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02.08.2001  |  125× přečteno      vytisknout článek

Pouze Anglicky

Want to make it to Mars and back? Prepared to put up with crap food? Astronauts making a Mars mission could be facing a somewhat unappetising menu ? consisting of their own waste products. A potential Mars trip ? which scientists estimate would take up to 3 years - will require travellers to equip themselves with oxygen, water and food. Unlike previous space missions, much of that food will have to be ultimately recycled from the astronauts own by-products. Introducing MELISSA. MELISSA (Micro-Ecological Life Support Alternative) is the name given to the recycling system being developed by a team of scientists the European Space Agency (ESA), which uses micro-organisms to process human waste. The fermented waste can then be used to grow plants, which can in turn produce food, oxygen and water. While previous space missions have utilised systems that recycled air and water, MELISSA is deemed essential if humans are to travel successfully to Mars. According to Chris Savage from ESA, the trip would be the difference between sailing on a little puddle of water, and navigating the Atlantic. Inner-workings MELISSA is essentially an artificial ecosystem, comprising five separate stages. The first area concentrates on liquefying the waste products produced by the space travellers. Christophe Lasseur from the MELISSA project team in The Netherlands explains MELISSA is "a bit like a lake." At the bottom is sludge [raw waste] that undergoes anaerobic fermentation in darkness. As the recycling process continues, waste is progressively broken down using first light, then oxygen and finally carbon dioxide ? just as a lake or river on earth does. In the fourth stage, plants will be grown using the fermented waste products from the first three stages. The final, fifth stage, is where the astronauts will live, sustaining themselves on oxygen and food produced by the plants from the stage below. The entire system has to be large enough to produce sufficient plant life to support the pioneering Martian explorers, but compact and efficient enough to be contained in the Mars spacecraft. European researchers are busy assembling MELISSAs first three stages, for the purpose of building a pilot plant outside Barcelona, Spain. In addition to MELISSAs European development, specialists in Guelph, Canada recently unveiled the fourth stage of the process. Onlookers witnessed what appeared to be a brightly lit industrial refrigerator with tomato plants inside. This is MELISSAs trump card, and is the stage where the human waste becomes a usable product ? the plants the astronauts will rely upon for food and oxygen. The conditions at the Canadian site have been modified to closely represent those on Mars, with very low atmospheric pressure ? only one percent of that on Earth. The real test will come when scientists work out whether plants can survive at such a staggeringly low pressure, which is what MELISSAs team hopes to determine. Recycling waste By 2005 the pilot should be fully operational with all five compartments from around the world working together. The first living creatures to sample MELISSAs capabilities will be three rats, which will live in MELISSAs fifth and final compartment ? just as the astronauts will eventually do. The rats produce roughly the equivalent carbon dioxide output of one human, and require the same oxygen demands, and should give researchers an idea as to what the astronauts will require. After the rat trials are complete, MELISSAs team will start trials with actual humans. Like the rats, the humans will live inside MELISSAs fifth stage, effectively enclosing themselves in a living, growing ecosystem. According to initial projections, MELISSAs size is dependent on the number of astronauts inside and the quality of food grown. About 10 square metres of growing area is needed if the astronauts are to live on wheat, but much less is needed if the users can stomach a more efficient, if somewhat less palatable diet of algae. MELISSAs first consumers MELISSAs development is only one answer to the many problems facing cosmonauts on a mission to Mars ? a mission some experts believe may be possible within the next 10 years. Scientists at NASA are acutely aware of the impossibility of providing medical care to the space travellers once they have embarked upon the long journey. Spacecraft have no way of accommodating complex diagnostic or treatment equipment, and at this stage scientists cant even tell whether broken bones could heal in microgravity, so ways need to be devised for astronauts to be able to treat themselves if necessary. Additionally, astronauts need to be psychologically prepared to spend lengthy periods of time in space, a directive that could lead to feelings of depression or even aggression. Space travellers also risk increased exposure to dangerous space radiation, which would be augmented by the extended time needed for a spacecraft to reach Mars. But for the time being at least, and for those with the stomach for it, it looks like MELISSA could provide one crucial piece in the puzzle in the race to take humans to Mars. Zdroj: www.beyond2000.com

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