Tuesday, September 18, 2007



By Deirdre Kelleghan Published Irelands Own December 2005

Artist’s conception shows Cassini –Huygens releasing the Huygens probe to Titan Image courtesy of NASA/JPL


Cassini –Huygens is a spacecraft on a mission to explore the planet Saturn and the many moons of this giant world. Titan is Saturn’s largest moon and is particularly targeted for study. This spacecraft blasted off from Cape Canaveral Florida in October 1997 over seven years ago. To put the year in context that was the year that princess Diana died, Gianni Versace was killed, comet Hall- Bop was visible in our sky’s and the movie Titanic was on our screens. Traveling every day since then at an average speed of 54,000 miles per hour this surely is an epic journey.


Cassini –Huygens is a robotic ship controlled from Earth on its journey of 3.5 billion miles, In July of this year Cassini went into orbit around Saturn and began its scientific study of this beautiful planet unique for its magnificent rings, its mysterious magnetosphere and its many moons (33 to date). This spaceship in made up of the Cassini main ship which carries on board the smaller Huygens probe. This mission is really science fiction becoming fact- Cassini is the largest spacecraft ever launched form earth, it is the size of a school bus and weighs 12,288lb, and is two stories tall, the Huygens probe is 8.86feet in diameter and weighs 766lb. Studying Saturn and its rings and moons may give us many clues to the origin of our solar system. A detailed examination will help us find out about the material from which Saturn is formed and evolved. The planet’s atmosphere is very interesting, with winds among the fastest in our solar system. Titan, Saturn’s largest moon holds unique mysteries, what is the surface made off? Information from the Hubble Space Telescope suggests there may be continents as well as oceans and lakes of liquid ethane on Titan. What kind of a place is this with chemical reactions in the atmosphere creating a variety of organic molecules that clump together and rain slowly down to the alien surface below? Cassini and its Huygens probe will try to answer these and many other questions about the Saturnian system.


On Christmas day Cassini will release Huygens and the probe will start its 21-day decent to the surface of Titan. A day worth waiting for is January 14 2005 as this is the day the Huygens probe will parachute to the surface of Titan after its seven year journey to seek out new information and along with Cassini dramatically increase our knowledge of the solar system. The Huygens probe will gather information about Titans atmosphere, take many photographs and do other scientific wizardry, reporting back to Cassini all of these treats of information to the eagerly waiting scientists and news media here on earth. Cassini will tour the Saturnian system for four more years after that and I am sure will go down in history as one of NASA’s greatest achievements. You can follow this exciting mission on the Cassini Huygens website. http://saturn.jpl.nasa.gov/

The Christmas day release of the Huygens probe will be counted down on the website’s clock, days minutes and seconds to separation and then days minutes and seconds to one of the greatest achievements in the history of the exploration of our solar system touch down on Titan. You can become closely connected to this mission and the Saturn story by becoming a member of The Saturn Observation Campaign. This a project that gives amateur astronomers educators and enthusiasts of all abilities an opportunity to study the wonders of the beautiful planet Saturn. The Campaign encourages people to access a wide bank of knowledge about the planet Saturn and to share this information with others in their community. This project is also very much linked with the Cassini-Huygens Mission to Saturn and Titan.

The Saturn Observation Campaign is directed by NASA and JPL (JPL are the Jet Propulsion Laboratory Californian Institute of Technology, these are the people who manage the Cassini - Huygens Mission). The SOC website http://soc.jpl.nasa.gov/index.cfm gives an abundance of information about Saturn and the mission; these websites are an educators paradise and an enthusiasts dream. The SOC is targeted to bring Saturn and Cassini into the lives of people of all ages who are unaware of this jewel of a planet and the extraordinary efforts going on to understand it and further our knowledge of our solar system. To become a member of SOC you can fill out the application form on line or e-mail Jane Houston Jones at jane.h.jones@jpl.nasa.gov. Jane is the senior outreach specialist with the Cassini -Huygens Programme for NASA / JPL.and is a leading amateur astronomer in the United States of America.


The total mission effort expended will exceed 20,000 work-years, or roughly 2/3 what it took to build the Great Pyramid at Giza. Nearly 5,000 people have worked on Cassini at one time or another. The spacecraft is the size and weight of an empty 30-passenger school bus. It contains 12km/s of wire and 58 computers. The gravity-assist gains of 22 km/s for cruise and 35km/s for the Saturn tour would not be possible using normal rocket engines without consuming millions of kilograms of fuel. The swingbys of Venus and Earth alone save the equivalent of 75 tonnes of fuel. Cassini is designed to withstand the heat or 2.7 Suns. Cassini will travel 3.5 billion kilometres to reach Saturn and another 2.4 billion kilometres during its 4-year tour. The spacecraft reached a maximum planet relative speed of 1112.700 km/h just before it fired its main rocket engine to brake into orbit about Saturn .The narrow angle camera can read a newspaper headline at a distance of nearly 1.6 kilometres. The spacecraft is so steady when pointing its instruments that its rate of movement is 100 times less than a clock’s hour hand. Over two trillion bits of data will be returned, equivalent to 2,400 sets of the Encyclopaedia Britannica. All of this information is received by large radio telescopes that must capture a signal whose power level is only 20 billionths of a billionth of one watt. Each of the three 70 meter Deep Space Network antennas used is as large as a football field. The signal typically takes at least an hour to reach the Earth from Saturn. The spacecraft will be carrying a small DVD containing 616,400 signatures from 81 different countries, including the signatures of Jean-Dominique Cassini and Christiaan Huygens the 17th century astronomers. Their signatures were scanned in from ancient manuscripts and are very appropriately included on the disc. If Saturn’s rings were around the earth they would stretch almost to the moon, as they are 200.000 miles in diameter.

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