Space travel, especially to the most distant planets, requires self-sufficiency in oxygen, water, and food. No external sources can be imported into these shuttles en route! Therefore, microalgae, so small, so powerful, and so nutritious, are currently the subject of serious scientific studies with the aim of accompanying future astronauts on their journeys.
SPACE ADVENTURE, TECHNICAL CONSTRAINTS
For flights lasting a few days, it is easy to plan the necessary supplies for the occupants of spacecraft while maintaining sufficient storage space for waste. But, for journeys lasting several months, far away and therefore without refueling, such as going to Mars, this logistical aspect becomes a real constraint, especially in terms of weight . Indeed, a human organism uses at least 5 kg of water, food and oxygen per day and produces numerous gaseous, liquid and solid wastes. Since the tonnage to be transported is proportional to the duration of the journey, two solutions then become available: increase the power of the launchers in order to send the tonnage necessary for life over several months or provide highly concentrated nutritional resources and set up an autonomous system for recycling the waste produced by these space travelers.
THE MELISSA PROJECT, A CLOSED AND ECONOMICAL ECOSYSTEM
The European Space Agency, through the Melissa 1 (Micro-Ecological Life Support Alternative) project, has been aiming for this last solution by studying for more than 25 years the possibility of providing a closed and self-sufficient ecosystem within spaceships.
Spirulina seems to be particularly suitable for this type of mission. Indeed, micro algae have a double interest, they have the capacity to transform fatty acids and carbon dioxide (CO2) into oxygen (O2) and are particularly interesting as quality nutritional supplements . However, many constraints, non-existent on Earth, are present in space. The absence of natural reserves (oceans, soil, atmosphere) and the presence of radiation cause a rapid evolution of microorganisms. These autonomous systems are responsible for keeping astronauts alive and therefore need to be perfectly operational when they are implemented. Currently, tests on Earth as well as in space are being carried out to find the right balance and guarantee their effectiveness.
FEEDING ASTRONAUTS, A “MICRO”-SIZED CHALLENGE
In order to be taken on board, food must meet several criteria, including not being crumbly, being pasteurized to avoid contamination on board, and being tasty because the sense of taste is diminished in weightlessness. But they are also asked to be compact, light, and nutritious . However, these last three criteria are difficult to meet for common foods. Indeed, for a large majority of them, the nutritional intake is sufficient for a relatively large quantity and therefore rather space-consuming. So why not supplement the rations with spirulina, compact, light, and very nutritious?
For comparison, for an intake of around 25g of high biological value protein , you need to consume 100g of meat compared to only 35g of spirulina. And since on average a 70kg astronaut should consume around 220g of meat, by dividing the ration by 2 and supplementing with spirulina, you would already gain more than 2kg of weight for 1 month . This may not seem like much, but when every gram is counted, it can quickly add up. When we also know that spirulina is rich in vitamins and minerals, there is no doubt that microalgae will have their place in the next space odysseys.
And if one day man really walks on Mars, it will undoubtedly be thanks to micro-algae!
Sources
https://www.esa.int/Our_Activities/Space_Engineering_Technology/Melissa
