{"group":"make","pic":"living/pics/computers-city.webp","question":"Why can't Mars just ask Earth's computers?","answer":"Because Earth is light-minutes away. Everything that keeps people safe thinks right here, in a quiet hall under the soil, and AI lets a small town run a city's worth of machines.","play":{"label":"Watch the radar","href":"play/"},"earth_mars":{"earth":{"head":"Answers in a blink"},"mars":{"head":"The city thinks for itself"},"pics":{"earth":"living/pics/em-computers-earth.webp","mars":"living/pics/em-computers-mars.webp"},"rows":[{"label":"Asking a question","icon":"signal","earth":"Your phone asks a data centre and hears back in a blink.","mars":"Any answer from Earth takes {cp_rt_lo} to {cp_rt_hi} minutes, so the answers live here."},{"label":"Radiation","icon":"rad","earth":"Thick air shields every chip.","mars":"One particle from space can flip a bit in a computer's memory."},{"label":"Cooling","icon":"air","earth":"Fans blow air through the racks.","mars":"The air is only {cp_dens}% as dense as Earth's, so liquid carries the heat instead."}]},"pin":[0.38,0.52],"bits":{"title":"One particle, one flipped bit","line":"Tap the memory chip to send a particle from space through it, and watch the city's memory catch the mistake.","flipped":"Flipped by a particle","fixed":"Found and fixed","hint":"Tap the chip"},"steps_title":"Inside the server hall","steps":[{"title":"Watch from the corridor","text":"Nobody works inside. Visitors watch the racks through a long window from a warm corridor."},{"title":"Racks in dry gas","text":"The hall is sealed and filled with {cp_gas}, so nothing rusts and nothing burns."},{"title":"A robot does the swaps","text":"A robot on a ceiling rail lifts out a failed part and passes it through a small lock."},{"title":"Heat for the farm","text":"Liquid loops carry the heat to the farm next door, where it keeps the crops warm."}],"kinds":{"title":"Three kinds of computer","line":"Each kind does one job, and the ones that keep you alive answer to nobody outside.","list":[{"id":"ctl","name":"Controllers","text":"Small, tough computers in pairs that run the air, the airlocks and the reactors, on their own wires. No message from outside can reach them."},{"id":"hall","name":"The server hall","text":"Ordinary servers for planning, records, AI and the robots. Every job that matters runs on two machines that compare answers."},{"id":"you","name":"In your hand","text":"Phone-class chips in suits, rovers, robots and tablets."}],"earth":"Earth: only for work that can wait","gap":"No wire to the outside"},"heat":{"title":"Heat that grows food","line":"Every watt a computer uses ends up as heat. Here, the farm gets it first.","hall":"Server hall","farm":"Farm vault","rad":"Radiators on the surface","text":"The city's computers use {cp_kw_lo} to {cp_kw_hi} kW for every person, day and night. Liquid loops carry that heat to the farms and homes, and only what is left goes up to the radiators."},"scene":{"pic":"living/pics/scene-computers.webp","look":"03-16","shot":"cutaway","focus":"50% 60%","zoom":1.6,"spots":[{"at":[0.18,0.64]},{"at":[0.43,0.7]},{"at":[0.5,0.5]},{"at":[0.68,0.6]}]},"proof":{"pic":"living/people/computers-proof.webp","place":"Jezero crater, Mars","when":"2023","head":"A phone chip that flew on Mars","credit":"Photo: NASA/JPL-Caltech/ASU/Simeon Schmauß (CC BY 2.0)"},"fact":"Ingenuity, the first helicopter on another world, flew on a phone processor running at {cp_ing_ghz} GHz. It was built for {cp_ing_plan} test flights and flew {cp_ing_flights} times.","quiz":[{"q":"What can one particle from space do to a computer?","a":["Flip a bit in its memory","Melt its chips","Wipe all its memory at once"],"why":"One charged particle can change what a single memory cell holds. Memory that finds and fixes flipped bits catches it.","more":"On {cp_cur_date}, corrupted memory stopped Curiosity's main computer. Engineers switched to its spare; a cosmic ray was the likely cause.","cite":"03-16 F-09, F-10","from":"problem","fig":0,"icon":"rad"},{"q":"Why does nobody work inside the server hall?","a":["It is sealed and filled with dry gas","It is too loud","It is kept below freezing"],"why":"The hall is filled with {cp_gas}. Robots swap parts through a small lock, and people watch through a window.","more":"Microsoft once sank {cp_nat_srv} servers off Orkney in a sealed tube of dry nitrogen. They failed at one {cp_nat_x}th the rate of the same servers on land.","cite":"03-16 CP-05, F-18","from":"fix","fig":0,"icon":"chip"},{"q":"Where does the heat from the computers go first?","a":["To the farms and homes next door","Straight out into the air","Down into the ice"],"why":"Liquid loops carry the heat to the farms first. Only what is left goes to radiators on the surface.","more":"Since {cp_od_since}, spare heat from Meta's data centre in Odense, Denmark, has warmed more than {cp_od_homes} homes.","cite":"03-16 CP-06, F-15","from":"why","fig":1,"icon":"leaf"}],"notes":[{"beat":"fix","text":"Curiosity's main computer runs at just {cp_rad_mhz} MHz, built to shrug off radiation rather than to be fast.","cite":"03-16 F-06"}],"everyday":{"title":"A day with the city's mind","items":[{"time":"07:10","head":"Ask it anything","text":"Over breakfast you ask the town's AI how the tomatoes are doing. It answers at once, in plain words, from right here.","tag":"No wait for Earth","pic":"living/pics/computers-city.webp","pos":"60% 50%"},{"time":"11:45","head":"The robots' to-do list","text":"While you work, the AI plans the robots' day: which trench to dig, which panel to dust. A person says yes.","tag":"People decide","pic":"living/pics/scene-construction.webp","pos":"15% 55%"},{"time":"21:00","head":"Warm all night","text":"The day's thinking ends up as heat in the farm next door, keeping the crops warm until morning.","tag":"{cp_kw_lo} to {cp_kw_hi} kW a person","pic":"living/pics/computers-far.webp","pos":"70% 50%"}]},"living":"The city's computers live in a cold, quiet hall under the soil, and you hardly ever think about them. Ask a question and the answer comes straight back from right here, and all that thinking keeps the farm next door warm.","from":"From the corridor window","later":{"pics":{"city":"living/pics/computers-city.webp","far":"living/pics/computers-far.webp"},"city":{"tag":"One hall","text":"One sealed hall beside the farms runs the town's planning, records, AI and robots."},"far":{"tag":"Two halls","text":"Two halls far apart keep every answer twice, and their heat warms orchards under water roofs."}}}