The plants can be genetically wired to glow with a soft green aura when they encounter problems. 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 precursor to humans living there. Bioregenerative life support means humans, plants, and microbes working together in a renewable system.
Humans consume oxygen and produce carbon dioxide.
Plants take carbon dioxide and turn it back into breathable air. Such life support systems on Mars will probably involve growing crop plants in Martian soil within specially designed greenhouses, says 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 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.