One of the best things about mankind is he never ceases to be curious. And, in his quest to explore more and more of the universe, he is constantly bombarded with new discoveries.
A wave of sadness washed over the Cassini team as the mission came to an inevitable end. But, the decade-long journey of new discoveries by Cassini leaves behind a whole new set of questions that await answers.
NASA and ESA joint forces to send Cassini to the second largest planet in our solar system, Saturn. Pioneer 1 and Voyager had already sent back information regarding Saturn and its moons during their flybys. But this would be the first time in space travel that a spacecraft would be landing on Titan. The seven-year-long journey began in 1997 with two Venus flybys and one Earth and Jupiter flybys to give Cassini the boost to reach its destination, Saturn.
Methone and Pallene
The very first discovery by Cassini was two more natural satellites locked in Saturn’s gravity. Methone and Pallene are said to have no visible craters and are quite an egg-shaped due to the tidal forces of their host planet. Nothing very surprising, is it?
The world of Enceladus
It was during the close flybys near Enceladus that had the team scratching their heads. Its complex terrain revealed temperatures more than predicted. Moreover, traces of carbon dioxide, carbon monoxide and ammonia were discovered when Cassini performed its closest flyby of 16 miles above the surface. This allowed it to sample particles and gases like never before. Analysis of these samples showed that few of the particles had ventured in from outer space. Their speed and direction were not the same as Saturn’s native dust particles.
It’s continuous monitoring also revealed earth like tectonics on Enceladus, with a slight twist. The plates seem to be moving only in one direction, unlike our planet, where they go haphazardly. Over time, it saw numerous tiger stripes in the south polar region from which the icy particles forming the geysers are supposed to originate. The large cloud of water vapour, traces of ammonia and sodium salts and geysers, all point in one direction: there has to be liquid water on Enceladus!
What does Titan say?
Cassini-Huygens marked itself in history when it landed on Titan, farthest and the only landing so far in the outer solar system. In its duration of two hours and twenty-seven minutes, it revealed Earth-like meteorology in Titan’s world. Both our planet and Titan have nitrogen-dominated atmospheres and the mission simply confirmed this fact. The hydrocarbon lakes and seas that were predicted brought a surprise, though. Saturn’s distance from the Sun is too far for the gases like methane and ethane to live in gaseous form. These are present in the form of lakes. However, out of the 620,000 miles of the surface covered by Cassini, two percent was in the liquid state. Moreover, all these seas were found to be in north pole.
Discovered by Giovanni Cassini, Iapetus is the third largest satellite of Saturn. It is one of a kind. The Ying Yang kind. Its peculiar two-tone colouration came to light when Giovanni tried to spot it in the eastern hemisphere. After all, a body orbiting a host should eventually appear in both the hemispheres. He failed. For a second time, after the western hemisphere, he waited for it to appear on the eastern side. When it didn’t, he used better telescopes to discover that the other side was two magnitudes darker. It was then determined that Iapetus is tidally locked to Saturn. Cassini mission revealed large impact basins, supporting the theory that the moon has long-runout landslides.
So far, the sun had shone on the southern hemispheres on Saturn. During Equinox, when sun rays are directly projected upon the equator as it moves towards the northern hemispheres, Cassini studied the seasonal changes on Saturn and its interactions with its moons and moonlets.
The Monster Storm
NASA had never seen something like it. It was all over the northern hemisphere of the planet, slowly circling around it. Such huge storm was occurring after two decades and scientists wondered what could be happening on Saturn for such a strong storm to take place. And then, something even more astonishing happened. When it met its tail, after completing a complete circle around Saturn, it died! No one knows why it happened the way it did. It is the first time a storm had choked upon itself.
During its mission, Cassini sent back 453000 images and travelled 4.9 billion miles before eventually plunging into Saturn to allow life on Enceladus to flourish. It vaporized shortly after entering Saturn’s atmosphere, leaving the crew with surprisingly new places to look for potential life.