Food For Astronauts

The greenhouse is currently being used by NASA and the DLR for a joint series of experiments on vegetable cultivation techniques on the Moon and Mars. NASA scientist Jess Bunchek is trialling how future astronauts could grow lettuce, cucumbers, tomatoes, peppers and herbs, using as little time and energy as possible, and she attends to her crop on a daily basis, putting greenhouse technologies and plant varieties to the test .

“We’re gaining a significant amount of hands-on knowledge about operational aspects such as crew demands and workload,” says Vrakking. “The procedures involved with every activity within the greenhouse need to be investigated and optimised before a greenhouse eventually begins operation on the Moon or Mars, to free up astronauts to focus on exploration and science.”

Although it may seem counter-intuitive in an environment that can reach -50°C, cooling is essential for the greenhouse to function, as lighting and other electrical equipment creates heat that needs to be removed. “The cooling system is very important,” says Vrakking. “And we need to have accurate control over the amount of heat that is removed from the facility, to maintain the optimum air temperature and humidity levels.”

Jan Levin, former Branch Manager of wholesalers Frigotechnik in Bremen, remembers he found it hard to believe that a customer wanted a cooling system that would work in such demanding conditions. “When they first contacted me, they said they wanted to meet in person and explain the project,” he remembers. “We went for a coffee and when they started talking about simulating weather conditions on the Moon, at first I thought they were joking.”

Levin contacted Güntner and then worked closely with the company’s technical team to find a cooling solution that would do the job. The answer was an adapted version of a Güntner Flat COMPACT Dry Cooler. It was a considerable technical challenge.

“You have to have special lubrication for the bearings on the fans and motors,” says Udo Brünjes, at that time Sales Manager at Güntner. “And that means oil or grease with high viscosity at very low temperatures, otherwise there’s a risk that the fan bearings will break. At the same time you have to make sure the oil doesn’t become too liquid at higher temperatures, meaning it doesn’t adhere to the bearings and the fans will jam. We also needed low temperature protection for the cables and a heating system for the box containing the electronics, to avoid freezing.”