Dr Ian Griffin: Final hours for Saturn's space probe

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September 14, 11 p.m. EDT (8 p.m. PDT, 3 a.m. GMT on September 15, 5 a.m. CEST on September 15): final images expected to begin appearing online in Cassini raw image gallery.

Launched in 1997 with the European Space Agency's (ESA) Huygens probe, Cassini is the first spacecraft to orbit Saturn. That's because scientists have been able to "pursue questions that we never thought Cassini would have the opportunity to answer", he said. "The haze has cleared remarkably as the summer solstice has approached", Cassini Project Scientist Linda Spilker said in a news conference September 13.

Cassini gazed toward the northern hemisphere of Saturn to spy subtle, multi-hued bands in the clouds there. And above all, the Cassini mission helped us better understand the atmosphere and global mechanisms of Saturn itself.

Scientists plan to collect data from the spacecraft's instruments until the very end of the mission. A year on Saturn equals almost 30 Earth years.

Mission scientists and operators are giving Cassini this fiery send-off on objective. Named after the 17th-century Dutch astronomer who discovered Titan, Christiaan Huygens, Huygens was a project of the European Space Agency (ESA) which landed on Titan on January 14, 2005, sending data back to Earth for 90 minutes.


Then, duty dispatched, it accelerated towards Saturn's surface.

"Goodbye, Cassini! Your mission's fini". To mark this occasion we have brought together a selection of the discoveries the mission has made over the years, in a reading list below. "I couldn't ask for more".

On Monday, Cassini began its final orbit around Saturn.

At 1031 GMT, the spacecraft is due to enter Saturn's atmosphere with its antennas pointed toward Earth and its motors running full blast in order to hold its trajectory. "We are going to learn even more over the next day or so".

The spacecraft was named after Giovanni Domenico Cassini, the 17th century Italian-French astronomer. While Voyager was 1970s technology, Cassini is '90s technology. We have new books coming out about Saturn, the rings, the magnetosphere, so many new things Cassini has discovered. Some are spherical, much like our own moon, including Mimas, which, with its large Herschel Crater, resembles the Death Star from "Star Wars". "This shows that a substantial subsurface ocean of liquid water exists beneath the moon's icy crust". He also was the first person to observe Titan. One way scientists explain Saturn's weird infrared glow is through something called "ring rain", where water and ice particles from the rings flow back into the planet and alter its atmosphere composition.


NASA chose to end the mission by safely disposing of the spacecraft, burning it up in Saturn's atmosphere rather than allowing it to run out of fuel and committing its fate to an aimless tumble and potential crash onto one of Saturn's moons.

During the dive there is also a concern that Cassini might impact with ring material - space stuff the size of a grain-of-sand that could damage an instrument or the entire spacecraft.

During its parachute descent the probe captured images of features that looked like shore lines and river systems on Earth.

The Canberra space complex was given the key role of transmitting Cassini's final images of Saturn because the planet will be hovering above Australia on Friday.

But Friday's dive will be like no other. Mission Control will be live on YouTube, Ustream and NASA TV.


Cassini has spent the last two months executing a series of intimate dives through Saturns rings and into its upper atmosphere, collecting invaluable scientific data.

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