It sounds like a scene from a disaster movie: speeding along at 113,000 km/h, a $1.5 bn vehicle the size of a bus falls into a foggy abyss.
After studying Saturn for almost twenty years, Cassini’s mission ended in dramatic style, finishing what many claim to be the most successful exploratory space mission in history. Let’s look at some of the amazing discoveries it made.
Cassini’s most dazzling legacy is the collection of 400,000 photos it took during its mission. While each picture contains scientific treasures, many of its eye-catching shots – including surrealistic perspectives of the ring system, stark images of light and shadow, and serene shots of various moons – were taken solely for aesthetic reasons., An example of this was seen with Saturn’s deep forming atmospheric clouds During almost half of Saturn’s seasonal cycle, Cassini snapped photos of wavelike patterns, little swirls, and even a giant storm system.
Even more exciting was Cassini’s step-by-step exploration of the surface of Titan. The massive moon is covered in smog, but infrared cameras and radar instruments managed to image and map shifting sand dunes, ice volcanoes, mountain ranges and even patchy networks of lakes. The European Huygens probe that hitched a ride with Cassini soft-landed on Titan in January 2005. This provided valuable data about the moon’s surface. It found that Titan is a frosty and swampy environment, rich in organic compounds. It is battered by massive storms of methane rain and littered with pebbles and boulders of frozen water. In other words, Titan is a sci-fi writer’s paradise.
There are plenty of further interesting examples from other moons like Hyperion, Pan and Mimas. But these can’t compete with Enceladus. From cracks near its south pole to geysers that spewed dust, water vapour and ice crystals into space – the moon is a feast for the eyes… With all the heat and water on the moon, scientists have started to question what organisms may flourish underneath the surface.
It is one of many puzzles that the Cassini team have been trying to understand. Saturn’s rings. Early signs suggest that the rings are only 100 million years old. Despite measuring around 273,000 km across, the average thickness of the rings is only 20 m. Gravitational interactions with embedded moonlets create thin gaps, tightly-wound spiral waves, propeller-shaped disturbances, clumps and kinks, and even vertical ‘walls’ of uplifted ring material, casting dramatic shadows during Saturn’s equinox.
Since April, the intrepid spacecraft had been performing a series of staggering dives through the 2,000 km-wide opening between the planet’s cloud tops and the inner edge of the rings. By accurately tracking Cassini’s path, researchers were able to ‘weigh’ the rings for the first time. The bold dive manoeuvres also produced the most detailed views of Saturn’s atmosphere, its tiny inner moons, and, obviously, of the rings themselves.
Destroying Cassini to avoid its collision with Enceladus – one of the most promising environments in the Solar System was crucial. This prevented contamination of its subsurface ocean, keeping scientists’ expectations high on a final discovery – extra-terrestrial life.