Cassini spacecraft to end its mission on Friday

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this is an excellent link for the story of Cassini

Cassini Saturn Probe Survives 1st 'Grand Finale' Dive

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Cassini’s most impressive feat: Dropping a moon lander on Titan

The spacecraft Cassini will become a streak of ash when it tumbles into Saturn on Friday.

Less than a million miles away, the probe Huygens, which Cassini launched onto Saturn's moon Titan, will be the only evidence of its partner's journey. Huygens is probably in the very spot where Cassini delivered it 12 years ago, settled like a headstone amid moon dust and icy cobblestones.

Cassini and Huygens traveled together from Earth to Saturn's orbit. Their mission represented the symbiotic pairing of NASA and the European Space Agency. NASA's Cassini provided the propulsion. The ESA's Huygens spent eight years and 934 million miles stuck, barnacle-like, to Cassini's much larger belly. On Christmas Eve 2004, Cassini and Huygens split. Huygens landed on Saturn's moon Titan three weeks later.

A dozen years after the separation — and nine years beyond Cassini's expected lifetime — Cassini continued to orbit Saturn. The program was a massive success. Yet Huygens had the most ambitious goal of all: It is the only machine to land on a world beyond the asteroid belt. And, without Huygens, Cassini might never have left Earth's gravity.

Huygens skidded onto Titan on Jan. 14. “Right on time,” Jean-Pierre Lebreton, the French physicist and ESA leader of the Cassini-Huygens mission, told Bloomberg Buisnessweek in 2005. “It was a very emotional moment. It was hard not to cry.”

On its way down, Huygens took the temperature of Titan's atmosphere. It was -150 degrees at 300 miles up, warming to -120 at an altitude of 150 miles, before dropping to -290 at the surface.

The probe also hinted at an answer to one of Titan's curiosities: where the moon got its methane supply. Sunlight destroys methane after a few million years. At 4.5 billion years old, Titan should be tapped out. But Huygens sensed a sharp spike in the amount of methane, jumping by 40 percent on the ground, per the ESA. This suggested that liquid methane exists on Titan, mostly trapped beneath the surface but leaking enough to replenish atmosphere.

The probe gave us “a new view of Titan, which appears to have an extraordinarily Earthlike meteorology, geology and fluvial activity,” wrote the ESA's Lebreton and his co-authors in the journal Nature in 2005.

On the moon, the familiar has a chemically alien twist. The scientists continued: “Instead of liquid water, Titan has liquid methane. Instead of silicate rocks, Titan has frozen water ice. Instead of dirt, Titan has hydrocarbon particles settling out of the atmosphere.” Titan's twist on Earthly features could in theory support microbial life, some chemists say, despite the frigid temperatures.

[Boris13c]

one of the images from Cassini - Saturn and its moon Titan :




Before NASA's Cassini flies into Saturn, take a look back at its best images