The MELiSSA (Micro-Ecological Life Support System Alternative) project is (or was, more on that in a bit) a micro-organism- and plants-based ecosystem experiment to help us gain a better understanding of artificial ecosystems, like what would be needed on Mars, and to roadmap the new technology needed for a regenerative life support system for long-term manned space missions, like a lunar base or a mission to Mars - whatever some future president may pick to look "bold", since it is now fashionable to cancel the previous president's plan in order to put the current one's on a new, bold idea.
The core concept of MELiSSA is recovering food, water and oxygen from waste (including feces and urea - don't cringe Muad'Dib, it works), carbon dioxide and minerals. Based on an earthlike aquatic ecosystem, MELiSSA is has five compartmentalized areas - thermophilic anoxygenic bacteria, photohererotrophic bacteria, nitrifying bacteria, photosynthetic bacteria, higher plants, and then the crew.
Waste products and air pollutants that can't be recycled are processed using plants which, in their natural cycle, provide food as well as contributing to water purification and oxygen.
“With the ongoing climate change and increasing environmental problems, these new technologies can also be applicable here on Earth”, said Prof. Benedikt Sas from the Centre of Excellence Food2Know at University of Ghent.
Obviously, knowledge of that sort could also help people to start growing food in areas here which are not currently suitable for food production. We can obviously do it cheaper with GMOs but the food growing is a secondary benefit, since the primary research goal is growing it in a really hostile climate.
Bold stuff, but I haven't seen a real update on MELiSSA in a while and their page hasn't been updated since 2006, but by then they seemed to have validated the mathematical models to a point where a prototype could be developed, so I wrote Project Manager Christophe Lasseur at the European Space Agency for an update and he said it still exists but it was somewhat in limbo; "Yes, the MELiSSA project still exists, but indeed we have to do major efforts for PR issues."
Which basically means finding funding in a competitive budget. We have the same issues in the U.S. - as I have noted in the past, the problem with the James Webb Space Telescope is not that it isn't terrific, but its chronic delays and being wildly over budget starves a lot of worthy smaller experiments that are not 'too big to fail' and so they die.
MELiSSA is a long shot, true basic research, but it has a terrific value for the future of space travel so here is hoping it gets back on track.