{"group":"survive","pic":"living/pics/water-city.webp","question":"Where does a city in a desert get its water?","answer":"From ice frozen under the plain for millions of years. Every drop the city drinks, breathes and burns starts down there.","play":{"label":"Run the ice mine","href":"play/#mine"},"ground":{"title":"The ground under your boots","line":"Drag the drill down through the plain.","drag":"Drag to drill","depth":"m down","layers":[{"id":"dry","name":"Dry soil","text":"A crust of dust and soil keeps the ice from the open air, which would turn it straight to vapour."},{"id":"ice","name":"Ice-rich ground","text":"Up to {ice_pct}% ice, frozen tens of millions of years ago. About {w_base_storeys} storeys deep."},{"id":"old","name":"Old, hard ground","text":"Rock over ancient lava plains. No ice worth mining."}],"well":"The well reaches {rw_depth} m: {w_well_storeys} storeys straight down.","pool":"The melt pool","house":"A two-storey home, to scale","dry_tag":"Only {ice_top} m thick"},"steps_title":"How a well works","steps":[{"icon":"drill","title":"Drill","text":"A steel tube unrolls from a drum and bores straight down. Gas blows the chips back up."},{"icon":"melt","title":"Melt","text":"A heater melts a pool of water deep inside the ice."},{"icon":"pump","title":"Pump","text":"Water comes up. Some is warmed and sent back down, so the pool grows and sinks."},{"icon":"clean","title":"Clean","text":"Filters, salt tests, reverse osmosis and ultraviolet light make it safe to drink."}],"energy":{"title":"Lifting is easy. Melting is hard.","lift":"1 dot: lifting a litre {rw_depth} m up the well","melt":"Every dot: melting that litre","line":"Melting ice takes over {w_melt_x} times the energy of lifting it up the well, before it is even warmed. A Mars well is mostly a heater, kept warm by the reactors' spare heat.","sub":"One dot is the energy to lift a litre of water up the well. Watch what it takes to melt it.","tags":{"lift":"Lifting it","melt":"Melting it"}},"earth_mars":{"earth":{"head":"Water falls from the sky"},"mars":{"head":"Water hides as ice underground"},"pics":{"earth":"living/pics/em-water-earth.webp","mars":"living/pics/em-water-mars.webp"},"rows":[{"label":"Where it comes from","icon":"drop","earth":"Rain fills rivers, lakes and reservoirs.","mars":"Ice frozen under the plain: the ground is up to {ice_pct}% ice."},{"label":"On the surface","icon":"wave","earth":"Oceans cover {earth_water_pct}% of the planet.","mars":"The air is only {air_pct}% as thick as Earth's, so water freezes or turns straight to vapour."}]},"living":"Every glass of water here was ice, frozen under the plain for millions of years before the city woke it up. It runs clean from every tap, and the same water keeps going round: from your tap to the farms, into the air you breathe, and back again.","fact":"The same kind of well has watered the South Pole research station since {sp_since}. It melts about {sp_gal} US gallons a year from the ice under the base.","card":"water","pin":[0.88,0.47],"scene":{"pic":"living/pics/scene-water.webp","look":"03-01","shot":"cutaway","focus":"40% 50%","ar":1.778,"spots":[{"at":[0.262,0.125],"side":"left"},{"at":[0.58,0.6],"zoom":2.6},{"at":[0.362,0.6],"zoom":3.2},{"at":[0.462,0.12]}]},"proof":{"pic":"living/people/water-proof.webp","place":"Amundsen-Scott South Pole Station, Antarctica","when":"Every day since {sp_since}","head":"A well under the South Pole","credit":"Photo: Bill Spindler, U.S. Antarctic Program, National Science Foundation (public domain)"},"quiz":[{"q":"What uses most of a Mars well's energy?","a":["Melting the ice","Lifting the water up the well","Cleaning it to drink"],"why":"Melting ice takes over {w_melt_x} times the energy of lifting it {rw_depth} m up the well.","more":"At the South Pole the same kind of well has melted a pool about {wq_pool_w} m across and {wq_pool_d} m deep in the ice under the station.","cite":"03-01 F-10, F-11, F-28","from":"why","fig":0,"icon":"bolt"},{"q":"Why is Arcadia's ice buried under a crust of soil?","a":["Open air would turn it straight to vapour","Dust storms blew soil over it last year","The first settlers covered it to keep it clean"],"why":"The air is so thin that bare ice turns straight to vapour. Only ice under a crust of soil has lasted.","more":"In Greenland, water from the same kind of well tested purer than water distilled three times in glass, and people drank it without filtering it.","cite":"02-05 F-09, 03-01 F-21","from":"problem","fig":0,"icon":"layers"},{"q":"How deep does a Mars well reach?","a":["{rw_depth} m, about {w_well_storeys} storeys","Just under the surface","More than a kilometre"],"why":"The well reaches {rw_depth} m: {w_well_storeys} storeys straight down, into the ice.","more":"No well lasts for ever. Camp Century's first well in Greenland was retired after about {wq_cc_gal} million gallons, at over {wq_cc_ft} feet deep, and a new hole was drilled nearby.","cite":"03-01 F-04, F-24","from":"problem","fig":0,"icon":"well"}],"notes":[{"beat":"fix","text":"A well can be shut down, left to freeze and melted again later. Camp Century and the South Pole station have both done it.","cite":"03-01 F-25"}],"from":"From the well field","everyday":{"title":"A day with water","items":[{"time":"07:30","head":"Fresh from the tap","text":"Your morning glass was ice under the plain for millions of years. The wells melt it, clean it and pipe it to every home.","tag":"{rw_depth} m down","pic":"living/pics/water-city.webp","pos":"30% 60%"},{"time":"12:15","head":"The air you breathe","text":"Electricity splits water into hydrogen and oxygen. The oxygen in the room around you started as ice.","tag":"O₂ from water","pic":"living/pics/scene-water.webp","pos":"45% 70%"},{"time":"18:40","head":"A ship fuels for home","text":"Out at the port a ship fills up for the trip to Earth, its fuel made from water and the Martian air.","tag":"{w_ship_t} t a ship","pic":"living/pics/water-far.webp","pos":"60% 40%"}]}}