Cassini's pioneering mission ends

On Fri­day, Sep­tem­ber 15^th, the his­toric Cassini mis­sion, an inter­na­tional endeav­our, led by NASA and ESA, came to an end. The Cassini space­craft plunged into Saturn’s atmos­phere after almost 20 years in space and a 13- year-​long explo­ration of the ringed planet and its sur­round­ings.

The final sig­nal from the space­craft some 1.4 bil­lion km from Earth was received on Earth at 4:55 a.m. PDT (7:55 a.m. EDT) by NASA's Deep Space Net­work antenna com­plex in Can­berra, Aus­tralia.

After div­ing into Saturn’s atmos­phere, loos­ing con­tact with earth and burn­ing up, the Cassini space­craft became part of the planet it had been explor­ing for 13 years. The fate of the space­craft, run­ning low on rocket fuel, was delib­er­ately cho­sen to ensure Saturn’s many moons remain­ing pris­tine for future explo­rations, not get­ting con­t­a­m­i­nated by an acci­den­tal col­li­sion.

The Cassini mis­sion to Sat­urn was one of the most ambi­tious efforts in plan­e­tary space explo­ration ever under­taken. A mis­sion born from a vision in the 1990s, being the result of the inter­na­tional col­lab­o­ra­tion and effort of over 5000 sci­en­tists from 26 nations and many insti­tu­tions rev­o­lu­tion­ized our view of Sat­urn, its moons and every­thing sur­round­ing it.

Imag­i­na­tion will often carry us to worlds that never were. But with­out it we go nowhere. - Carl Sagan

"This is the final chap­ter of an amaz­ing mis­sion, but it’s also a new begin­ning,” said Thomas Zur­buchen, asso­ciate admin­is­tra­tor for NASA's Sci­ence Mis­sion Direc­torate at NASA Head­quar­ters in Wash­ing­ton. “Cassini’s dis­cov­ery of ocean worlds at Titan and Ence­ladus changed every­thing, shak­ing our views to the core about sur­pris­ing places to search for poten­tial life beyond Earth."

Cassini launched on Octo­ber 15, 1997 from Cape Canaveral in Florida. After a seven-​year jour­ney, it arrived at Sat­urn on June 30, 2004.

No mis­sion has ever explored a plan­e­tary sys­tem as rich as Saturn's in such depth for so long. - Car­olyn Porco

The mis­sion was extended twice, first for two, then for seven more years, pro­vid­ing dozens of fly­bys of Saturn's icy moons. Cassini fin­ished its tour of the Sat­urn sys­tem with its Grand Finale, a set of orbits, 22 weekly dives begin­ning in late April this year, through the roughly 1,200-mile-wide (2,000-kilometer-wide) gap between Sat­urn and its rings. No other space­craft had ever explored this region before. The Grand Finale con­cluded with the final plunge of the space­craft into the planet on Sep­tem­ber 15^th.

Cassini was a highly sophis­ti­cated space­craft and an advance over Voy­ager. Being 6.7 meters high and 4 meters wide, the Cassini space­craft was big­ger and equipped with much more sophis­ti­cated sci­en­tific instru­ments. It also car­ried the Euro­pean Space Agency’s Huy­gens probe that suc­cess­fully landed on the sur­face of Saturn’s largest moon Titan on Jan­u­ary 14, 2005, which marked the first land­ing on a moon in the outer solar sys­tem.

While the Voy­ager and Pio­neer fly­bys of the 1970s and 1980s had pro­vided only rough ideas of Saturn’s moons, Cassini dis­cov­ered pre­vi­ously unknown moons includ­ing an entire class of small bod­ies embed­ded within Saturn’s rings, solved mys­ter­ies about known ones, stud­ied their dif­fer­ences and their inter­ac­tions with the rings and made a plethora of spec­tac­u­lar new dis­cov­er­ies.

Over 13 years, Cassini has stud­ied Saturn's atmos­phere, rings and 60-​plus moons in unprece­dented detail, has beamed back to Earth hun­dreds of giga­bytes of sci­en­tific data and more than 450,000 pic­tures and enabled the pub­li­ca­tion of more than 3,000 sci­en­tific reports. The results have shifted our under­stand­ing of the solar sys­tem and redi­rected the search for life in the uni­verse.

Cassini found liquid-​methane lakes on Saturn’s largest moon Titan, the first moon in the outer solar sys­tem landed on, by Cassini’s Huy­gens probe. Titan was revealed as an Earth-​like world with rain, rivers, lakes, and seas, giv­ing rise to spec­u­la­tion about whether they might con­tain life and offer­ing an idea of what our planet might have been like before life evolved on earth.