At the International Astronautical Congress IAC on 27th September 2016, Elon Musk, CEO, lead designer, and founder of SpaceX, presented a detailed concept for a superheavy lift two-stage rocket, called Interplanetary Transport System (ITS). This system is expected to be capable to transport up-to one hundred passengers to Mars. Since space is a hazardous environment, humans can only survive in it with special equipment. This equipment is normally called Environmental Control and Life Support System (ECLSS), which must ensure suitable environmental conditions and a continuous consumable supply for the crew. For the anticipated system, the development of such an ECLSS will be a challenge because only limited resources like payload mass and power are available. Therefore, an optimized system is necessary. For the selection of the ECLSS, an iterative multi-criteria system analysis of the safety, reliability and technology readiness level of different life support technologies were performed in conjunction with an equivalent system mass (ESM) analysis. To offset the static character of the ESM analysis, an initial transient (one day) analysis of the systems was performed based on a tradeoff for 6 different crew schedules. For this, a new tool was developed, called Life Support Trade Off Tool (LiSTOT). With the help of this spreadsheet tool, trade analyses can be made within a short time. Overall 37 different technologies were initially compared with each other and down selected to yield the optimum arrangement based on the initially variables. The variables are crew size, mission duration, pressurized volume, payload mass, and selected crew schedule. To ensure that the developed system remains feasible in a more realistic dynamic environment, a detailed model of the ECLSS was created in Virtual Habitat. Virtual Habitat is a simulation tool of the Technical University of Munich that was already used to successfully model the ISS ECLSS. This model was then used to dynamically simulate a journey to Mars. The results show, that a feasible ECLSS is possible with the made assumptions and constraints. For a one-hundred-person crew only a system which stores all necessary consumables is technically feasible. This is necessary since the power consumption for a recycling system of such a large system would be higher than the power capability of the vehicle. This derives a vast drawback on the required mass and volume. It is recommended, that additional power and thermal heat rejection resources are installed to reduce the mentioned disadvantages. «