Lunar garden enables hydroponic growing of crops
Researchers at the University of Arizona Controlled Environment Agriculture Center (CEAC) are demonstrating that plants from Earth could be grown hydroponically (without soil) on the moon or Mars, setting the table for astronauts who would find potatoes, peanuts, tomatoes, peppers and other vegetables awaiting their arrival. The technology shows a great potential for application on Earth too.
The research team has built a prototype lunar greenhouse in the CEAC Extreme Climate Lab at UA’s Campus Agricultural Center. It represents the last 5.5 meters (8 feet) of one of several tubular structures that would be part of a proposed lunar base. The tubes would be buried beneath the moon’s surface to protect the plants and astronauts from deadly solar flares, micrometeorites and cosmic rays.
The membrane-covered module can be collapsed to a 1.2-meter (4-foot-wide) disk for interplanetary travel. It contains water-cooled sodium vapor lamps and long envelopes that would be loaded with seeds, ready to sprout hydroponically.
“We can deploy the module and have the water flowing to the lamps in just ten minutes. About 30 days later, you have vegetables”, said Phil Sadler, president of Sadler Machine Co., which designed and built the lunar greenhouse. The UA researchers and Sadler Machine also are collaborating with two Italian firms on this project – Thales Alenia Space (a company that builds hardware for the International Space Station) and Aero Sekur (a company that builds inflatable structures).
Gene Giacomelli, a professor of agricultural and biosystems engineering and a member of the UA’s BIO5 Institute, said that although this robot is built around living green plants (instead of the carbon fiber or steel usually associated with engineering devices) it still requires all the components common to any autonomous robotic system.
These components, which include sensors that gather data, algorithms to analyze that data and a control system to optimize performance, are being designed by assistant professor Roberto Furfaro of systems and industrial engineering, and associate professor Murat Kacira of agricultural and biosystems engineering.
“We want the system to operate itself”, Kacira said. “However, we’re also trying to devise a remote decision-support system that would allow an operator on Earth to intervene. The system can build its own analysis and predictions, but we want to have access to the data and the control system.”
This is similar to the way a CEAC food-production system has been operating at the South Pole for the past six years. The South Pole Growth Chamber, where many ideas which are now used in the lunar greenhouse were developed, was also designed and fabricated by Sadler Machine Co. It provides fresh food to the South Pole research station, which is physically cut off from the outside world for six to eight months each year.
Recycling and efficient use of resources are just as important to the South Pole operation as they will be on the moon. Carbon dioxide is fed into the prototype greenhouse from pressurized tanks, but astronauts could provide CO2 at the lunar base just by breathing. Similarly, water for the plants could be extracted from astronaut urine, and the water-cooled electric lights might be replaced by fiber optic cable (essentially light pipes) which would channel sunlight from the surface to the plants underground.
The lunar greenhouse contains 100 kg (approximately 220 pounds) of wet plant material that can provide 50 liters (53 quarts) of potable water and about 340 grams (0.75 pounds) of oxygen during a 24-hour period, while consuming about 100 kW of electricity and 450 grams (a pound) of carbon dioxide.
The research also could lead to plant colonization in another traditionally hostile environment – large urban centers. One day, we could all use locally grown, fresh food in cities. Aside growing high-quality fresh food, the food would be transported at very short distances, thus reducing the costs and environmental impact of transportation. The technology could also be used to introduce healthy diversity of food which wasn’t grown in the locally available conditions in various parts of Earth, thus enabling agriculture in areas with harsh weather conditions or high altitudes.