{"group":"port","pic":"living/pics/pads-city.webp","question":"Where does a ship the size of a tower touch down?","answer":"On a round pad of Mars soil baked into stone, a few kilometres out on the plain and downwind, so the dust of every landing blows away from home.","play":{"label":"Watch a ship land","href":"play/?at=360,360,-2.19,0.22,28&era=city&light=day"},"plume":{"title":"When the flame hits the ground","line":"Pick the ground and watch what a landing does to it.","modes":[{"name":"Loose dust","text":"The flame digs straight in. In lab tests at Mars air pressure, a crater formed in under a second and grit flew far and fast.","big":"{pd_crater} m","unit":"crater in under a second"},{"name":"Baked pad","text":"The flame spreads flat over hard stone. Only a thin skin of dust races out, and the berms catch it.","big":"{pd_berm} m","unit":"berms catch the dust"}]},"parts_title":"What makes a pad","parts":[{"icon":"heart","title":"The baked heart","text":"Six-sided pavers of Mars soil, baked at about {pd_sinter}°C into stone. {pd_inner} m across."},{"icon":"ring","title":"The light ring","text":"A smooth outer ring out to {pd_outer} m, edged with lights that guide each ship down."},{"icon":"berm","title":"The berms","text":"Banks of soil {pd_berm} m high round a {pd_apron} m gravel apron catch whatever the flame throws."},{"icon":"crew","title":"The pad crew","text":"Two crew and their robots sweep, patch and rake after every landing."}],"above":{"title":"The pad from above","sub":"Drawn to scale, with a football pitch for size.","line":"A landing pad from above, its rings drawn to scale with a ship's footprint and a football pitch.","heart":"Baked heart","ring":"Outer ring","berm":"Berm","pitch":"Football pitch","ship":"Ship and landing error","scale":"Drawn to scale"},"wind":{"title":"Why the port stands out on the plain","town":"Town","pad":"Nearest pad","farm":"Tank farm","wind":"Dusty winds blow this way","starbase":"Starbase village to its pads","line":"The nearest pad stands {pd_port} km from town and downwind, with the tank farm {pd_farm} km beyond it, so a landing's dust always blows away from home."},"earth_mars":{"earth":{"head":"Rockets come down on concrete"},"mars":{"head":"Ships come down on baked stone"},"pics":{"earth":"living/pics/em-pads-earth.webp","mars":"living/pics/em-pads-mars.webp"},"rows":[{"label":"The ground","icon":"layers","earth":"Thick concrete, poured by the truckload.","mars":"Loose fine dust, baked into stone pavers by robots before anyone lands."},{"label":"Neighbours","icon":"house","earth":"At Starbase in Texas, the village stands about {pd_sb_km} km from the pads.","mars":"Arcadia's nearest pad stands {pd_port} km out and downwind, so landing dust blows away from home."}]},"living":"Landing day is the best day of the season. Work outside pauses, the whole town gathers at the screens and the viewing rooms, and a new ship settles onto its pad on a clear blue-violet flame. A few days later the sweepers have the pad ready for the next one.","fact":"On {pd_f9}, a rocket stage flew back from space and landed upright on a flat pad at Cape Canaveral: the first time an orbital rocket's first stage had ever come home that way. Every ship at Arcadia lands like it.","later":{"pics":{"city":"living/pics/pads-city.webp","far":"living/pics/pads-far.webp"},"city":{"tag":"{pd_city_lo} to {pd_city_hi} pads","text":"The port grows a pad at a time round its arc, so one can be swept and patched while ships land on another."},"far":{"tag":"Four pads","text":"Four pads stand out on the plain, and ships come and go every window, their landing lights chasing round each baked heart at dusk."}},"pin":[0.66,0.73],"scene":{"pic":"living/pics/scene-pads.webp","look":"03-02","shot":"dusk","focus":"50% 60%","spots":[{"at":[0.47,0.74]},{"at":[0.73,0.68]},{"at":[0.12,0.56],"side":"left"},{"at":[0.8,0.81]}]},"proof":{"pic":"living/people/pads-proof.webp","place":"Landing Zone 1, Cape Canaveral, Florida","when":"{pd_f9}","head":"The first rocket to come home","credit":"Photo: SpaceX (CC0, public domain)"},"quiz":[{"q":"Why does the port stand kilometres from town?","a":["So landing dust blows away from home","Ships are too loud to land near people","The ground near town is too soft"],"why":"The port lies {pd_port} km out and downwind, so the dust a landing throws blows away from the town.","more":"Kennedy's two big launch pads were built {pd_ksc} m apart, so trouble on one could never reach the other.","cite":"03-02 P-01, 04-01-01 FC-02, F-03","from":"problem","fig":0,"icon":"globe"},{"q":"What is the pad's hard heart made of?","a":["Mars soil baked into pavers","Concrete shipped from Earth","Steel plates"],"why":"Robots bake Mars soil into six-sided pavers at about {pd_sinter}°C, hard enough to take a landing.","more":"In Hawaii in 2015, a NASA team and a rover laid {pd_pavers} pavers of baked local rock into a pad {pd_pisces} m across, with no glue at all.","cite":"03-02 F-06, P-03","from":"fix","fig":0,"icon":"layers"},{"q":"How wide is the pad's baked heart?","a":["{pd_inner} m, more than twice the ship","Exactly as wide as the ship","Half a kilometre"],"why":"The heart is {pd_inner} m across: room for a ship {pd_ship_w} m wide to land up to {pd_err} m off its mark.","more":"The very first ship had no pad at all. It landed on the best natural ground orbit could find, and its scorch mark is still there.","cite":"03-02 F-10, F-14, P-08","from":"why","fig":0,"icon":"target"}],"notes":[{"beat":"fix","text":"Gaps between pavers are a weak spot: exhaust forced into a joint can lift a paver like wind under a loose roof tile. So the heart is laid tight and patched after every landing.","cite":"03-02 F-13, F-16"}],"from":"From the port","everyday":{"title":"A landing day","items":[{"time":"06:40","head":"A ship on the way","text":"The approach is clear, work outside pauses, and the town gathers round the screens to watch it come in.","tag":"{pd_port} km out","pic":"living/pics/em-pads-mars.webp","pos":"65% 50%"},{"time":"07:15","head":"Touchdown","text":"Six legs settle onto the baked heart on a pale blue-violet flame. A ring of dust races out and stops at the berms.","tag":"{pd_berm} m berms","pic":"living/pics/scene-pads.webp","pos":"45% 55%"},{"time":"16:30","head":"The sweepers go out","text":"Two crew and their robots sweep, patch and rake, and the pad is ready for the next ship.","tag":"{pd_reset} days to reset","pic":"living/pics/pads-city.webp","pos":"50% 45%"}]}}