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The Environmental Control and Life Support (ECLS) equipment is one of the most sensitive subsystems aboard a manned spacecraft and the ECLSS envisaged for oncoming European programs such as Columbus or Hermes will be very complex in nature. Its development relies on the intense use of computer software during all phases of design and operations. A modern ECLS system consists of a variety of components and assemblies and contains a number of loop-type structures where components mutually influence each other. The computer software required to support the ECLSS engineer can be categorised in two groups. ‘Design Software’ is mainly employed on component and assembly level and aids the engineer in reaching the required design point. ‘Simulation Software’ is rather employed on subsystem and system level and allows to analyse a given lay-out or design and to obtain performance data for a wide range of conditions.

ECOSIM is a software tool for the simulation of Environmental Control and Life Support (ECLS) systems which has been developed for the European Space Agency. A preliminary model of the Hermes Air Management System has been developed during the ECOSIM testing in order to assess the functionality of the software and to verify its results with those obtained from previous simulation tools. The model represents the Hermes cabin with its crew and it includes submodels for the sub-systems performing the following functions: Temperature and Humidity Control. Total Pressure and Composition Control. Air revitalisation. The interactions between these different subsystem are taken into account by the model, while many of the previous simulations made assumptions to decouple the different subsystems (e.g: a constant cabin temperature has been assumed during cabin depressurization transients, to decouple the pressure control section from the air conditioning section).

The piloted Mars sprint scenario of NASA's “Humans to Mars” initiative involves round-trip “sprints” with a 2-week exploration of the Martian surface. This paper investigates the bio-isolation dynamics of plants and humans in a piloted Mars sprint. To simulate a life support system for a crew of six, a transient, thermal-network model is used. Two crops, lettuce and winged beans, are chosen for a cabin greenhouse. The crew cabin and the greenhouse are physically separated but dynamically interfaced with mass and energy flows. The plants provide the bio-regenerative portion of air, water, food, and waste cycles. The percentage of contribution by bio-regeneration to air revitalization, water reclamation, wet food supply, and waste processing functions are 9, 29, 22, and 50 percent, respectively.

This paper presents the conceptual design of a life support system sustaining a crew of six in a piloted Mars sprint. The requirements and constraints of the system are discussed along with its baseline performance parameters. An integrated operation is achieved with air, water, and waste processing and supplemental food production. The design philosophy includes maximized reliability considerations, regenerative operations, reduced expendables, and fresh harvest capability. The life support system performance will be described with characteristics of the associated physical-chemical subsystems and a greenhouse. MANNED MISSIONS TO THE PLANET MARS are included in the present NASA plans for the first decade of the next century [1]*. The first step of human exploration and eventual settlement on Mars will probably be a series of fast missions (“sprints”), with a duration of just over one year, round trip [2].