Space travel can be tricky and astronauts make a lot of sacrifices to travel to space. While some discomfort is expected, what makes space travel troublesome is the fact that even food has to be modified for the zero-gravity environment. For deep-space missions envisaged for future, like a human mission to Mars, storing food is likely to pose a huge problem.
But scientists have found an easy solution to this problem– by developing a technique that converts human waste into food for astronauts.
While that might not sound very appetizing, but it is better than carrying tons of food which in turn will increase the amount of fuel required and hence the total cost of the mission.
So how does this work?
Researchers at Penn State University created an enclosed cylindrical system, four feet long and four inches in diameter, in which select microbes came into contact with the solid and liquid human waste. The microbes broke down the waste using anaerobic digestion, a process in which microbes break down biodegradable waste in the absence of oxygen.
The team found that methane, which was being produced during anaerobic digestion of human waste, could be used to grow a different microbe Methylococcus Capsulatus. This microbe consisted of 52% protein and 36% fats– making it a potential source of nutrition for astronauts.
However, the problem wasn’t entirely solved as the scientists had to figure out a way to get rid of the pathogens.
This was possible only under two circumstances– either an alkaline environment or a high-heat environment. So, the scientists raised the system’s pH to 11, at which a different strain of the bacteria Halomonas desiderata that could thrive. This bacteria had 15% protein and 7% fats. At 158 degrees Fahrenheit, they grew an edible strain of bacteria called Thermus Aquaticus, which consisted of 61% protein and 16% fats– food for astronauts.
During their tests, the team removed 49-59% of solid waste in just 13 hours, which is much faster than existing waste management treatment which takes days.
“We envisioned and tested the concept of simultaneously treating astronauts’ waste with microbes while producing a biomass that is edible either directly or indirectly depending on safety concerns,” said Professor of Geosciences at Penn State Christopher House in a press release.
“It’s a little strange, but the concept would be a little bit like Marmite or Vegemite where you’re eating a smear of ‘microbial goo’,” he added.
At present, astronauts aboard the International Space Station (ISS) recycle a portion of water from urine. However, solid waste management is still an issue. This technique could not only eliminate the problem of solid waste disposal in manned missions but also take us a step closer to deep-space missions.