By the time you read this, NASA’S Cassini space­craft will be but a mem­ory – va­por­ized into noth­ing­ness 1.2 bil­lion kilo­me­tres from home. But dry your tears: Sci­en­tists will be por­ing over its nearly 20-year life and 13-year so­journ around Saturn for years

StarMetro Halifax - - METRO SCIENCE -

WHY CASSINI MUST DIE: To pro­tect the pre­cious alien life that might lurk on Saturn’s moons — or could one day — Cassini is sacri ic­ing it­self for the sake of science. The plucky lit­tle probe found wa­ter on one of Saturn’s moons and or­ganic soup on an­other. Left to sput­ter out on its own, it could crash into one of those worlds and pol­lute it with Earth germs, in­tro­duc­ing the worst in­va­sive species ever. So NASA de­cided it must let Cassini or­bit closer and closer un­til it gets pulled into Saturn it­self. Its last lit­tle bit of fuel will keep its an­tenna pointed at Earth for as long as pos­si­ble as it trans­mits data on Saturn’s low­ly­ing clouds. Then it will nose­dive, lose con­tact with Earth, and burn up, be­com­ing part of the gaseous planet it so du­ti­fully stud­ied for 13 years. 2016 Of the mil­lions of dust grains Cassini sam­ples around Saturn, it inds 36 that ap­pear to be from worlds be­yond our so­lar sys­tem.


Cassini ilms Saturn’s spinning po­lar hexagon: a six-sided jet stream churn­ing at the planet’s north pole. As Saturn’s 30-year or­bit around the sun pro­gresses, the light changes and the vor­tex changes colour from blue to golden. 2006 Cassini sees the moon Ti­tan’s hazy at­mos­phere of meth­ane, the same hy­dro­car­bon gas found in hu­man farts. Ti­tan has a meth­ane cy­cle like Earth’s wa­ter cy­cle, with meth­ane oceans, clouds and rain. 2005 The Huy­gens probe para­chutes o Cassini onto Saturn’s moon Ti­tan. It beep-boops around for just 90 min­utes, snap­ping pic­tures of the hazy orange sky and peb­bly land­scape. 2006 2014 Wa­ter vapour and salt are seen spew­ing from gey­sers on the moon Encedalus, sup­ply­ing raw ma­te­rial for one of the rings. Cassini later an­a­lyzes the moon’s ice grains and sci­en­tists con­clude they came from a warm, salty, sub­sur­face ocean of liq­uid wa­ter.

2004 2008 Cassini en­ters Saturn’s or­bit. Its 12 in­stru­ments “sni ” the chem­i­cal com­po­si­tion of the at­mos­phere, mea­sure mag­netic ields and snap high-res pho­tos. The re­sults are so spec­tac­u­lar the mis­sion is ex­tended to 2017.

1998 99 Cassini swings around Venus twice, tak­ing pic­tures and pick­ing up speed due to the planet’s grav­ity.

1997 The Cassini space­craft and its Euro­pean hitch­hiker, the Huy­gens probe, blast o from Cape Canaveral, Fla.

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