An international team of scientists have developed a “space salad” that can keep astronauts well-nourished on future missions into deep space.
The salad consists of seven ingredients — soybeans, poppy seeds, barley, kale, peanuts, sunflower seeds, and sweet potatoes, all in carefully measured amounts — that can be grown in small enclosures on a spacecraft and fulfill the nutritional needs of astronauts on long-duration trips.
Researchers from Australia, the U.K., and the U.S. chose the ingredients based on their nutritional value, growth rate, water and space requirements, and the amount of inedible waste produced.
“Mars exploration will be only possible with fresh grown plants [because] food payload for two to three years isn’t possible,” Shu Liang, a doctoral student at the University of Adelaide who led the new research, tells Astronomy.
While the ingredients selected for this space salad are the best options available at this time, the team is now working on selectively breeding them to increase their nutritional value, decrease their required growing space, and increase their ability to quickly grow using hydroponic fertilizers.
Anything that can’t be eaten — such as the leaves and stalks of the peanuts and sweet potatoes — will be burned, says Liang. And any nutrients extracted from the resulting waste will then be recycled into the hydroponic system, she adds.
Nutrition in space
Astronauts don’t follow the normal circadian rhythm that most of us follow here on Earth, which consists of about eight hours of sleep followed by 16 hours of being awake, says Liang. Social activities, exercise, and sports here on Earth are also timed to fit that pattern, which means astronauts in space must cope with any differences.
The human body also experiences physiological stresses in space, where it’s exposed to unusual conditions like microgravity and increased cosmic radiation for relatively long periods of time. Microgravity, for example, causes bone loss, which means that astronauts require more than the usual amount of nutrients like calcium and vitamin D.
“The nutritional requirements in space are different than on Earth,” says Liang. That means astronauts on long-duration trips will need to consume nutrient-dense foods to offset some of the detrimental health effects spaceflight has on the body, she adds.
Crops for spacecraft
To determine the best ingredients for the space salad, Liang and her colleagues began with a selection of 100 crops. They then measured each crop’s carbohydrates, component fats, vitamins, amino acids, fiber content, and other nutrients.
