Following a new National Aeronautics & Space Administration's (NASA) bill that Congress passed in March authorizing $19.5 billion spending for space exploration in 2017, manned missions to Mars are closer to reality than ever before.
As both public and private enterprises gear up for a return to the moon and the first human footsteps on the red planet, there is a renewed focus on keeping people alive and productive in these extreme environments.
Plants, and specifically crop plants, will be a major component of proposed regenerative life-support systems as they provide food, oxygen, scrub carbon dioxide and aid in water recycling — all in a self-regenerating or "bioregenerative" fashion. Without a doubt, plants are a requirement for any sufficiently long-duration (time- and distance-wise) human space exploration mission.
There has been a great deal of research in this area — research that has not only advanced agriculture in space but has resulted in a great many Earth-based advances as well (e.g., LED lighting for greenhouse and vertical farm applications, new seed potato propagation techniques, etc.).
A recent article by Dr. Raymond M. Wheeler from NASA's Kennedy Space Center, now available open access in the journal Open Agriculture, provides an informative and comprehensive account of the various international historical and current contributions to bioregenerative life support and the use of controlled-environment agriculture for human space exploration.
Covering most of the major developments of international teams, it relates some of this work to technology transfer, which proves valuable here on Earth.
The idea of using plants to keep people alive and productive in space is not new in concept or in scientific inquiry. The article covers a large portion of the historical international research effort that will be the foundation for many of the trade studies and mission design plans for use of artificial ecosystems in space.
Research in the area started in 1950s and 1960s through the works of Jack Myers et al., who studied algae for oxygen production and carbon dioxide removal for the U.S. Air Force and NASA. Studies on algal production and controlled-environment agriculture were also carried out by Russian researchers in Krasnoyarsk, Siberia, beginning in the 1960s, including tests with human crews whose air, water and much of their food were provided by wheat and other crops.
NASA initiated its Controlled Ecological Life Support System (CELSS) Program in the early 1980s, with testing focused on controlled-environment production of wheat, soybean, potato, lettuce and sweet potato. Findings from these studies paved the way to conduct tests in a 20 sq. m, atmospherically closed chamber located at Kennedy Space Center.
At about the same time, researchers in Japan developed a Closed Ecology Experiment Facilities (CEEF) in Aomori Prefecture to conduct closed-system studies with plants, humans, animals and waste recycling systems. CEEF had 150 sq. m of plant growth area that provided a near-complete diet, along with air and water regeneration for two humans and two goats.
The European Space Agency MELiSSA Project began in the late 1980s and pursued ecological approaches for providing gas, water and materials recycling for space life support and later expanded to include plant testing.
A research team at the University of Guelph in Ontario started a research facility for space crop research in 1994. Only a few years later, they went on to develop sophisticated canopy-scale hypobaric plant production chambers for testing crops for space and have since expanded their testing for a wide range of controlled-environment agriculture topics.
Most recently, a group at Beihang University in Beijing, China, designed, built and tested a closed life support facility (Lunar Palace 1), which included a 69 sq. m agricultural module for air, water and food production for three humans.
As a result of these international studies in space agriculture, novel technologies and findings have been produced; this includes the first use of light emitting diodes (LEDs) for growing crops, one of the first demonstrations of vertical agriculture, use of hydroponic approaches for subterranean crops like potato and sweet potato, crop yields that surpassed reported record field yields, the ability to quantify volatile organic compound production (e.g., ethylene) from whole crop stands, innovative approaches for controlling water delivery, approaches for processing and recycling wastes back to crop production systems and more.
The theme of agriculture in space has contributed to and benefited from terrestrial, controlled-environment agriculture and will continue to do so into the future. There are still numerous technical challenges, but plants and associated biological systems can and will be a major component of the systems that keep humans alive on the moon, Mars and beyond.
The original review article appeared within the special issue dedicated to agriculture in space and is available for free to read, download and share in on De Gruyter Online.