Saturn is calling...

There is a great buzz on social media regarding the GRAND FINALE of the highly successful Cassini spacecraft before throwing it on Saturn, in turn destroying it. GRAND FINALE would include its movement very very close to Saturn's ring and that too for 22 times!! 

GRAND FINALE of CASSINI spacecraft includes
22 ring-grazing orbits. (Image:NASA)

It includes trips through 2000 km gap between first ring and the atmosphere of the planet. The spacecraft will move at an astounding speed of 1.2 lakh km/hr (77000 miles/hour) with respect to Saturn. Before its death, It will go where no other spacecraft has ever gone, right in between those rings and by this it will culminate years of dedicated effort by thousands of humans. But why to ' kill' a spacecraft which has improved our understanding of the solar system at a logarithmic scale? Which gave us thousands of images? Inspired us ? Why not leave it orbiting around the Saturn, like moon does around earth? 

It looks cruel to kill it but in reality its not. 

Huygens probe was dropped
by CASSINI on Titan.
(Image:NASA)

Before that we need to pause and comprehend the big picture here. 

The universe is mysterious. It has been the same for thousands of years, since the humans left their cradle of origin in Africa. Across cultures, present and past, we see reverence sometimes fear of the stars, moon, sun and planets. The unknown of the heavenly bodies have mesmerized us for centuries. Now as we move through the 21st century, we are beginning to get the glimpse of their secrets for the first time. The same curiosity which helped us get out of Africa, fuels our desire to explore other worlds. In the last few decades humans have sent huge numbers of space probe to study various planets comets and asteroids of our solar system. Over time tremendous amount of data has increased our knowledge of these worlds. Layering over these initial observations new mysteries continues to arise. Every time a new information pours in from these probes, it stirs the curiosity of even the most placid human. One such mission to explore Saturn and its moons is Cassini-Huygens. 

Lightning storm captured by CASSINI in the
Saturn's atmosphere. (Image:NASA)

The Cassini took 7 years to reach Saturn and that too using gravitational assistance of Venus, Earth and Jupiter. Saturn remains no longer the planet with its rings to adore. Its appreciation goes deep with the Cassini's observations of the lightening storms on Saturn, shining brilliant aurora and its hexagon clouds at the poles. There seem to be no end to fascinating phenomenon on this planet. Biggest among them is the formation of symmetrical hexagon clouds and the rings with width around 10 feet. How can such symmetry and compression be achieved? These questions require immediate re-exploration of the planet with a new spacecraft with much better equipment but hold on!! other observations from Cassini might well force us to go back again.

Fuelled by the unexpected observations on the moons of Saturn the Cassini has filled our bucket of reasons for a future sequel mission. One of the primary objectives of the mission was to drop Huygens probe on Titan to study its atmosphere. All the instruments of Huygens probe were working and communicating with Cassini as it was falling toward the surface of the Titan. The presence of methane in its three forms like water is on earth came as a surprise to scientists. Under the thick fog on the planet lied a landscape of mountains with methane forming huge lakes which was simply stunning.

Water, ice, silica and organic compounds were detected by CASSINI when it passed
through plumes ejected from the surface of Enceladus. (Image:NASA/APOD)

Next began the exploration of second moon, Enceladus. There came the biggest surprise. Huge cracks were observed at the south pole of the moon. Cryo-volcanoes spew ice and water in the form of geysers at the speed of 12200 km/hr into the space and amazingly, some of water vapours were seen leaving the moon reaching far enough to form  E-ring around the Saturn.

To study the content of the geysers in greater detail, the trajectory of the spacecraft was shifted so that it flew right through the ejected plumes. As it passed through, its probes detected salty water ( with sodium chloride), pH similar to that of earth along-with silica sand and ammonia. Most of the spewed content was seen snowing back on the moon but some left its gravitational pull forming a ring around Saturn. One of the most breath-taking observation was the detection of organic molecules like methane, propane, acetaldehyde and propane. The origin of methane on our planet is predominantly of biological origin and its detection in Enceladus opens up the world of extra-terrestrial possibilities. 

In spite of all the discoveries, why are humans killing Cassini?

It is because as the space probe gets old the probability of anything getting awry increases substantially. As the instruments get old they might become unresponsive and loose the proper control of the spacecraft and its trajectory. When the spacecrafts are built, all the possible protocols are followed to prevent any contamination with earth borne microbes but some might slip inadvertently. On our planet we have specialised microbes which are termed extremophiles and those can survive extreme salt, pressure, temperature, heat and space. They are extremely adapted organisms and their independent evolution on these alien moons cannot be denied. One of the reason then to terminate this spacecraft becomes to prevent the moons of Saturn from getting contaminated with the extremophiles stuck on the Cassini. It doesn't matter if the probability of the collision is too low, but its death becomes a blessing in disguise as it opened a possibility of  a gutsier mission.

Bizarre Hexagon clouds, larger than Earth, are a permanent feature
at the north pole of the Saturn. (Image:NASA)

Earth as viewed by CASSINI from Saturn.
(Image:NASA

Indeed, Cassini's inevitable death brings an opportunity for riskier and courageous flyby close to the planet and its rings. Some tricky moves using Titan's gravity has altered the trajectory of Cassini which has resulted in GRAND FINALE.

It fills my heart with joy that right now a human build spacecraft is piercing through Saturn but at the same time little melancholic because the spacecraft will die this year. But the bright side is that as the participation of wider public increases, future science mission to these worlds might become reality.

By learning more about other planets and moons, our understanding of earth gets better. The appreciation of our world gets deeper. Humans are meant to explore and these mission feeds our constant need to know more about the universe. The famous quote of T.S Eliot can aptly summarise the entire space related quests. 

"We shall not cease from exploration. And the end of all our exploring will be to arrive where we started and know the place for the first time.."