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\nA technician places a nearly 70 kg parachute designed for ESA and Roscosmos\u2019s ExoMars 2020 mission<\/a> inside the dry heater steriliser of the Agency\u2019s Life, Physical Sciences and Life Support Laboratory<\/a>, based in its Netherlands technical centre.\n<\/p>\n \nMars is a potential abode of past and perhaps even present-day life. Accordingly, international planetary protection regulations require any mission sent to the Red Planet to undergo rigorous sterilisation, to prevent terrestrial microbes from piggybacking their way there<\/a>.\n<\/p>\n \nThe Lab\u2019s Alan Dowson explains: \u201cThis is the \u2018qualification model\u2019 of the 35-m diameter main parachute for ExoMars 2020, basically a test version which allows us to finalise our sterilisation procedures ahead of the flight model chute\u2019s arrival.\n<\/p>\n \n\u201cThis version has been threaded with thermal sensors, allowing us to see how long it takes to reach the required sterilisation temperature in all parts of the folded parachute, even in the hardest to heat points. Our target was to sterilise at 125 \u00b0C for 35 hours and 26 minutes, and the oven took about 44 hours to reach that temperature to begin with.\u201d\n<\/p>\n \nThe oven is part of the Lab\u2019s 35 sq. m \u2018ISO Class 1\u2019 cleanroom, one of the cleanest places in Europe. All the cleanroom\u2019s air passes through a two-stage filter system. Anyone entering the chamber has to gown up in a much more rigorous way than a hospital surgeon, before passing through an air shower to remove any remaining contaminants.\n<\/p>\n \n\u201cIf you imagine our clean room as being as big as the entire Earth\u2019s atmosphere, then its allowable contamination would be equal to a single hot air balloon,\u201d adds Alan. \u201cOur ISO 1 rating means we have less than 10 dust particles measuring a tenth of one millionth of a metre in diameter per cubic metre of air.\u201d\n<\/p>\n \nThe mostly nylon and Kevlar parachute, packed into an 80-cm diameter donut-shaped unit, was delivered by Italy\u2019s Arescosmo<\/a> company. This qualification model will now be sent back there for testing, to ensure this sterilisation process causes no change to the parachute\u2019s material properties.\n<\/p>\n \nAlan explains: \u201cWe will receive the parachute flight model later this spring for the same sterilisation process \u2013 identical to this version, except without any thermal sensors.\u201d\n<\/p>\n \nExoMars\u2019s smaller first stage 15-m diameter parachute has already gone through sterilisation using the oven. This is the parachute that opens during initial, supersonic atmospheric entry, with the second, larger chute opening once the mission has been slowed to subsonic velocity<\/a>.\n<\/p>\n \nThe Lab has also tackled a variety of ExoMars instruments and subsystems, but this second stage subsonic parachute is the single largest item to be sterilised. The sterilisation process aims to reduce the overall mission \u2018bioburden\u2019 to a 10 thousandth of its original level.<\/p>\n","protected":false},"excerpt":{"rendered":" \nA technician places a nearly 70 kg parachute designed for ESA and Roscosmos’s ExoMars 2020 mission<\/a> inside the dry heater steriliser of the Agency’s Life, Physical Sciences and Life Support Laboratory<\/a>, based in its Netherlands technical centre.\n<\/p>\n \nMars is a potential abode of past and perhaps even present-day life. Accordingly, international planetary protection regulations require any mission sent to the Red Planet to undergo rigorous sterilisation, to prevent terrestrial microbes from piggybacking their way there<\/a>.\n<\/p>\n \nThe Lab’s Alan Dowson explains: “This is the ‘qualification model’ of the 35-m diameter main parachute for ExoMars 2020, basically a test version which allows us to finalise our sterilisation procedures ahead of the flight model chute’s arrival.\n<\/p>\n \n“This version has been threaded with thermal sensors, allowing us to see how long it takes to reach the required sterilisation temperature in all parts of the folded parachute, even in the hardest to heat points. Our target was to sterilise at 125 °C for 35 hours and 26 minutes, and the oven took about 44 hours to reach that temperature to begin with.”\n<\/p>\n \nThe oven is part of the Lab’s 35 sq. m ‘ISO Class 1’ cleanroom, one of the cleanest places in Europe. All the cleanroom’s air passes through a two-stage filter system. Anyone entering the chamber has to gown up in a much more rigorous way than a hospital surgeon, before passing through an air shower to remove any remaining contaminants.\n<\/p>\n \n“If you imagine our clean room as being as big as the entire Earth’s atmosphere, then its allowable contamination would be equal to a single hot air balloon,” adds Alan. “Our ISO 1 rating means we have less than 10 dust particles measuring a tenth of one millionth of a metre in diameter per cubic metre of air.”\n<\/p>\n \nThe mostly nylon and Kevlar parachute, packed into an 80-cm diameter donut-shaped unit, was delivered by Italy’s Arescosmo<\/a> company. This qualification model will now be sent back there for testing, to ensure this sterilisation process causes no change to the parachute’s material properties.\n<\/p>\n \nAlan explains: “We will receive the parachute flight model later this spring for the same sterilisation process – identical to this version, except without any thermal sensors.”\n<\/p>\n<\/p>\n