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Cassini’s penultimate orbit: 1st images

Cassini spacecraft at Saturn now in its final year. Carolyn Porco said: “Let these images … remind you that we’ve lived a bold and daring adventure around the solar system’s most magnificent planet.”

This view from NASA's Cassini spacecraft was obtained about half a day before its first close pass by the outer edges of Saturn's main rings during its penultimate mission phase. Read more about this image from NASA/JPL-Caltech/Space Science Institute

Cassini acquired this view over Saturn’s turbulent north pole and hexagon, about half a day before its first close pass by the outer edges of Saturn’s main rings during its penultimate mission phase. Read more about this image from NASA/JPL-Caltech/Space Science Institute.

NASA’s Cassini spacecraft – in orbit around Saturn since 2004 – will finish its mission with a grand finale in 2017. Mission controllers have put the spacecraft into a new orbit – its penultimate, or second-to-last orbit – called a Ring-Grazing Orbit on November 30, 2016. On December 2 and 3, 2016, the craft obtained its first views of Saturn’s atmosphere since beginning this latest mission phase. The new images let you peer down at Saturn’s north pole, glimpsing its atmosphere and rings from up close, with a good look at the planet’s strange, northern polar hexagon.

Cassini imaging team leader Carolyn Porco at Space Science Institute, Boulder, Colorado said:

This is it, the beginning of the end of our historic exploration of Saturn. Let these images — and those to come — remind you that we’ve lived a bold and daring adventure around the solar system’s most magnificent planet.

Cassini’s imaging cameras acquired these latest views about two days before the spacecraft’s first ring-grazing approach to the planet.

This graphic shows the closest approaches of Cassini's final two orbital phases. Ring-grazing orbits are shown in gray (at left); Grand Finale orbits are shown in blue. The orange line shows the spacecraft's Sept. 2017 final plunge into Saturn. Read more about this image from NASA/JPL-Caltech

This graphic shows the closest approaches of Cassini’s final two orbital phases. Ring-grazing orbits are shown in gray (at left); Grand Finale orbits are shown in blue. The orange line shows the spacecraft’s September 2017 final plunge into Saturn. Read more about this image from NASA/JPL-Caltech

Each new orbit around Saturn lasts about a week. There will be 20 orbits in this configuration, which carries the spacecraft high above Saturn’s northern hemisphere before sending it skimming past the outer edges of the planet’s main rings. Future passes will include images from near closest approach, including some of the closest-ever views of the outer rings and small moons that orbit there.

The next pass by the rings’ outer edges is planned for December 11. The ring-grazing orbits will continue until April 22, when the last close flyby of Saturn’s moon Titan will once again reshape Cassini’s flight path. With that encounter, Cassini will begin its Grand Finale, leaping over the rings and making the first of 22 plunges through the 1,500-mile-wide (2,400-kilometer) gap between Saturn and its innermost ring on April 26.

On September 15, 2017 the mission’s planned conclusion will be a final dive into Saturn’s atmosphere.

During its plunge, Cassini will transmit data about the atmosphere’s composition until its signal is lost.

See more images: Cassini mission to Saturn Hall of Fame

Saturn hexagon, as seen by the Cassini spacecraft on December 2, 2016. Read more about this image.

This collage of images from Cassini shows Saturn’s north pole, its famous hexagon and a portion of the rings as viewed with four different spectral filters. Each filter is sensitive to different wavelengths of light and reveals clouds and hazes at different altitudes. Image acquired December 2, 2016. Read more about this image from NASA/JPL-Caltech/Space Science Institute.

Bottom line: NASA’s Cassini spacecraft – which has been orbiting Saturn since 2004 – is nearing its grand finale in 2017. A new orbit in preparation for the end of the mission shows scenes from high above Saturn’s northern hemisphere, including the planet’s intriguing hexagonal jet stream.

Deborah Byrd

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