marine Sanctuary in the Atlantic Ocean at a depth of 62 ft (19 m). Aquarius is the base for the NEEMO missions that, since 2001, has allowed 22 teams of international astronauts to spend a fortnight carrying out experiments as well as practicing with new techniques and technologies in the simulated weightlessness of the undersea environment.

In this case, ESA astronaut Pedro Duque and NASA astronaut Kjell Lindgren took turns outside the habitat playing casualty and rescuer as they put the LESA through its paces with the sandy, uneven seabed standing in for the lunar surface. Their suits' buoyancy was also adjusted to simulate lunar and then Martian gravity. The feedback from the trials will be used to improve the system.

"We designed it with international cooperation in mind and based on our expertise in spacewalks and experience working with NASA on the preparation of future space exploration," says ESA astronaut trainer and NEEMO-22 member Hervé Stevenin. "This lunar simulation capability will allow more tests of innovative European hardware for future human exploration of the Moon."

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