The 2020 edition of MELiSSA Conference is the European platform dedicated to closed life support system. It is the place to share and exchange about fundamental and applied research for Space and Earth applications. All the respective communities: air, water, waste recycling, food production and preparation, modelling, control, safety, circular systems, education and societal impact,... are represented. The Conference will highlight and foster the collaboration between researchers, engineers, experts, private and public organisations.