MELiSSA, a circular ecosystem to go to Mars!

Posted on 07 November 2017.

The European Space Agency is working on the design of a circular ecosystem to recycle waste in space to produce the food needed for long space travel.

A complete artificial ecosystem that replicates Earth's natural life cycles on a small scale and at an accelerated rate.

Exploring Mars is a favorite subject in science fiction and this dream has fueled human imagination since Neil Armstrong set foot on the Moon in 1969. It could well become a reality in the coming years. European Space Agency (ESA) researchers are working on the design of a circular economy loop to recreate the conditions of the biosphere in a space ship to feed astronauts during long space travel.

30 tons for six people: mission impossible

To survive in space, a person needs about 1 kg of food, 1 kg of oxygen, and 3 kg of water every day. Given that a return trip to Mars takes three years, 30 tons of resources would be needed on-board for an average crew of six people. Mission impossible from a technical point of view as space ships are too small and the reactors are not powerful enough to lift off such a load. The only solution is to recycle waste into resources during the journey.
Created in 1989 by the ESA, the project MELiSSA aims precisely to develop a closed circuit that recycles everything that astronauts discharge (meal left overs, urine, excrement) to produce what they need to live (water, food, and oxygen). This is a complete artificial ecosystem that replicates Earth's natural life cycles on a small scale at an accelerated rate.

A miniature biosphere in Barcelona

The MELiSSA ecosystem was inaugurated in 2009 at the Autonomous University of Barcelona (UAB). Forty rats, which consume the same amount of oxygen as one human, were put in it. Their organic waste was recycled and liquefied by bacteria transforming it into substances that can be reused: CO2, nitrate, and mineral salts. Each of these substances is used as fertilizer to grow plants in artificial greenhouses.
Plants are carefully chosen for their properties, like spirulina, which has the advantage of being a super-food, rich in vitamins, which also produces a lot of oxygen. Plants effectively release oxygen through the photosynthesis process as they grow as well as water vapor. Therefore, the greenhouse's resources provided the rats with food, oxygen, and drinking water.

Circular economy knowledge transfer

Now, it needs to be proved that the ecosystem can work over a long period of time and, above all, without microbial contamination. MELiSSA must be able to recycle 100% of CO2 discharged and produce 100% of the oxygen required as well as 20% of the food needed by a human. It will take another fifty years to ensure that the MELiSSA technology is viable and send it into space.
It is one of the most advanced short circular economy circuits. The research and innovations carried out at the UAB thus make it possible to transfer knowledge from space to the Earth. For example, some wastewater treatment plants now use nitrification processes developed by MELiSSA. This is called "killing two birds with one stone": the circular economy will help us go explore another planet while taking better care of our own.