Particularly, where would we find sources of food when we are migrating from Earth to an exoplanet, a trip which would essentially take thousands of years to make? We can take inspiration from movies like Passengers and The Martian, specifically the latter where Matt Damon's character grew food. The idea is simply to grow a farm inside the spaceship that would sustain all the basic needs of the crew.
But how much space would you need aboard a spaceship in order to build a farm? Frederic Marin, an astronomer at the Astronomical Observatory of Strasbourg in France, along with his colleagues tried to calculate that and this is what they found:
For a crew of 500 people with omnivorous diets, just 0.45 square kilometres would be enough to feed them all. This assumes that fruits, vegetables, starch, sugar, and oil would be produced using aeroponic techniques, which allow plants to grow without soil, while conventional farming would produce meat, fish, dairy, and honey.
(Image credit: NASA/JPL)