The MELISSA Pilot Plant laboratory provides the site where the different advances around the Micro Ecological Life Support System Alternative project coordinated and fostered by the European Space Agency, as well as other associated technologies, are integrated and demonstrated. During its first period of operation, the definition of the different compartments at an individual basis has been achieved, and the complete facility is being re- designed to face a new period of integration of all these compartments. The final objective is to demonstrate the potentiality of MELISSA as life support system, and to use this facility as a test bed to study the robustness and stability of the continuous operation of a complex biological systems. This includes the testing the associated instrumentation and control for a safe operation, characterization of the chemical and microbial safety of the loop, as well as tracking the genetic stability of the microbial strains used. This new period is envisaged as a contribution to the further development of more complete biological life support systems for long term manned missions, that should be better defined from the knowledge to be gained from this integration phase. The presentation will summarize the present status of the Pilot Plant and the planned steps for the new period.