The Cassini mission ends this week as the spacecraft makes a final rendezvous with Saturn's moon Titan.
Spacecraft Cassini has made several significant contributions to what we know about space and other planets in the solar system. Cassini made several flybys around a few planets, discovered seven of Saturn's moons, and discovered that the moon Enceladus had an atmosphere, among many other accomplishments. Many of these accomplishments occurred around Saturn and its satellites, where Cassini spent 13 years of its mission. The mission was launched on October 15, 1997, and is set to end on Friday, September 15, 2017.
The spacecraft will end its mission by taking a death plunge into Saturn's atmosphere. It will be destroyed as it descends, and its components will melt and disperse with Saturn's gases. Cassini's destruction is, unfortunately, necessary. Its destruction will ensure that the planet's moons, a number of which may be habitable, will not experience biological contamination.
Cassini captures the moon Io as it passes in front of Jupiter. [Image by NASA/JPL/University of Arizona]
Cassini set its irreversible collision course with Saturn as it performed a flyby around the moon Titan on September 11. Titan is Saturn's biggest moon, and it's quite special. It's larger than Mercury, has a dense atmosphere, and has evidence of stable liquid bodies on its surface. However, it's also particularly special to the Cassini mission. The spacecraft has been using Titan's gravity as a kind of slingshot to aid its journeys around Saturn. Without Titan's help, Cassini would have had to turn on its propulsion system and use up fuel whenever it had to make a significant maneuver. As a result, its mission would have ended sooner.
The flyby around Titan this past Monday was basically a “goodbye kiss”. "Cassini has been in a long-term relationship with Titan, with a new rendezvous nearly every month for more than a decade," said Cassini project manager Earl Maize. Maize describes this final flyby as a bittersweet goodbye, as Titan has been instrumental during Cassini's excursions around Saturn. According to Maize, “Titan's gravity is once again sending Cassini where we need it to go."
In total, Cassini has orbited Titan 127 times. It's last rendezvous with Titan is also productive, as the spacecraft managed to gather images and data that it sent to Earth on September 12.
Artist's impression of Titan and Cassini [Image by NASA/JPL-Caltech]
Titan was also the site of many of Cassini's greatest achievements. In 2005, Cassini placed a robot called Huygens on the surface of Titan. Together, Cassini and Huygens managed to glean important data about the Saturnine moon.
As of now, the spacecraft is running quite low on fuel. According to Cassini scientist Michelle Dougherty, the Cassini mission is determined to make the most of the time that the spacecraft has left. Scientists want the spacecraft to take more images of the moon Enceladus as well as Saturn's rings. About three hours before Cassini dives into Saturn, the spacecraft will send all its data to Earth.
Cassini's final goodbye will be bittersweet indeed. "The Cassini mission has taught us so very much,” says Cassini programme scientist Curt Niebur, “and to me personally I find great comfort from the fact that Cassini will continue teaching us right up to the very last seconds."
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