Published: Fri, September 15, 2017
Science | By Boyd Webster

Nine of Cassini's most exciting discoveries about Saturn

Nine of Cassini's most exciting discoveries about Saturn

After 13 years orbiting the giant ringed planet and exploring its moons, the unmanned, nuclear-powered probe will be incinerated at 7:55 am EDT (4:55 am PDT) on September 15 in a planned maneuver that will see it plunge into Saturn's upper atmosphere. The finale is significant because Cassini was the only spacecraft out of four to enter Saturn's orbit.

The Canberra station has been with Cassini through every step of its journey of discovery, from when it first opened its "eyes" to the Universe after launching in 1997 to receiving the signal confirming that Cassini had arrived safely in orbit at Saturn in 2004. The site provides an up-to-the-second countdown of the final dive and the current distance between Cassini as the planet itself.

To study Saturn and its moons up close. Researchers think they may have gotten that way by being ground up, but are not sure what process might have made that happen, project scientist Linda Spilker said in an interview with CNBC.

"That will enable sampling instruments, particularly the ion and neutral mass spectrometer, to get data as deep into the atmosphere as Cassini will permit it", he said. There are some huge gaps in the rings where the atmosphere is silent and less dusty.

With INMS leading, Cassini will pierce Saturn's atmosphere, an area the spacecraft wasn't originally created to explore.

As per the reports of NASA, "The mission's final calculations predict loss of contact with the Cassini spacecraft will take place on September 15 at 7:55 a.m. EDT (4:55 a.m. PDT)". Eastern Time for the spacecraft, but given the time it takes for the signal to reach Earth, we will receive those last bits of data just before 8 a.m. - long after Cassini is "gone". "It will radiate across the solar system for almost an hour and a half after Cassini itself has gone", Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, Cal., said in a news release.

Mission scientists and operators are giving Cassini this fiery send-off on objective.

Scientists were especially interested in Saturn's giant moon Titan, which has a nitrogen and methane atmosphere and in some ways resembles an early version of Earth.

These will include views of the moons Enceladus and Titan, which harbour huge volumes of liquid water beneath their icy surfaces and where scientists believe simple lifeforms might be able to eke out an existence. Cassini was the NASA-developed Saturn orbiter, and Huygens was the European-built probe that sat on-board, which would eventually descend on to the surface of Saturn's biggest moon, Titan.

For more than a decade, NASA's Cassini spacecraft at Saturn took "a magnifying glass" to the enchanting planet, its moons and rings.

Cassini has made 20 of these sub-ring orbits, using the last five to dip so close to Saturn that it could directly measure the planet's atmosphere.

On the eve of its final descent, other instruments will make detailed observations of Saturn's aurora borealis, temperatures and polar storms.

But beyond concerns about interrupting the lives of microbes, NASA and other space agencies try to take a "leave no trace" approach to space exploration when they can, opting for controlled crashes into planetary bodies when they have to park a spacecraft somewhere after a (hopefully) long mission. Why is the program ending now after 13 years?

But as with all things involving spaceflight, the reason for Cassini's collision course with Saturn is nothing if not practical.

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