All about Cassini-Huygens, the space mission for Saturn
On 15th October 1997, the United States–European space mission ‘Cassini-Huygens’ was launched to Saturn. Since then, we’ve known more about Saturn than ever before! Cassini spacecraft helped us visualise the structure of Saturn’s rings. It also revealed two moons, Titan and Enceladus, as prime targets to explore life on other planets! Do you wish to know more about this spacecraft? Then, without further ado, let’s learn about the history of Cassini, its achievements and legacy as the first probe to orbit Saturn!
Cassini–Huygens mission at a glance
NASA, the U.S. National Aeronautics and Space Administration launched Cassini–Huygens to study Saturn and its rings and moons on 15 October 1997. This was one of the biggest interplanetary spacecrafts, with a length of 6.7 m, a width of 4 m and a weight of 2,125 kg. The Cassini-Huygens mission's goals were to research Saturn's rings, many of its moons, and atmosphere, the region of space impacted by Saturn's magnetic field.
For this mission, the spacecraft had two components - Cassini and Huygens! Gian Domenico Cassini, a French astronomer, who discovered four of Saturn's moons and the Cassini divide, a sizable void in Saturn's rings, was the inspiration behind the name Cassini. And what about Huygens? Huygens was chosen as the name in honour of the Dutch astronomer Christiaan Huygens, who discovered Titan and its rings.
The two components had different functions. The component named Cassini was an orbiter that helps the spacecraft orbit around, whereas Huygens was a probe that helps collect data. In April 1998, Cassini–Huygens passed by Venus performing a Gravity-Assist flyby (A technique that helps spacecraft move faster or slower). Then in August 1999 and December 2000, it swung past Earth and Jupiter, respectively. So, when did it reach Saturn? On July 1, 2004, Cassini–Huygens began its orbit around Saturn.
You might think that the actual work started after the spacecraft entered Saturn’s orbit. But no! Cassini was at work even during its flyby! Its spectrometer identified water on the moon’s surface during its flyby of Earth. This information was later utilised in 2009 to validate the Indian probe Chandrayaan-1’s discovery of trace amounts of water on the moon surface.
Cassini–Huygens: Separation and much more
After entering Saturn’s orbit, Huygens was set free from Cassini on 25th December 2004. Eventually, Huygens settled on Titan on 14th January 2005. During its final descent of 72 minutes, it sent 350 images of a river delta and a coastline on Saturn’s surface with erosion features!
Now, this mission was all Cassini’s, and there was a lot in hold for this spacecraft!
After separation from Huygens, Cassini kept going around Saturn, making frequent rounds of its moons, for 13 long years! The most interesting discoveries made during the expedition were geysers of water ice and organic compounds at Enceladus’s south pole. These geysers erupted from an underlying global ocean that could be a suitable environment for life. Cassini’s radar also discovered large lakes of liquid methane on Titan. Furthermore, Cassini identified two new Saturn rings and six additional moons!
A Grand Finale for Cassini
Mission planners decided that upon completion of the mission, Cassini would launch into Saturn, where it would burn in the planet’s dense atmosphere. This was done to ensure that Cassini does not pollute Titan or Enceladus (moons of Saturn) with microbes from the Earth. So, as scheduled, on 22nd April 2017, Cassini started the first phase of its ‘Grand Finale’ mission after spending 13 years in Saturn’s orbit.
Cassini flew between Saturn and its innermost rings for the following 5 months. Then on 15th September 2017, Cassini entered Saturn and relayed data regarding the planet’s atmosphere before breathing its last. Interestingly, our brave old Cassini kept contact with NASA for 30 seconds longer than expected! Exactly as intended, the spacecraft continued to collect data until the very end and outperformed the mission team’s expectations during its final moments. Scientists will examine its data sets for years to come. Even though Cassini is no longer with us, its influence will endure long and other missions may soon follow the path set by it!