Living in the open air, what luck ! In extreme environments like the international space Station (ISS) or a nuclear submarine, you can’t open the windows : it is necessary to breathe in a loop the same air. The filtration of the atmosphere is a challenge of every moment : “If you do nothing, you are quickly saturated with carbon dioxide “, explains François Spiero, head of foresight at the Centre national d’études spatiales (Cnes). “It recycles the air : the CO2 is partially converted into oxygen, the CO2 is captured in cartridges that are thrown then “, says the former head of human spaceflight French, in the position when Thomas Pesquet was aboard the ISS.
it is Impossible to achieve a 100% recycling but scientists do everything they can to reduce the number of vessels fueling, the launch of which is very expensive and polluting. Several times a week, the astronauts must as well change the air filter, as you change a vacuum cleaner bag filled with CO2. Sensors continually monitor the air, but, even with these precautions, everything can change every moment. During the last months of the former Russian space station Mir, the bacterial growth worsened by poor filtration systems of the air was such that the smell was pestilentielle, and the corrosion made the environment extremely hazardous. Viruses and bacteria are particularly under surveillance. “Something of benin on earth may become malignant in the space – either in the ISS or long-term habitats on the Moon or Mars – because you are in extreme conditions of temperature, pressure, gravity and radiation “, still provides François Spiero.
In a nuclear submarine, “produces oxygen”
The situation is a little less complicated under the sea. “A lot of things developed for the ISS have been adapted for modern submarines “, says Stephan Miller, the former commander of a nuclear submarine and marketing director operational Naval Group. “Unlike the ISS, we have a lot of energy through the nuclear reactor, as well as water available : it is therefore possible to produce oxygen from sea water, by hydrolysis “, details there. Side filtration, the carbon dioxide can be captured thanks to “a molecular sieve made up of microbeads in which the cavity is the size of a molecule of CO2, which remains blocked in,” says the former submariner. Heated, the CO2 is isolated and rejected in the ocean, with “environmental impact negligible,” according to the former military, as it is the result almost exclusively of the breathing of the submariners.
Read also What we breathe really
activated charcoal can also be used to capture the CO2 and other pollutants. The feminization of the sub-marine brings Naval Group to be all the more attentive to the carbon dioxide gas, which is a slightly higher concentration than normal is bearable for the crew, but strongly not recommended for pregnant women. Another challenge, specific to submarines : the batteries are continuously emitting small amounts of hydrogen and other gases, which must also be filtered. And of course, the contributions from gas outside are prohibited : wounds the ecological tolerated to earth, the shaving foams in aerosol cans are banned outright under the water !
in Addition to the installation of sensors, the engineers shall also provide for a “map of the winds” in the vessel so that no corner is confined. “You feel a light current of air all the time,” confirms Stephan Miller. Finally, when they surface, the systems of protection of the submarines against the threats of nuclear, radiological, biological and chemical (NRBC) will enable them to analyze the quality of the air before you bring it aboard.
