In 2004, the Cassini spacecraft began the first in-depth study of the planet Saturn. The vessel is equipped with 12 instruments, which have been designed to collect data about several areas of the planet: including its moons, rings, environment and magnetosphere. The knowledge that the spacecraft has uncovered is so extensive that the mission has been extended twice. The final mission, a seven year period called Cassini Solstice Mission, will end with ‘The Grand Finale.’ This event is scheduled to incorporate 22 deep dives between the planet’s clouds and innermost ring, ending with a massive plunge directly into its atmosphere.
Cassini has unveiled a significant amount of information about the planet’s system, it many moons and the rings which surround it. Its largest moon, Titan, has shown many features which scientists believe are similar to those that would have appeared on our planet, before life on Earth evolved. These include: lakes, rivers, dunes and possibly volcanoes. Another moon, Enceladus, has also yielded unexpected observations. This moon has a spray of icy particles that form a towering plume from its surface, which is three times its diameter. These geyser-like jets spew water vapor and ice particles into Saturn’s most expansive ring, the E ring, at an average of 800 miles per hour from an underground ocean beneath the moon’s icy crust. Measurements taken by the vessel, show the water body to be approximately 6 miles deep under an icy shell between 19 and 25 miles thick.
Coming as close as 15 miles to the moon, Cassini has unearthed that the fresh coating on it, and the icy particles fed into the E ring, originate from vents which are connected to a global subsurface saltwater ocean. The E ring is made mostly of ice droplets, but contains peculiar nanoparticles which Cassini detected. These can only be generated where liquid water and rock interact at temperatures greater than 90 degrees Celsius. This had led scientists to speculate that there may be hydrothermal vents beneath Enceladus’ icy shell, similar to those that can be found on Earth’s ocean floor. The information that Cassini has sent back to Earth, also revealed molecular hydrogen and carbon dioxide to be present. These factors are essential for methanogenesis, a process which sustains tiny life forms in dark underwater environments, to take place.
The plume venting from Enceladus’ south pole, the hydrocarbons within the plume, and a salty ocean with hydrothermal vents all point to a habitable surface and the possibility of locating life beyond Earth’s atmosphere. The three necessities for sustaining life: water, organic molecules, and an energy source have been found on Enceladus. This discovery is believed to be one of the most scientifically interesting finds about our Solar System to date and, as more information is collected from Cassini, there may be additional evidence that will help to prove the theory.