Cassini makes its dramatic exit

15 September.  At around 11:30 this morning the Cassini spacecraft sent its final signal to Earth as it plunged into the thick atmosphere of the planet Saturn, bringing to an end its 20-year voyage of discovery, a voyage that has provided scientists with a wealth of data about the ringed planet and its moons, and some of the most thought-provoking images ever captured.

For Queen Mary’s Prof. Carl Murray it was something of a sad moment as it marked the end of a career-long association with the spacecraft. Carl has been a member of the Cassini camera team since 1990 and is one of the scientists who have been privileged to work on the data sent back by the spacecraft since it was launched in 1997. Like many, Carl has come to see Cassini as a constant companion, probing distant worlds where humans cannot (yet) venture.

Carl was at Caltech in the USA for Cassini’s final moments, along with many other scientists who had played a part in this remarkable mission — and a very large press and media presence.

In its last few months of operation, Cassini embarked on a daredevil rollercoaster ride, swooping through Saturn’s famous rings several times. Despite the risk of collision, Cassini survived this final stage of its mission and has sent back some remarkable pictures of the icy lumps that make up the ring system. Among the last few pictures it took was one of “Peggy”, a particularly interesting ring object that Carl discovered in 2013 in photos taken by Cassini and nicknamed for his mother-in-law as it was on her birthday that he found it.

After 20 years in space, Cassini was nearing the end of its fuel reserves and the decision was taken to deliberately fly it into Saturn, rather than risk its crashing into one of the moons and contaminating it. The moons of Saturn have been revealed by Cassini as likely places where conditions might just be suitable for some kind of life to have evolved, so it is vital that we do not introduce Earthly contamination in our efforts to study them.

Carl Murray can be seen and heard talking about the mission on the BBC: Sky at Night on 10 September; Inside Science on 14 September and Horizon on 18 September.

Image credit: NASA / JPL-Caltech