The European Space Agency’s Melissa project has been working on developing a “half-closed ecosystem” that would eliminate the need to keep re-supplying manned spacecraft, including the International Space Station, by “ indefinitely recycling astronaut waste such as exhaled carbon dioxide and urine and turn it into fresh oxygen and water, as well as how to fit bacteria, algae, plants, chemicals and physical processes together into a self-sustaining circuit,” for the past quarter of a century.
One of the keys to the project has been the development of a photo-bioreactor that uses light to power organisms for turning unwanted carbon dioxide into useable resources by cultivating bacteria and other organisms including Spirulina, a blue-green fresh water algae, which has been harvested for food in Africa,Asia and South America for hundreds of years. In fact one of Cortez’s soldiers wrote about it’s use as food source by the Aztecs and other Mesoamericans. Known by the Aztecs as “tecuitlatl” it was harvested from Lake Texcoco, where it is still being processed today. It has also been traditionally used in cakes, and broth in the African nation of Chad. In fact, the United States National Library of Medicine, reports that “dried Spiulina contains about 60% protein, and “all essential amino acids although with less amounts of methionine, cysteine and lysine than meat, eggs and milk.”
According to the ESA, the Melissa team is preparing to send Spirulina to the Space Station within the next year to test how well it can thrive in a microgravity environment. This will then be followed by an experiment that “imitates astronauts’ breathing, which will be connected to the bioreactor so the Spirulina can grow on a steady stream of carbon dioxide, delivering oxygen in return.”