The European Space Agency (ESA) is developing technologies that it hopes one day could result in a machine to convert human feces and urine, and exhaled carbon dioxide, into usable substances — food, water and oxygen — required to sustain life in space.

ESA inaugurated a pilot plant in Barcelona, Spain, to pursue the technology.

That event came just after the United States agency, NASA, announced that a more limited system installed aboard the International Space Station is working successfully to convert urine, sweat and exhaled vapor into pure drinking water.

ESA said its unit, which also recycles feces and exhaled air, once developed would be useful for humans living on the moon or Mars.

MELiSSA, short for Micro-Ecological Life Support System Alternative, is an artificial ecosystem to recover food, water and oxygen from waste (faeces and urine), carbon dioxide and minerals. The laboratory will help in the development of technology for a future regenerative life support system for long-duration human space exploration missions, for example to a lunar base or to Mars.

A trip to Mars could take years, including six months or more living on the Martian surface.

The second generation MELiSSA pilot plant is located within the School of Engineering at the University Autonoma of Barcelona (UAB), Spain. The MELiSSA project is partially funded by ESA through the Directorate of Human Spaceflight and the Directorate of Technical and Quality Management.

The pilot plant at UAB demonstrates the associated technologies with a "crew" of 40 rats – together their oxygen consumption is equivalent to one person. This demonstration will last for more than two years, a length of time considered representative of human space exploration missions. The rats will be kept under close veterinary supervision throughout.

MELiSSA goes further than other recycling systems used on Mir or the International Space Station that purify water and recycle urine and exhaled carbon dioxide, but do not attempt to recycle organic waste for food production.

Based on the principle of an aquatic ecosystem, the ESA facility consists of five interconnected compartments. In three of them, waste is progressively broken down by fermentation processes. In the fourth compartment, algae or plants are grown to produce food, oxygen and water. The fifth compartment is where the crew lives — rats in the case of this experiment, and on real missions, astronauts.

The first generation MELiSSA pilot plant, which began operating in November 1995, was gradually assembled together with components developed all over Europe. The preliminary achievements of the first pilot plant lead to the decision in 2005 to develop an improved facility.

The second generation MELiSSA pilot plant was built in 2006-2007 and will progressively incorporate newly designed compartments. The compartments will first be independently tested, characterised and optimised during the next 18 to 24 months. They will then be gradually interconnected in order to start a full-scale demonstration of MELiSSA in 2014.