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A life support system on a spacecraft must provide adequate atmospheric pressure, radiation shielding, artificial gravity, air and water recycling, and food storage. The Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS) is a good model, but a completely self-sustaining system will be needed for long-duration journeys. NASA’s Biosphere and Mars on Earth (MoE) projects aim to create an efficient plant-based life support system. Shielding and simulated gravity can protect crew from radiation and weightlessness. Russian cosmonauts have extensive experience with isolation, providing valuable medical and psychological data for future missions.
A life support system on a spacecraft involves technologies designed to simulate life conditions on Earth. This includes systems necessary for basic human survival, such as adequate atmospheric pressure, radiation shielding necessary for the health threat of cosmic rays, and artificial gravity to minimize bone loss and atrophy muscles on long space missions. Other essential elements of a life support system include the ability to recycle air and water, maintain optimal heat and humidity for human comfort, and food storage and waste disposal systems.
The Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS) provides a good model of a life support system that will need to be adapted for all long manned space travel in the near future, such as a Mars. The ECLSS primarily performs the function of purifying the air on board the ISS of unwanted particulates, microorganisms and gases such as exhaled CO2 and volatile organic compounds emitted by equipment or cargo. The system also maintains proper atmospheric pressure and water vapor level, which facilitate uniform temperature and pressure throughout the station. Water is also purified by the ECLSS, along with its ability to provide fresh oxygen for breathing.
While the life support system used by the ECLSS is reliable and durable, it is not entirely self-contained. Most of the station’s water is recycled and reused numerous times, including as a source for oxygen generation, but the station still needs to be replenished with water periodically. This is partly because water is broken down to create oxygen, and the hydrogen created in the electrolysis process to do so is vented into space. Research is underway to develop a carbon dioxide reduction assembly (CReA) that will react waste hydrogen with crew exhaled CO2 to generate fresh water and methane fuel.
Long-duration journeys into deep space that could take months or years will require a completely self-sustaining, closed ecological system. One of the main components to this will be a form of power source that is more durable than the Power Supply Module (PSM) units the ISS uses to break down water and purify it, as well as provide heat, light and electricity for the station. Furthermore, it will not be possible to carry all of the water and air needed for such journeys from the outset, and regenerative equipment will be required to produce clean water and air along the way.
One of the approaches to establishing a functioning primary life support system to deliver food, air, and water has been through the Biosphere and Mars on Earth (MoE) projects sponsored by the US National Aeronautics and Space Administration (NASA). They try to simulate living conditions in an environment totally isolated from external supply. An efficient plant-based life support system created from this research could purify air and water, as well as be a source of food. NASA believes six crucial elements of life support need to be addressed in its Advanced Life Support Project (ALS). These include the management of clean food, water and air bases and the logistics of biomass, thermal and waste matters.
The long-term effects of human spaceflight can also be harmful due to radiation, weightlessness and the psychological isolation of the crew. Shielding aboard ship can protect crew from radiation in space. The rotation of a spacecraft on its central axis as it moves towards its destination can also generate a simulated level of gravity along its outer hull, due to the effects of centripetal acceleration.
Russian cosmonauts have the most extensive experience with isolation aboard space stations orbiting the Earth. In 2002, they conducted an experiment called International Space Station Crew Flight Simulation (SFINCSS) in which volunteers took turns living for eight months in a confined space. A history of long-duration missions to the Russian Mir space station is also seen as very valuable medical and psychological data. It could prove crucial in preparing for the effects any crew might encounter on a year-and-a-half mission to the planet Mars.
