{"group":"shelter","pic":"living/pics/suits-city.webp","question":"How do you step out onto Mars, and come home without bringing it in?","answer":"Through a porch and an airlock. Your suit carries a bubble of air to walk in, and the porch's brushes, grille and lock leave the dust outside.","play":{"label":"Walk to the court's airlock","href":"play/?at=0,-62,0,0.22,12&era=city&light=day"},"dust":{"title":"Dust that clings","line":"Watch the plain's dust blow onto a suit's leg, then switch on the dust shield.","facts":[{"icon":"spark","name":"Fine as smoke","text":"Grains about {dust_d} µm across, far finer than flour, carried on the lightest wind."},{"icon":"bolt","name":"Charged","text":"Rubbed by the wind, the grains carry a charge that makes them cling to everything they touch."},{"icon":"target","name":"Magnetic","text":"Mars Pathfinder's magnets gathered a coat of dust in {pf_year}: the grains are cemented with iron oxide."}],"shield_on":"Switch on the dust shield","shield_off":"Switch off the dust shield","note":"The porch's dust shields lift dust off with moving electric fields. On the Moon in {eds_year}, the same idea cleared {eds_glass}% of the dust from glass."},"porch":{"title":"The way home","steps":[{"title":"Brush down","text":"Boots are stamped on the steel grille and legs brushed clean, about {clean_min} minutes on the porch before anyone goes in."},{"title":"Dust shields","text":"Dark glass panels beside the hatch lift dust off with moving electric fields, with no water and no moving parts."},{"title":"The hatch","text":"{hatch_w} by {hatch_h} m, opening inwards so the air inside holds it shut. A ring of lights glows green when the pressure is even."},{"title":"Spare suits","text":"A rack of spares hangs under the canopy, so a suit that fails its check never keeps anyone in."}]},"rooms":{"title":"Five rooms from dust to home","line":"Every way in runs from dirty to clean. Suits and tools stay on the dust side; you walk through to the clean side in your own clothes.","stages":[{"name":"The porch","text":"Stamp, brush and blow off the dust.","tag":"Mars air"},{"name":"The airlock","text":"Room for {pair}. The air is filtered while it fills.","tag":"About {cycle_min} min a trip"},{"name":"The suit room","text":"Suits hang up to dry and get checked.","tag":"{cas_2} Pa lower"},{"name":"Clean change","text":"A wash and your own clothes.","tag":"{cas_1} Pa lower"},{"name":"Home","text":"Warm, clean and full of air.","tag":"The halls"}],"flow":"Each room is kept at slightly lower pressure than the one after it, so air always flows towards the dust, never into your home."},"press":{"title":"A bubble of air to walk in","line":"Your suit holds {suit_kpa} kPa of pure oxygen: about {suit_x} times what a body needs, and soft enough to bend as you walk.","bars":{"earth":"Earth's air","halls":"Arcadia's halls","suit":"Your suit","mars":"Mars"},"need":"What a body needs"},"cycle":{"title":"The air goes home first","line":"Before the outer door opens, the lock's air is pumped back into the town until only {recover_pct}% is left. That last bit drifts out onto the plain: about {gas_g} g a trip.","town":"The town's tanks","lock":"The airlock","mars":"Mars","kept":"Pumped back home","lost":"Let out onto the plain"},"earth_mars":{"earth":{"head":"Open the door and walk out"},"mars":{"head":"Every step out takes a suit"},"pics":{"earth":"living/pics/em-suits-earth.webp","mars":"living/pics/em-suits-mars.webp"},"rows":[{"label":"Air pressure","icon":"air","earth":"{earth_kpa} kPa at sea level: air you never even notice.","mars":"{mars_pa} Pa, about {air_pct}% of Earth's. You walk in your own bubble of air."},{"label":"Dust","icon":"spark","earth":"Heavy grains that a doormat deals with.","mars":"Grains about {dust_d} µm across, charged and magnetic, that cling to everything."