On Mars they would encounter extreme temperatures, low air pressure, exposure to harsh ultraviolet light, and generally inadequate soil. We are using genetics to create plants that can give us data we can use to help them survive. Learning to grow plants on Mars will be an important step to human colonization. Bioregenerative life support means that humans, plants and microbes are working together in a renewable system. Humans consume oxygen and produce carbon dioxide.
Plants take carbon dioxide and turn it back into oxygen.
Such life support systems on Mars will probably involve growing crop plants in Martian soil within specially designed greenhouses, said Andrew Schuerger, a manager of Mars projects with Dynamac Corporation at the NASA's Kennedy Space Center. They envision a seed-bearing lander that would scoop up a small portion of Martian soil, add buffers and nutrients, then germinate the seeds to grow within a miniature greenhouse. Thriving plants won't glow at all. They'll look like normal mustard. But plants struggling to survive will emit a soft green light, a signal to researchers that something is amiss.