Cassini space­craft: ‘Mag­ni­fy­ing glass’ at Saturn un­til end

Ripon Bulletin - - Nation -

CAPE CANAVERAL, Fla. (AP) — For more than a decade, NASA’s Cassini space­craft at Saturn took “a mag­ni­fy­ing glass” to the en­chant­ing planet, its moons and rings.

Cassini re­vealed wet, ex­otic worlds that might har­bor life: the moons Ence­ladus and Ti­tan. It un­veiled moon­lets em­bed­ded in the rings. It also gave us fron­trow seats to Saturn’s chang­ing sea­sons and a storm so vast that it en­cir­cled the planet.

“We’ve had an in­cred­i­ble 13-year jour­ney around Saturn, re­turn­ing data like a gi­ant fire­hose, just flood­ing us with data,” project sci­en­tist Linda Spilker said this week from the Jet Propul­sion Lab­o­ra­tory in Pasadena, Cal­i­for­nia. “Al­most like we’ve taken a mag­ni­fy­ing glass to the planet and the rings.”

Cassini was ex­pected to send back new de­tails about Saturn’s at­mos­phere right up un­til its blaz­ing fi­nale on Fri­day. Its del­i­cate thrusters no match for the thick­en­ing at­mos­phere, the space­craft was des­tined to tumble out of con­trol dur­ing its rapid plunge and burn up like a me­teor in Saturn’s sky.

A brief look back at Cassini:

TIME­LINE: Cassini rock­eted from Cape Canaveral, Florida, on Oct. 15, 1997, car­ry­ing with it the Euro­pean Huy­gens lan­der. The space­craft ar­rived at Saturn in 2004. Six months later, Huy­gens de­tached from Cassini and suc­cess­fully parachuted onto the gi­ant moon Ti­tan. Cassini re­mained in or­bit around Saturn, the only space­craft to ever cir­cle the planet. Last April, NASA put Cassini on an ever-de­scend­ing se­ries of fi­nal or­bits, lead­ing to Fri­day’s swan dive. Bet­ter that, they fig­ured, than Cassini ac­ci­den­tally col­lid­ing with a moon that might har­bor life and con­tam­i­nat­ing it.

SPACE­CRAFT: Trav­el­ing too far from the sun to reap its en­ergy, Cassini used plu­to­nium for elec­tri­cal power to feed its sci­ence in­stru­ments. Its sep­a­rate, main fuel tank, how­ever, was get­ting low when NASA put the space­craft on the no-turn­ing-back Grand Fi­nale. The mis­sion al­ready had achieved great suc­cess, and de­spite the chance of pound­ing Cassini with ring de­bris, flight con­trollers di­rected the space­craft into the nar­row gap be­tween the rings and Saturn’s cloud tops. Cassini suc­cess­fully sailed through the gap 22 times, pro­vid­ing ever bet­ter close-ups of Saturn.

RINGS: Cassini dis­cov­ered swarms of moon­lets in Saturn’s rings, in­clud­ing one called Peggy that made the short list for fi­nal pic­ture-tak­ing. Sci­en­tists wanted one last look to see if Peggy had bro­ken free of its ring. Data from the space­craft in­di­cate Saturn’s rings — which con­sist of icy bits rang­ing in size from dust to moun­tains — may be on the less mas­sive side. That would make them rel­a­tively young com­pared with Saturn; per­haps a moon or comet came too close to Saturn and broke apart, form­ing the rings 100 mil­lion years ago. Or per­haps mul­ti­ple such col­li­sions oc­curred. On the flip side, more mas­sive rings would sug­gest they orig­i­nated around the same time as Saturn, more than 4 bil­lion years ago.

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