}]},"living":"Going out is a few minutes through warm, bright rooms, and coming home is even better: stamp, brush, step through, hang up your suit on the dust side, wash and walk in to dinner with nothing of Mars on you but the view you have just seen.","fact":"The space station had no airlock of its own until July {quest_year}. Quest, {quest_len} m long and {quest_d} m across, has two rooms: one where the suits are kept and one from which astronauts head out.","later":{"pics":{"city":"living/pics/suits-city.webp","far":"living/pics/suits-far.webp"},"city":{"tag":"Suits wait on the wall","text":"The main ways in are suitport locks: your suit stays docked on the wall, you climb in through its back from indoors and walk off onto the plain."},"far":{"tag":"Walk-in locks","text":"The dome neighbourhoods open onto the plain through wide walk-in locks, and light, close-fitting suits take people out for an afternoon in the open."}},"pin":[0.86,0.78],"scene":{"pic":"living/pics/scene-suits.webp","look":"03-07","shot":"porch_dusk","focus":"50% 55%","spots":[{"at":[0.13,0.62]},{"at":[0.34,0.5]},{"at":[0.48,0.47]},{"at":[0.83,0.5]}]},"proof":{"pic":"living/people/suits-proof.webp","place":"International Space Station","when":"28 April 2023","head":"The station's front door","credit":"Photo: NASA Johnson Space Center (public domain)"},"quiz":[{"q":"Which way does an airlock's hatch open?","a":["Towards the side with more air","Outwards onto the plain","Sideways, like a lift door"],"why":"The air inside pushes on the hatch and holds it shut. It cannot swing open while the lock is full.","more":"On Polaris Dawn in {pol_year}, all {pol_people} crew put on suits and emptied their whole cabin in about {pol_depress} minutes: the most people ever in vacuum at once.","cite":"03-07 AD-02, F-05","from":"fix","fig":0,"icon":"helmet"},{"q":"Where does most of the airlock's air go before the outer door opens?","a":["Back into the town","Out onto the plain","Into the suits"],"why":"The lock is pumped down to {recover_pct}% of its air in about {pump_min} minutes, and only that last bit drifts out to Mars.","more":"A HEPA filter, like the ones that clean the lock's air, catches at least {hepa}% of particles {hepa_um} µm across, the hardest size of all to catch.","cite":"03-07 AD-03, F-30","from":"why","fig":1,"icon":"air"},{"q":"Why does Mars dust cling to suits?","a":["Its grains are tiny, charged and magnetic","It is damp and sticky","It freezes onto the fabric"],"why":"The grains are about {dust_d} µm across and very probably charged, and Pathfinder's magnets gathered a coat of them.","more":"NASA's dust shield cleared {eds_glass}% of the dust from glass on the Moon in {eds_year}, using nothing but moving electric fields.","cite":"03-07 F-15, F-19, F-29","from":"problem","fig":0,"icon":"spark"}],"notes":[{"beat":"fix","text":"Each main way in has {sp_per_lock} suitports: you climb into a suit docked on the wall from indoors, so the suit never comes inside.","cite":"03-07 AD-06"}],"from":"From the east porch","everyday":{"title":"A day outside","items":[{"time":"07:40","head":"Into your suit from indoors","text":"Your suit waits docked on the wall. You climb in through its back, close the hatch and step off onto the plain.","tag":"{sp_per_lock} suitports a lock","pic":"living/pics/suits-city.webp","pos":"30% 50%"},{"time":"11:30","head":"Out in pairs","text":"A shift on the plain runs about {outing_h} hours, always with a partner at your side and the city in sight.","tag":"{outing_h} h outside","pic":"living/pics/em-suits-mars.webp","pos":"28% 50%"},{"time":"18:20","head":"Home by dusk","text":"Stamp, brush and step through as the porch lamp comes on. Mars stays outside; you walk in to dinner.","tag":"{clean_min} min on the porch","pic":"living/pics/scene-suits.webp","pos":"40% 55%"}]}}