Farewell to Cassini

Artist’s impression of Cassini burning up in Saturn’s upper atmosphere. Credit: NASA/JPL-CALTECH

Since its arrival in 2004, over a period of 13 years, Cassini has captured about 450,000 spectacular images of the Saturn system, enabling us to have unprecedented views of “lord of the rings” some of which are now images of space exploration. The spacecraft was launched on October 15, 1997, aboard a Titan 4B Centaur rocket from the Cape Canaveral Air Force Base in Florida on a seven-year journey to ringed planet, achieving orbit insertion on July 1, 2004.

Artist’s impression of Cassini in orbit around Saturn. Credit: NASA/JPL/Space Science Institute

Because of planetary protection, Cassini must die, it’s not hard for a microscopic creatures hitching a ride into space. After its 22 so-called ‘grand finale’ orbits, on September 15 at 4:37 a.m. PDT (ERT) or 11:37 Greenwich Mean Time, that is 12:37 local time in Spain or 21:37 Australian Eastern Standard Time, we will lose the signal to Cassini for it would be on the could tops of Saturn, around 1510 kilometres above them, ready to be destroyed, making its entry at 120,000 kilometres per hour. It would be the end to a historic mission which has provided enough data to fill more than 4000 scientific papers.

Cassini gives us this true-colour view of the largest, most intense storm observed on Saturn. Credit: NASA/JPL-Caltech/Space Science Institute

The last 22 orbits ventured into a previously completely unexplored region of Saturn, providing unprecedented observations of the planet’s rings and its magnetic and gravitational fields. This showed scientists that Saturn’s rings have less mass than expected, which suggests they’re far younger than previously thought, perhaps just 100 million years old, they could be the result of a moonlet being ripped apart by Saturn’s gravity, or a collision between moonlets, this means that we are seeing Saturn at a unique time in Saturn’s evolution.

Rising abruptly from the edge of Saturn's B ring are vertical structures casting long shadows on the ring in this image. Credit: NASA/JPL-Caltech/Space Science Institute

With Cassini was travelling the European Space Agency Huygens lander to explore Saturn’s biggest moon, Titan, which was deployed on December 25, 2004 and landing on the surface of the alien moon on January 14, 2005, making it the first landing on a world in the outer solar system. There it was found that is rains, with Earth the only other place on the solar system that this happens and also it found liquid-methane lakes. Recent observations have also discovered complex pre-biotic chemicals form in Titan’s atmosphere falling down on to its surface. 

Natural-colour image of Titan's upper atmosphere. Credit: NASA/JPL/Space Science Institute

Many were the achievements and discoveries of the Cassini mission, such finding out about the buried liquid-water ocean on the moon Enceladus that escapes to the surface via geysers. Scientists suspect this underground sea might be capable of hosting alien life. Cassini also uncovered mountainous waves of rubble and “moonlets” in Saturn's rings and an effect that turns its atmosphere blue in the winter.

Ligeia Mare, shown here in a false-colour Cassini image, is the second largest known body of liquid on Saturn's moon, Titan. Credit: NASA/JPL-Caltech/ASI/Cornell

If life is ever found on Mars, one could argue that it could be the result of meteorite contamination from Earth, since the red planet and ours have constantly swapped rocks over the 4.6-billion-year history of the solar system. But if life if present on a frigid faraway place such any of the moons of Saturn, then perhaps life is a constant on the Universe, the Cassini mission has told us to be more opened mind to the range of possibilities on where life could thrive, leaving open question to solve, so we need to go back to the outer planets and explore further this possibility. No doubt that Cassini will be missed, but it is time to explore more, Farewell to Cassini.

Cassini's view of the water-jet coming out from Enceladus. Credit: NASA/JPL-Caltech/Space Science Institute 

Sources: Cosmos Magazine, Scientific American, NASA