The regular supply launch supplies astronauts with relatively fresh food on the ISS, but a flight to Mars will not receive delivery. If we’re going to travel to other planets, we’ll need a fridge that doesn’t break into space – and researchers at Purdue University are hard at work testing.
You might think that there is nothing to prevent a regular refrigerator from working in the space. It expels heat and cool air. Simple, isn’t it? But refrigerators rely on gravity to deliver oil through compressor systems that control temperature, so these systems in space do not work or break down quickly.
The solution being adopted by the Purdue team and partner manufacturer Air Square is an oil-free version of the traditional fridge that will work regardless of the direction or magnitude of gravity. It was funded by NASA’s SBIR program, which provides funding to promising small businesses and experiments to drive them toward mission readiness. (The program is currently on its Phase II extended-term awards.)
In two years of development, the team finally assembled a flight-ready prototype, and was able to test it in simulated microgravity in a parabolic aircraft flight late last month.
Initial results are promising: the fridge worked.
“The fact that the refrigeration cycle operates in continuous microgravity during tests without any apparent problems shows that our design is a very good start,” Leon Brendel, a Ph.D. he said. Students in the team. “Our first assumption is that microgravity does not change the cycle in ways we were not aware of.”
The short-term microgravity (the prototype was weightless for only 20 seconds at a time) is certainly only a limited test, and it helps to overcome a problem with the device they are working on already. But the next test could be a long-term installation on the ISS, whose residents would undoubtedly prefer a working fridge.
While the possibility of cold drinks and frozen (but not freeze-dry) food is tantalizing, a common refrigerator can also be used for all types of scientific work. Experiments that require cold environments currently use either complex, small-scale cooling mechanisms or near-absolute-zero conditions of space. So it is no surprise that NASA rode them on the microgravity simulator as part of the flight opportunity program.
The data collected on the flights continues to be analyzed, but the success of this first large test validates both the approach and execution of the space fridge. The next is exploring how it can work in the confined space and continuous microgravity of the ISS.