Much as we admire Mark Watney’s ingenuity in manufacturing water from leftover rocket fuel to grow survival potatoes in his Martian garden, we do also realise that fact is much harsher than fiction. In the 2015 movie Martian, food could be grown on the Red Planet on the director’s (Ridley Scott) whim, but really nothing can grow easily once you leave the earth’s benign atmosphere.

That’s why the US space agency, NASA, put out a Space Food Challenge; and the phase-2 winning entries were announced last week.

Among the eight who graduated to the third phase of the competition is the Brooklyn, New York-based Air Company, whose idea is to make alcohol from an astronaut’s breath. The alcohol is food for a yeast variety that can produce something edible.

Massachusetts Technology Review quotes Air Company’s co-founder and CTO Stafford Sheehan as saying that the system would ferment continuously to supply food, so that “whenever you feel like you want a space protein shake, you make one from this yeast that’s growing”.

Another successful entrant, Interstellar Lab, based in Florida, makes ‘bio pods’ or capsules that have their own temperature and humidity control and watering system. You can grow a variety of plants, and even insects such as black soldier flies, for proteins.

NASA needs to figure out how to grow food in outer space because it is impossible to carry enough food for astronauts on long missions, such as a Mars voyage, which would take a year each way.