Regular supply launches keep astronauts aboard the ISS relatively fresh food, but a flight to Mars will not receive any supplies. If we want to visit other planets, we need a refrigerator that won’t disintegrate in space – and Purdue University researchers are working hard to test one.
You may be thinking that nothing is stopping a regular refrigerator from working in space. It sucks out heat and brings in cold air. Easy right? However, refrigerators rely on gravity to distribute oil through the compressor system, which regulates temperature. Hence, these systems do not work or break down quickly in space.
The solution pursued by Purdue team and partner manufacturer Air Squared is an oil-free version of the traditional refrigerator that works regardless of the direction or magnitude of gravity. It was funded by NASA’s SBIR program, which awards promising small businesses and experiments with money to attract them to operational readiness. (The program is currently being awarded for the extended phase II.)
The team spent two years in development and eventually assembled a ready-to-fly prototype. Last month it was finally able to be tested in microgravity, which was simulated in a parabolic flight.
The first results are promising: the refrigerator worked.
“The fact that the cooling circuits were operated continuously in microgravity during the tests with no apparent problems shows that our design is a very good start,” said Leon Brendel, a PhD student on the team. “Our first impression is that microgravity doesn’t change the cycle in ways that we weren’t aware of.”
The short-term weightlessness (the prototype was only weightless for 20 seconds at a time) is of course only a limited test and has already helped fix a problem with the device they are working on. But the next test could be a longer-term installation on board the ISS, whose residents no doubt want a working refrigerator.
While the prospect of cold drinks and frozen (but not freeze-dried) meals is tempting, a regular refrigerator could also be used for all kinds of scientific work. Experiments that require cold environments currently either use complicated small-scale cooling mechanisms or use the near-absolute zero conditions of space. So it’s no wonder that NASA brought them on board the microgravity simulator as part of the Flight Opportunities program.
The analysis of the data collected on the flights is not yet complete, but the success of this first major test confirms both the approximation and the execution of the space refrigerator. Next we need to figure out how it could work in the limited space and continuous microgravity of the ISS.