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Adapted from an article by Kenneth Chang published in The New York Times, September 14, 2017:

NASA’s Cassini spacecraft, the intrepid robotic explorer of Saturn’s magnificent beauty, has finally ended its 20-year journey. By design, the probe vanished into Saturn’s atmosphere, disintegrating moments after its final signal slipped away into the background noise of the Solar System. Until the end, new measurements streamed one billion miles back to Earth, preceded by the spacecraft’s last picture show of dazzling sights from around the Sun’s sixth planet.

15cassini-beforeplunge-jumbo

Credit: Credit NASA/JPL-Caltech/Space Science Institute

 

The mission for Cassini, in orbit since 2004, stretched far beyond the original four-year plan, sending back multitudes of striking photographs, solving some mysteries and upending prevailing notions about the Solar System with completely unexpected discoveries.

Even at the end, 20 years after launch, Cassini and its instruments remained in good working shape. The plutonium power source was still generating electricity. But there was not enough propellant fuel left to safely send Cassini anywhere except into Saturn.

In the very last phase of the mission, Cassini dove through the gap between Saturn and the planet’s innermost ring. This provided new, sharp views of the rings and allowed the craft to probe the planet’s interior, as another NASA’s Juno spacecraft is doing at Jupiter.

Links: read the full article; also NYT’s ‘100 Images from Cassini’ feature.

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In this NY Times slideshow, Kenneth Chang curates a selection of images from NASA’s Cassini spacecraft’s farewell tour. Cassini entered orbit around Saturn 11 years ago; last fall, the space agency granted a final extension, through 2017, when the spacecraft will have exhausted the fuel for its thrusters. On August 17, it made its last flyby of Dione, the fourth largest of Saturn’s more than 60 moons, at 700 miles wide. Dione has its own mysteries that planetary scientists hope to unravel.

See the slideshow here (external link).

From APOD, June 3, 2105:

A new view of Saturn’s moon Hyperion was released by the Cassini team during a recent fly-by.

hyperion02_cassini_1024

Credit: NASA/JPL-Caltech/SSI

The images shows numerous unusually-shaped craters with dark material at the bottom. At around 250 km across, its gravitational pull on Cassini reveals that it is mostly empty space. The unusual crater shapes are thought to arise from surface impacts, which compress and eject surface material, unlike the regular circular shock-wave craters seen on other moons and planets.

Link: APOD, June 3, 2015.

This spring, NASA officials will conduct a review of the spacecraft that have outlived their original missions. For the 2015 fiscal year, which begins October 1, the agency faces particularly tough choices, in order to balance their books.

A decade after swinging into orbit around Saturn, the venerable Cassini spacecraft is still working, well beyond the four years of science the space agency had hoped to get. But the spacecraft is running low on maneuvering fuel, and its managers want to end with a scientific bang – an ambitious agenda that includes 22 orbits through a gap between the planet and its innermost ring before sending the craft on a death plunge into Saturn in 2017. For several months, however, scientists have worried that NASA, financially squeezed like the rest of the federal government, could terminate the mission sooner.

Credit: NASA/JPL/Space Science Institute

The Mars rover Curiosity, which will cost $68 million this year to operate, will complete its two-year primary mission in June 2014, so money for continued roving will come out of funds dedicated to “extended missions.” For this year, that amount is $140 million, which includes $58 million for Cassini. Other extended missions include the Messenger spacecraft at Mercury, the Mars rover Opportunity, and the Mars Reconnaissance Orbiter.

No one expects NASA to turn off Curiosity, which will not even arrive at its primary science destination until later this year, raising concerns that Cassini may be on the chopping block. More recently, NASA planetary science director James Green told scientists that the perception of Cassini versus Curiosity was inaccurate and that officials could instead scale back the cost and scope of the extended missions. The agency could also juggle other money to pay for both Cassini and Curiosity, but that could have consequences like delaying future missions, which themselves are under pressure to deliver the maximum scientific benefits for a smaller cost.

Links and source: NY Times op-ed by Kenneth Chang.

On July 19, 2013, NASA’s Cassini orbiter passed into Saturn’s shadow and turned toward the Sun, capturing an image of the planet’s night side and the backlit semi-transparent rings. Cassini also captured seven of the moons and three planets. This was the third time our home planet was imaged from the outer Solar System; the second time it was imaged by Cassini from Saturn’s orbit; and it was the first time ever that inhabitants of Earth were made aware in advance that their photo would be taken from such a great distance.

Credit: NASA/JPL/SSI

Credit: NASA/JPL/SSI

In this video posted on her blog, Emily Lakdawalla of the Planetary Society talks us through some of the hidden features of this spectacular mosaic.

Credit: Emily Lakdawalla (via YouTube)

A newly released image of Titan, Saturn’s largest moon reveals details of seas or lakes near its northern pole.

Credit: NASA/JPL-Caltech/U. Arizona/U. Idaho

The false-color mosaic, made from infrared data collected by NASA’s Cassini spacecraft, reveals the differences in the composition of surface materials around these hydrocarbon lakes. Titan is the only other place in the Solar System that we know has stable liquid on its surface – but its lakes are made of liquid ethane and methane rather than liquid water. While there is one large lake and a few smaller ones near Titan’s south pole, almost all of Titan’s lakes appear near the moon’s north pole.

The image data suggest parts of Titan’s lakes and seas may have evaporated and left behind the Titan equivalent of Earth’s salt flats. They appear orange in this image against the greenish backdrop of Titan’s typical bedrock of water ice.

Launched in 1997, Cassini has been exploring the Saturn system since 2004. A full Saturn year is 30 years, and Cassini has been able to observe nearly a third of a Saturn year. In that time, Saturn and its moons have seen the seasons change from northern winter to northern summer.
Links: press release from Cassini imaging team; annotated image from NASA’s Cassini mission homepage.

On July 19, 2013, NASA’s Cassini spacecraft captured color images of Earth and the Moon from its perch in the Saturn system nearly 900 million miles (1.5 billion kilometers) away.  Earth and the Moon appear as mere specks – Earth a ‘pale blue dot’ and the Moon a stark white, visible between Saturn’s rings. It was the first time Cassini’s highest-resolution camera captured Earth and its moon as two distinct objects.

IDL TIFF file

Credit: NASA/JPL-Caltech/Space Science Institute

The MESSENGER probe, orbiting Mercury, also snapped pictures of our home planet. Full details and further images may be found in this JPL press release.