Browsing by Author "Fontaine, Jean-Pierre"
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Item Main focusses on the use of higher plant growth models for life support systems(51st International Conference on Environmental Systems, 7/10/2022) Ku?ma, Joanna; Fontaine, Jean-Pierre; Poulet, Lucie; Dussap, Claude-GillesIn long-term plans for space exploration investigated by major space agencies, the exploration of the Moon or Mars involves solving many technological problems. One of them is the development of an efficient and robust life-support system. One-way trip to Mars will take between 6 to 8 months with current technology. According to NASA�s economic calculations, for each trip over 10 months, at least 15% of the food for astronauts should be produced onboard. To make this possible it is necessary to switch from physicochemical (PC) systems in charge of recycling water and oxygen and stabilization of waste - like the one on the International Space Station - to hybrid ones where part of the system can be based on PC technology and part of it on biological processes in order to produce edible biomass, e.g. to grow plants. As the growth and development of higher plants are strongly influenced by the environmental conditions, bio-regenerative life-support systems require a high level of control and management. In systems that include plants, it is possible to use transpiring water as a source of potable water, which in turn can reduce the need for physical purification systems. For this to be possible, it is necessary to understand in-depth how the various parameters affect the plant growth and transpiration process - especially in closed systems. Most of the existing plant growth models do not consider gravity, radiation, or CO2 concentration as variable parameters. However, over the years, new models are being developed in controlled environments. This article presents an overview of the existing models with a focus on the ones that can be used to simulate systems in space. The article also highlights the work that still needs to be done to understand the impact of certain parameters on plant growth for a closed-systems application.Item Modelling Higher Plants Gas Exchange in Reduced Gravity Environment(47th International Conference on Environmental Systems, 2017-07-16) Poulet, Lucie; Dussap, Claude-Gilles; Fontaine, Jean-PierreLong-duration human space missions and the establishment of permanent off-Earth bases (e.g. on the Moon or Mars) is one of the main focuses of today’s space exploration. This poses many severe challenges at the life-support level, which needs to recycle atmosphere, water and waste for crew survival. The European Space Agency (ESA) project Micro-Ecological Life Support System Alternative (MELiSSA) can ensure these functions. It is a closed-loop bio-regenerative life-support system functioning with microorganisms and higher plants and providing a circular cycling of mass, including O2 production, CO2 capture, water recycling and food production. The growth and development of higher plants are strongly influenced by environmental conditions (e.g. gravity, pressure, temperature, relative humidity, partial pressure of O2 or CO2) so bio-regenerative life support systems require a high level of control and management. The goal is to develop a mechanistic physical model of plant growth to predict the effects of microgravity or of a reduced gravity environment (like on Mars or on the Moon) on plant growth at its morphological, physicochemical and biochemical levels. Current existing plant growth models are developed for agronomy and are therefore not adapted for modeling plant growth for applications in life-support systems, which require being able to extrapolate plants behavior for a wide range of environmental conditions. The first mechanistic plant growth model developed in the framework of the MELiSSA project has attempted to address these limitations. Based on this work, a preliminary structure of the model was defined. In this presentation, the addition of gravity as a parameter is addressed, taking into account the altered gas exchanges due to the low or lack of free convection in reduced gravity environments. The influences of forced and free convection are studied according to the levels of gravity and the interdependence of low gravity and ventilation are addressed.