Cassini: The Grand Finale

Cassini: The Grand Finale


After 13yrs in orbit around Saturn, the international Cassini-Huygens mission has begun its final chapter, starting with a series of daring dives between the planet and its rings, and ultimately leading to a dramatic final plunge into Saturn’s atmosphere on the 15th of September 2017.

The manoeuvre put the spacecraft onto its “grand finale” trajectory: a series of 22 orbits each lasting a week, drawing ever closer to Saturn and passing between the planet’s innermost ring and its outer atmosphere. With its repeated dives through this unvisited region the mission will conclude the journey of exploration by collecting unprecedented data to address fundamental questions about the origins of Saturn and its ring system. Launched in 1997 the spacecraft embarked on a 7yr voyage across the solar system, eventually reaching Saturn in July 2004. Several months later the Cassini orbiter released ESA’s Huygens probe which landed on Titan in January 2005, the first landing ever in the outer solar system.

Enshrouded in a thick nitrogendominated atmosphere and partly covered by lakes and rivers, Titan has a weather and hydrological cycle that bears some interesting similarities to planet Earth. However, there are important
differences; the key component there is not water, like our planet, but methane and the temperature is very low at -180C at the surface. Another of Cassini’s breakthroughs was the detection of a towering plume of water vapour and organic material spraying into space from warm fractures near the south pole of Saturn’s icy moon Enceladus.

These salt-rich jets indicate that an underground sea of liquid water is lurking only a few kilometres below the
moon’s icy surface. Recent analysis of data collected during flybys of Enceladus suggests hydrothermal activity could provide a chemical energy source for life, enabling non-photosynthetic biological processes similar to the ones found near hydrothermal vents on Earth’s ocean floor.

Following over a decade of groundbreaking discoveries, Cassini is now approaching its end. With little fuel left to correct its trajectory, it has been decided to end its mission by executing a death plunge into Saturn’s upper atmosphere on Sept 15th, in the process Cassini will burn up, thus satisfying planetary protection requirements to avoid possible contamination of any moons of Saturn that could have conditions suitable for life.

The “grand finale” is not only a spectacular way to complete this extraordinary mission but will also return a bounty of unique scientific data that was not possible to collect during the previous phases of the mission. A near 20yr life in space, over 3billion kilometres travelled, a wealth of scientific data recovered will all be over as Cassini probably the most successful spacecraft ever finally comes to an end in exactly 60 seconds as it enters Saturn’s upper atmosphere at a speed of 123,606kph and vaporizes in a meteorlike fireball.

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