25 years ago: Cassini-Huygens launches for Saturne

Reaching Saturn

Nine times wider and 95 times more massive than Earth, Saturn is a hydrogen and helium behemoth that resides far from our own plot of cosmic real estate suitable for life. Saturn’s choppy and stormy atmosphere, equatorial winds blowing at 1,100 mph (1,770 km/h), multitude of moons and unique twinkling rings – made up of trillions of unconnected particles encrusted with ice – captivated and intrigued astronomers for centuries.

In fact, two of these astronomers played such a significant role in unraveling the mysteries of Saturn that they were honored in name with a historic $3.26 billion mission.


Launch: October 15, 1997 on a Titan IVB/Centaur rocket from Cape Canaveral, Florida

Flybys of Venus: April 26, 1998, 176 miles (234 km) and June 24, 1999, 370 miles (600 km)

Flight over the Earth: August 18, 1999, 727 miles (1,170 km)

Flyby of Jupiter: December 30, 2000, 6 million miles (10 million km)

Arrival of Saturn: July 1, 2004 (June 30 in California)

Giovanni Domenico Cassini (1625-1712) was an engineer, mathematician and astronomer of Italian origin and naturalized French. He first identified a gap (the eponymous Cassini Division) between two of Saturn’s most prominent rings. Cassini also discovered four of Saturn’s moons, including the odd two-tone Iapetus.

Cassini’s name adorned the mission’s 22-foot-long (6.8-meter) NASA-built orbiter. The Cassini orbiter would ultimately circle Saturn 294 times between its arrival on the gas giant in July 2004 (June 30 according to clocks at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.) and its grand finale in September 2017. Cassini has traveled the planet in unrivaled conditions. detail using a dozen instruments, from visible, ultraviolet and infrared sensors to radiometers, spectrometers, magnetometers and a powerful radar imager.

Dutch physicist, astronomer, and mathematician Christiaan Huygens (1629-1695) was the namesake of a 9-foot-wide (2.7-meter) disc-shaped probe. The Huygens probe was built by the European Space Agency and designed to be dropped into the thick hydrocarbon soup atmosphere that covers Saturn’s largest moon, planet-sized Titan. (Titan is larger than Mercury and nearly the size of Mars.) After parachuting through Titan’s smog clouds in January 2005, the Huygens probe and its suite of six instruments landed triumphantly on a rocky surface never before seen by mankind, under a brilliant orange sky.

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