Blastoff to Saturn
Only three spacecraft have ever visited Saturn. Pioneer 11 flew by at a distance of 22,000 kilometers (13,000 miles) in 1979. Voyager 1 flew 124,000 kilometers (77,000 miles) above Saturn's cloudtops in 1980, showing us a close look at Saturn's large moon Titan and sending back stunning images of Saturn and its rings. Voyager 2 flew by Saturn at a distance of about 100,000 kilometers (62,000 miles) in 1981. In the early moonlit morning of October 15, 1997, Cassini launched from Cape Canaveral in Florida, to join these three trailblazing spacecraft on its voyage to Saturn.
The above image is an artists' rendition of the Cassini spacecraft approaching the planet Saturn and its magnificent rings. The glint of light behind the magnetometer boom at the bottom of the spacecraft represents the reflection of the sun. Since Saturn is 930 million miles away from the sun, and consequently, about 746 million miles away from Earth, from this perspective one can get a sense in the image just how far the Cassini spacecraft has to travel to reach the mysterious ringed planet.
Image credit: NASA/JPL-Caltech
Cruise and tour
The Cassini-Huygens mission has two major phases: cruise and tour. Cassini has been in the cruise phase of the mission since 1997. The Cassini-Huygens mission is not unlike planning a vacation, where the cruise phase would entail referring to maps along the journey, and the tour phase would be to explore and take pictures upon arrival at the destination.Fast forward to 2004
Cassini is now approaching the tour phase of the mission. In just a few months Cassini will fly by the moon Phoebe. Less than a month later, the Cassini spacecraft will execute the dramatic Saturn Orbit Insertion or SOI.
This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. The spacecraft is moving out of the plane of the page and to the right (firing to reduce its spacecraft velocity with respect to Saturn) and has just crossed the ring plane. The SOI maneuver, which is approximately 90 minutes long, will allow Cassini to be captured by Saturn's gravity into a five-month orbit. Cassini's close proximity to the planet after the maneuver offers a unique opportunity to observe Saturn and its rings at extremely high resolution.
Image credit: NASA/JPL-Caltech
On to Titan
Then, just 6 months later, the Cassini orbiter will release the Huygens probe for a three-week coast toward Saturn's largest moon, Titan. After atmospheric entry and a parachute deployment, Huygens will descend into the atmosphere of Titan.
The Cassini-Huygens mission to Saturn and Titan represents a rare opportunity to gain significant insight into major scientific questions about the creation of the solar system and primordial conditions on Earth. During the four-year Saturn Tour, Cassini will complete 74 orbits of the ringed planet, 44 close flybys of the moon Titan, and numerous flybys of Saturn's other moons Dione, Iapetus, Enceladus, Mimas, Tethys, Hyperion, Rhea, and Epimetheus.
Cassini's payload represents a set of interrelating instruments that will address many scientific questions about the Saturn system. Nearly 300 scientists from the United States and Europe will analyze the data. Five broad categories encompass the science of the Cassini-Huygens Mission.
|Saturn Why does Saturn's atmosphere show fewer features than Jupiter? Why does Saturn have the fastest jet streams in the solar system?|
|Titan What goes on beneath Titan's atmosphere? Are there continents or oceans beneath? What processes occur in such a cold environment? Will the chemistry of Titan help us understand the evolution of early life on Earth?|
|Rings Will the rings reveal information about how Saturn evolved? Why are there wave patterns, gaps and moonlets embedded in the rings?|
|Magnetosphere Sensors will study the magnetic field structure, neutral and charged particles and the radio waves generated by interactions of the magnetosphere with the solar wind and with bodies in the Saturn system. Cassini will open an observational window into this study.|
|Icy satellites Does the water ice moon Enceladus have an internal heat source that erases impact craters? Why is Iapetus white as snow on one half and black as asphalt on the other?|
Cassini Education programs
As Cassini nears its destination, students can learn about the fascinating planet Saturn as well. There is a wealth of educational material on the Cassini-Huygens Mission and Solar System Exploration websites from which to choose:
While scientific discovery is the impetus for the K-4 Education program, the unique focus is to use the Cassini-Huygens Mission as contextual framework to improve crucial reading and writing skills in elementary schools across the country.
Scientific engagement is the focus of the Cassini 5-8 Program, and it stresses an interdisciplinary hands-on approach to science learning at the middle grades in an effort to reach students who otherwise would not be exposed to such subject matter.
The 9-12 program will encourage guided training and image-processing software to aid in the education of analyzing real mission data.
There are many other classroom activities for educators and students of all levels. Presentations, slide sets, printed materials and references are widely available.
Below are some examples of specific Cassini-Huygens Mission educational activities that span all grade levels:
Grade level 6-12 Can photosynthesis occur at Saturn? Analogy: Titan and Saturn
Grade 3 - 12 Planetary Billiards Analogy: Cassini's tour of Saturn system using Titan for gravity assist trajectory modifications.
Grade 5 - 12 Sand or rock? Finding out from 1,000 kilometers (600 miles). Analogy: Remote sensing of thermal properties in the Saturn system.
Grade 5 - 12 Scattering: Seeing the microscopic among the giants Analogy: The rings and atmospheres of Saturn and Titan
Grades 5 - 12 Unveiling Titan's surface Analogy: Titan's surface unveiled by Cassini radar
Grade 6 - 8 Capturing a whisper from space Analogy: How a worldwide series of antennae communicate with interplanetary spacecraft such as Cassini
Grades 1 - 4 Edible Cassini Spacecraft Analogy: Cassini orbiter and Huygens probe
Make a Gingerbread Cassini. Paper models too.
Titan in a fish tank.
These activities and links are certain to whet the appetite of explorers and inquirers of all ages as we watch and learn from the mission's discoveries made at the mysterious planet Saturn and its largest moon, Titan.
About the Author
Jane Houston Jones served on the board of directors of the ASP from 2000 - 2003 and has been active in Project ASTRO in the San Francisco Bay Area for many years before joining the NASA JPL Cassini-Huygens outreach team in late 2003.
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