If you are planning a day at your local park or even a weekend camping trip, you would simply pack all the food, drink, and supplies you need. Similarly, astronauts on short-term space missions can get away with packing the provisions they need to survive in space. But long-term space travel — a round-trip journey to Mars, for example — is no picnic. Depending on the mission, astronauts would need enough food to last for several months or years; a means to clean the air and water; and some efficient way of dealing with waste. Given cost and space limitations, packing supplies on this scale may not be feasible, meaning astronauts need a system that provides a steady source of sustenance while at the same time purifying and recycling waste. The best solution, then, for future deep space explorers: Develop a green thumb.
Earth is a closed, self-sustaining system. We depend on the planet’s regenerative ecosystems to supply all of our biological needs. The central facilitators of these ecosystems are plants. The same qualities that make plant life essential on Earth make it an ideal engine for long-term life support in space. Plants actively purify and recycle air supplies, absorbing carbon dioxide and noxious fumes while releasing oxygen. They also provide a regenerating food supply, transpire water vapor into the air that can be condensed and collected for drinking, and filter contaminants in water through their root systems. For these reasons, NASA has long studied methods for growing and maintaining plants in space as part of a controlled (or closed) ecological life support system (CELSS) for long-term space missions.
Growing plants in space presents unique challenges. For one, soil may not be optimal due to its payload weight, the problem of particles floating about in zero gravity, and the potential for harboring health-threatening, soil-borne pathogens. To address this issue, many NASA projects — including the BioHome, the CELSS Breadboard Project,
Hydroponic techniques — like those used to grow these onions, lettuce, and radishes in this plant growth chamber in Kennedy Space Center’s Space Life Sciences Laboratory — may one day contribute to the development of a bioregenerative life support system.
the Advanced Astroculture Spaceflight Experiments, and the Lunar-Mars Life Support Test Project — have focused on developing and improving hydroponic methods of plant cultivation for use in space. Hydroponics is the practice of growing plants in nutrient solutions, without true soil. This method not only proves more practical for space-based agriculture, but also typically produces larger, healthier plants.