One of the most beloved planetary science missions of NASA gave some extraordinary insights about the ringed planet.

Cassini spacecraft was launched on 15^th October 1997 with the intentions of exploring the Saturn and its rings. It explored the Saturnian system for 13 years before the mission was ended by sending Cassini into the upper atmosphere of this gas giant, which destroyed the spacecraft. It ensured that potentially habitable moons in this system will not be contaminated by any terrestrial microbes on the spacecraft. Having said that, even the death of one of the most beloved planetary missions of NASA provided us with some incredible information.

In its dying moments, Cassini was pushed into a daring set of orbits during which the spacecraft threaded itself between Saturn and its rings. The name assigned to this mission was ‘Grand Finale’. Contrary to what we see from distance, there is nothing peaceful and calm in there. Scientists found exactly what is happening between the upper atmosphere of Saturn and its innermost ring. The papers published on the 4^th of October described the eye-catching phenomena. The images captured by Cassini showed a pounding hail of compounds smashing into the equatorial region of Saturn. In addition to that, researchers found an electric current which was generated solely by the magnetic field and winds of the planet. Linda Spilker, the Project Scientists for the Cassini Mission at NASA, said,

“We really did think of it as a gap but the operation ended up producing a much richer science return than we had imagined.”

The fact that neither Cassini nor its instruments were supposed to go that deep into the Saturnian system, it is an incredible achievement for this spacecraft. Even the scientists behind this mission were not confident that the spacecraft will be able to survive long enough to initiate Grand Finale. The researching team mentioned that despite the end of the mission, there is a lot more to reveal from the data gathered by Cassini. Spilker elaborated that in the following words:

“You look at basically the firehose of data that’s come back from Cassini in the past 13 years, really, we’ve only skimmed the cream across the top of the data set. The next step that’s happening even now is to take those pieces and put them together into a coherent picture to look across all of the data sets and ask is there one common story.”

However, scientists have certainly extracted some useful information about the ringed planet and that is amazing in itself. One of these discoveries was simply shocking for the scientists on the team. The Ion and Neutral Mass Spectrometer (INMS), which can detect the chemical composition of the material it catches, found something least expected.

According to the estimates of the researchers, the ‘Ring Rain’ (trickle of tiny particles falling from Saturn’s innermost ring towards the upper atmosphere of the planet) should have some Hydrogen and mostly Helium but findings showed a lot more than these compounds. INMS detected traces of Methane, Carbon Monoxide, and Nitrogen in that rain. In addition to that, some unidentifiable remains of organic molecules were also there. Bonnie Meinke, a Saturn Scientist at the Space Telescope Science Institute who was not a part of this research, commented about that by saying,

“Since the end of the mission, there’s been a lot of talk about these INMS results. At first glance, it’s the kind of thing that you almost don’t believe, and as a scientist, you have to do a little gut check.”

Similarly, some other instruments of the Cassini spacecraft indicated the presence of water ice and silicate particles in this ring rain. They also suggested that this downpour is initiated when these particles interact with the highest levels of Saturn’s atmosphere. Statistically speaking, all this adds up to 9,000 kg/sec around the whole ring structure. This gives birth to a new mystery: From where does all this material come from? Meinke proposed a possible solution to that in the following words:

“This can’t be a continuous process, or the rings wouldn’t be there. The real story that [the paper is] telling is about the churn of Saturn’s rings … rings can be long-lived because they’re constantly moving and turning over.”

You can have a look at Cassini’s amazing work: