To launch itself into its certain death plunge, the spacecraft used the gravity of Saturn’s moon Titan, coming within 120 000 km of the moon on Monday 11 September, to slingshot itself towards Saturn. Since its arrival at Saturn in 2004, the spacecraft has regularly used Titan’s gravity as a means to catapult itself into different positions in order to study the planet and its rings. This ensured that the spacecraft would not have to use its fuel reserves each time it was to make a major course change.
Now the spacecraft’s fuel reservations are almost empty and rather than have Cassini drift aimlessly in the space around Saturn, propel it into deep space (as with the twin Voyager spacecraft) or allow it to crash on Titan or Enceladus, another of Saturn’s moons, scientists at NASA have decided that it must be disposed of properly. Following its use of Titan’s gravity one last time, they have now termed this as the ‘kiss goodbye’.
‘Cassini has been in a long-term relationship with Titan, with a new rendezvous nearly every month for more than a decade,’ said Earl Maize, the Cassini project manager at Nasa''s Jet Propulsion Laboratory in Pasadena, California. ‘This final encounter is something of a bittersweet goodbye, but as it has done throughout the mission, Titan''s gravity is once again sending Cassini where we need it to go.’
Overall the Cassini mission, a collaboration between NASA, the European Space Agency (ESA) and the Italian space agency, has been a phenomenal success, particularly with regards to increasing our understanding of Titan, the second-largest moon in the solar system. In 2005, Cassini put a small robot called Huygens onto Titan’s surface, returning an extraordinary image of rounded pebbles that had been smoothed by flowing liquid methane, which rains down from Titan’s sky and runs into huge seas at northern latitudes. Cassini also recorded images of what scientists believe to be volcanoes that spew an icy slush, as well as vast dunes made from plastic-like sand.
The spacecraft has taken some of the most spectacular images of Saturn and its rings and overall has sent back 453 000 images to Earth.
Will we see it from Earth?
Now avid space aficionados and the Cassini scientific team themselves are hoping that Cassini’s impact into Saturn, at a phenomenal 76 000 miles per hour (just over 122 000 km per hour), will be visible from Earth. It’s expected that Cassini’s collision will cause bursts of light. But it will be hard to see them.
This is because the brightest parts of those bursts will be in ultraviolet - the same wavelength of light that can cause sunburn. Because Earth''s ozone layer soaks up gobs of ultraviolet light, however, any UV flashes will appear dramatically dimmed to anyone watching from the terra firma. Another challenge is that Cassini''s two nexuses of control - NASA and the European Space Agency - won''t ‘see’ the event in the dark of night, making the signal all the much dimmer as western telescopes fight twilight.
To get around this, the Cassini team have asked NASA to use the Hubble Space Telescope to try and capture the exact moment of the spacecraft’s fiery death. Astronomers in the southern hemisphere, such as in Australia, might find themselves in the right place at the right time to record Cassini’s plunge. Finally, there''s a large community of space fans with powerful telescopes and refined techniques sprinkled across the globe that could help.
If you’re interested in finding out more about the Cassini mission, or you’re fascinated to experience the final moments of the spacecraft yourself, the Cassini team have set up a dedicated website
that is counting down to the mission ‘grand finale’.