Cassini - Huygens Mission

Saturn has always been among the favourite planets of most children due to its uniqueness with the rings around it, and also since it has a staggering count of Moons which total sixty when the objects orbiting it a few kilometres across are also counted.

In the list of planetary missions, the most important mission regarding Saturn is the Cassini-Huygens Mission, which tries to explore Saturn as well as its Moons. Therefore, it’s worth looking at it since the Cassini orbiter is still sending test results and it did the 44th flyby of Titan, the largest moon of Saturn on March 23, 2008.

Goals of the mission

Saturn is an exciting planet and something that brings a million questions to one’s mind. Even though it is situated 762,760,000 miles away from Earth and despite all the challenges, astronomers have come up with this mission to achieve a few important goals.

A prime goal is to determine the three-dimensional structure and dynamic behaviour of the rings of Saturn. Since there is a large number of Moons orbiting Saturn, astronomers have become interested to find out whether each of them possesses any special characteristics.

Therefore, the second goal is to determine the composition of the surface and the geological history of each Moon.

The Moon Iapetus is known to be the strangest Moon of Saturn since one side is dark with a slight reddish colour while the other is bright. Since there has been no valid explanation for this phenomenon, determining the nature and origin of the dark material on Iapetus’ dark hemisphere is a goal of this mission.

Additionally, measuring the behaviour of Saturn’s atmosphere at various levels and studying in detail about Titan in terms of its atmosphere and surface are other goals.

Important events

The journey that the Cassini made can be described as a journey which one would dream to make in one’s lifetime. It has gone past Venus, the Moon, a few asteroids, Jupiter and is now orbiting while observing the many Moons of Saturn. And what’s more?

The Cassini spacecraft has taken breathtaking snapshots and sent them to Earth all along its journey, just like we would do during a trip. In addition to taking pictures, it also has performed many tests and measurements on the way.

Casino made its closest approach to Jupiter in December 2000, and took many scientific measurements. About 26,000 images of Jupiter were taken during the flyby which took about a month. It has produced the most detailed picture of Jupiter yet and the smallest visible features captured are about 60 km across.

Using images taken by Cassini, three new moons of Saturn were discovered in 2004. They are very small and were named Methone, Pallene and Polydeuces at the beginning of 2005.

On May 1, 2005, another new moon was discovered by Cassini in the Keeler Gap of the ring system, which was named Daphnis. In addition, the orbiter has made many other important discoveries which we would carry in the next edition since each of them is so exciting.

Mission in brief

The mission is a joint project of NASA and the European Space Association. The spacecraft launched had two parts which were the Cassini orbiter and the Huygens probe. The orbiter was to orbit Saturn and its Moons and study each of them, while the probe was targeted at investigating Titan.

The Cassini orbiter is known to be the first orbiter of Saturn although it is the fourth spacecraft to reach Saturn. Voyager 1, Voyager 2 and Pioneer 11 have reached Saturn in early points in time.

The mission was named in order to respect the Italian-French astronomer Giovanni Domenico Cassini, and the Dutch astronomer, mathematician and physicist, Christian Huygens. The entire project has cost 3.26 billion dollars and seventeen countries have contributed to make the mission a reality.

The Cassini Huygens spacecraft was launched on October 15, 1997 from Cape Canaveral Air Force Station’s Launch Complex and it was only in July 2004 that it entered Saturn’s orbit after a long journey of nearly seven years. The Huygens’ probe separated from the orbiter in December 2004 and reached Titan in January 2005.

However, the way that the long journey was planned is extremely interesting, and it would be obvious that such a long journey cannot be relied on power sources for propulsion alone.

The technique that the spacecraft used is known as a gravity-assist technique. What happens in this situation is, the spacecraft approaches a few planets on the way and ‘steals’ a little of their orbital energy and as a result the speed of the spacecraft is increased.

During its trip to Saturn, the Cassini spacecraft has done two gravity-assists at Venus, one at Earth and the last at Jupiter and it has been up to speeds of a few kilometres per second.

To be continued

Compiled by Aravinda Dassanayake