If and when the Gateway outpost is deployed in 2023, it will need an airlock to get any useful work done, so ESA is working on a new egress point for scientific experiments for the cislunar manned laboratory. Based on two independent approaches by Airbus and Thales Alenia Space, the final design will be part of the European module ESPRIT, which will also provide telecommunications and spacecraft refueling capabilities.

An airlock seems like a simple enough thing. It's a box with a pair of doors that can't both be opened at the same time while one is under pressure. It allows astronauts and equipment to enter and leave a spacecraft by equalizing pressure in the chamber without having to depressurize or pressurize the entire vehicle.

But designing one isn't that easy. Such airlocks tend to be cramped, full of equipment, and present all sorts of ergonomic problems – especially for weightless astronauts. To overcome this, ESA is currently testing a full-size mock-up of one of the airlocks built by Comex for Airbus in a swimming pool in Marseilles, France.

In a recent series of trials, ESA astronaut Jean-François Clervoy and ESA astronaut trainer Hervé Stevenin checked out the test lock, which was made by using 3D-printed models. The airlock looks more like a futuristic shark cage, but it does include mock-ups of Gateway equipment, including bits of a robotic arm supplied by the Canadian Space Agency. The primary objective of the trials was to test payload operations and to determine where to place the two cameras needed for mission control on Earth to monitor the work inside the lock.

"We wanted to see whether the astronauts had enough space to install hardware onto the payload table, perform any necessary checks and then move them through the airlock tunnel to be exposed to space," says Comex diver Kathrin Nowack. "We also wanted to make sure the crew members had room to carry out maintenance or repair work inside the airlock and to identify where further crew interfaces – such as handrails – are required."

According to ESA, Clervoy and Stevenin were suited for the task because they had weightless experience on the International Space Station and on parabolic airplane flights. For the tests, the astronauts wore neoprene diving suits, but instead of using air bottles, they had regulator hoses to supply air, so they could move more like crew in a weightless shirt sleeve environment. Equally important was learning how to work in such a large lock with heavy payloads.

"While we had seen the dimensions of these components in the documents, seeing full-scale 3D-printed models allowed us to better understand just how incredibly large they are," says ESA study manager Philippe Schoonejans. "It's something we will need to consider throughout the process in terms of balancing mass and strength."

Schoonejans went on to say that the test results will be used to refine the design before it goes to actual fabrication. Meanwhile, both competitors are expected to present their designs and costs for review before ESA's next Ministerial Council in November.

Source: ESA

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