Space travel, especially to the most distant planets, requires self-sufficiency in oxygen, water and food. Nothing can be brought on board these spacecraft along the way! That is why microalgae – so small, so powerful and so nutritious – are currently the subject of serious scientific research aimed at supporting future astronauts on their voyages.
Read also: Understanding algae as well as possible
SPACE EXPLORATION: THE TECHNICAL CONSTRAINTS
For flights lasting a few days, it is easy to plan the supplies needed by the crew while keeping enough storage space for waste. But for long-distance journeys lasting several months with no possibility of resupply, such as a trip to Mars, logistics become a real constraint, especially in terms of weight. The human body uses at least 5 kg of water, food and oxygen a day and produces a great deal of gaseous, liquid and solid waste. Since the tonnage to be carried is proportional to the length of the journey, there are two options: increase the power of launchers so they can carry the tonnage needed to sustain life for several months, or plan for highly concentrated nutritional resources and set up an autonomous system for recycling the waste produced by these space travellers.
Read also: Algae and their many uses
THE MELISSA PROJECT: A CLOSED, RESOURCE-EFFICIENT ECOSYSTEM
With its MELiSSA project1 (Micro-Ecological Life Support System Alternative), the European Space Agency is pursuing the second option, and has spent more than 25 years studying the possibility of building a closed, self-sufficient ecosystem inside spacecraft themselves.
Spirulina seems particularly well suited to this type of mission. Microalgae offer a twofold benefit: they are able to convert fatty acids and carbon dioxide (CO2) into oxygen (O2), and they are particularly valuable as high-quality nutritional supplements. However, space presents many constraints that do not exist on Earth. The absence of natural reserves (oceans, soil, atmosphere) and the presence of radiation cause microorganisms to evolve rapidly. These autonomous systems are what keep astronauts alive, so they must be fully operational when put into use. Tests are currently being carried out both on Earth and in space to find the right balance and ensure they work effectively.
FEEDING ASTRONAUTS: A “MICRO”-SIZED CHALLENGE
To be taken on board, food must meet several criteria: it must not produce crumbs, it must be pasteurised to avoid contamination on board, and it must be tasty, because the sense of taste is dulled in zero gravity. But it must also be compact, light and nutritious – and these last three criteria are hard to combine in everyday foods. Most of them only provide sufficient nutrition in relatively large quantities, which take up a lot of space. So why not supplement rations with spirulina, which is compact, light and highly nutritious?
Read also: Algae and the vegan diet
By way of comparison, to obtain around 25 g of high-biological-value protein, you need to eat 100 g of meat but only 35 g of spirulina. And since a 70 kg astronaut would need to eat around 220 g of meat a day on average, halving that ration and making up the difference with spirulina would already save more than 2 kg in weight over 1 month. That may not sound like much, but when every gram counts, it can quickly tip the scales. Add to this the fact that spirulina is rich in vitamins and minerals, and there is no doubt that microalgae will have their place in future space odysseys.
And if humans ever really do walk on Mars, it will no doubt be thanks to microalgae!
Read also: Algae and the environment
Sources
https://www.esa.int/Our_Activities/Space_Engineering_Technology/Melissa
