Cassini spacecraft: And so begins the grand finale to Saturn

26 Apr 2017

An old, but brilliant, image of Saturn taken by Voyager 2 in 1999. Image: NASA/JPL

With a brush past one of Saturn’s many moons, NASA’s Cassini spacecraft is on the home stretch. It only ends one way …

Titan, one of Saturn’s more famous moons, was the staging post for the beginning of the end of one of the most successful space missions to date. A joint mission of NASA, ESA and the Italian Space Agency, Cassini has been orbiting Saturn for years.

Treasure hunt

Cassini has been garnering treasure troves of crucial data on Saturn’s atmosphere, satellites and overall make-up with every package of imagery and telemetry sent back to Earth.

After 13 years of orbiting the giant planet, today (26 April) marks the day when Cassini begins its five-month goodbye.

This farewell will see the spacecraft dive beneath the lowest of Saturn’s many ‘rings’ up to 22 times, collecting information from close to the planet’s surface for the first time ever.

Through these undulating dives, Cassini will, hopefully, gain powerful insights into Saturn’s internal structure and the origins of the rings.

Scientists also hope to obtain the first ever sampling of the planet’s atmosphere and particles coming from the main rings, as well as capture the closest ever views of its clouds and inner rings.

Then, on 15 September, Cassini will plunge one last time towards Saturn, entering its atmosphere and gaining a few final, crucial readings before smashing into the planet’s surface.


Cassini spacecraft

The spacecraft made its 127th and final close approach to Titan on 21 April, passing at an altitude of about 979km above the moon’s surface.

“Cassini’s up-close exploration of Titan is now behind us, but the rich volume of data the spacecraft has collected will fuel scientific study for decades to come,” said Linda Spilker, the mission’s project scientist.

Her colleague Earl Maize added that following this flyby, the team is committed to the finale.

“The spacecraft is now on a ballistic path, so that even if we were to forgo future small course adjustments using thrusters, we would still enter Saturn’s atmosphere on 15 September, no matter what.”

Given the significance of today’s date, Google is celebrating the grand finale, with an alternative Doodle (not used) below it.

Last month, Cassini’s fascinating mission around Saturn contained a big surprise, revealing that Pan, one of the giant planet’s moons, took a peculiar shape: ravioli.

Image: NASA/JPL-Caltech/Space Science Institute

Image: NASA/JPL-Caltech/Space Science Institute

The exact origin of the rings of Saturn has perplexed astronomers for centuries but, using the latest technology, the pieces of the puzzle are gradually being put together by researchers unattached to the Cassini mission.

A team from Japan analysed mid-infrared images taken by the Subaru Telescope in 2008 – the highest-resolution ground-based views ever made – to unlock new secrets behind what makes the rings tick.

Saturn rings

A three-colour composite of the mid-infrared images of Saturn on 23 January 2008 captured with COMICS on the Subaru Telescope. Colour differences reflect the temperatures; the warmer part is blue, the cooler part is red. Image: NAOJ

Gordon Hunt was a journalist with Silicon Republic