Over in the Space Track, Forsythe (Hil), NASA scientist Trina Ray spoke about the latest and greatest discoveries from the Cassini-Huygens mission to Saturn. The Cassini Spacecraft launched on October 15th, 1997, and took seven years to reach Saturn. The four-year prime mission called for 75 orbits of Saturn, 45 targeted flybys of Titan, eight targeted icy satellite flybys, as well as the launch of the Huygens probe, which landed on Titan on January 14th, 2005. The total cost for NASA was $3 billion.
The good news is that the primary mission, which ended in July of 2008, has been extended by two more years, concluding July 1, 2010. The extra time will allow scientists to capture Saturn’s equinox, when the rings are directly edge on with the sun.
Ray organized her talk like a Top Ten list, listing the aspects of the mission in order of greatness. But with so many exciting chunks of information goodness, she only had time for nine.
Number One: The Huygens Probe
Because of Titan’s thick atmosphere, little was known about the moon which closely resembles Earth. The Huygens probe descended for two hours and 27 minutes and transmitted from the surface for one hour and 12 minutes. If you study chemistry, Titan is the body you should focus on. It’s so cold that all of its water is frozen solid; it even has ice volcanoes. Covered with varying forms of hydrocarbons, Titan has no oxygen. If it did, the whole place would blow up. Its total surface area is about the same size as the United States.
Number Two: Enceladus
Much smaller, the total surface area of the moon Enceladus is about the size of Iowa. It is covered with soft surface craters and has a warm south pole. The first anomaly discovered about Enceladus is that it has an effect on the magnetic field of Saturn. The how and why has not yet been determined. Second, the moon actually has a huge geyser that shoots regularly from it. In March and August this year, the Cassini craft looked into the plume. The uniqueness of this particular feature is so intriguing that scientists can’t wait to learn more during the extended equinox mission.
Number Three: Titan
Along its equator, the dark portions of Titan are gigantic sand dunes. In the northern hemisphere, the dark parts are lakes of liquid methane. Unlike Mars, Titan has a strong interactive relationship between its surface and the atmosphere. Photos from Cassini have shown mountains, lakes, drainage channels, huge cloud systems, wind driven dunes, river channels, and very few craters.
Number Four: Iapetus
This Saturn moon is a strange and icy world. For 300 years, scientists have been arguing over the mystery of Iapetus’s black and white regions. With the Cassini data, they have concluded that the white parts are ice and the dark parts are a combination of dirt, carbon dioxide, and rocky silicate. The moon is tidally locked to Saturn and takes 80 days to rotate, giving it 40 “days” of day and 40 of night. The resulting extended periods of heating and cooling are largely responsible for the distinctive differences between the black and white portions. The other cool feature of this moon is its huge ridge right along the equator that makes the moon look as though it were made with a cheap injection mold and the edges weren’t smoothed over. This ridge is 20 kilometers high.
Number Five: Saturn Orbit Insertion Trajectory
For 96 minutes of Ray’s life, she and the other scientists were riveted to the monitors, watching Cassini’s path through the rings. Although they didn’t learn much about the B-ring, they did get volumes of information on the F-Ring.
Number Six: The F-Ring
Cassini caught some of Prometheus’s path through the rings, including it pulling F-Ring debris as it passed into and then out of the ring during its orbit. The F-Ring has a very dynamic, dramatically changing core structure.
Number Seven: Saturn’s Depths
Infrared shots of Saturn show it’s more like Jupiter. The primary Cassini mission has followed the planet through its spring, during which the rings cast a shadow on the northern hemisphere. There, dust settles in the cooler spots causing clumping. Information on the hurricane at the south pole may help scientists to understand hurricanes here on Earth. Images of the north pole show a hexagon feature.
Number Eight: Saturn’s Rotation
Ratio emissions used to calculate the speed of rotation of Saturn have revealed an interesting phenomenon. When Voyager passed Saturn, its rotation was calculated to be ten hours and 39 minutes. The Cassini numbers show it to be ten hours and 45 minutes. This discrepancy is baffling mission scientists.
Number Nine: Hyperion
In September of 2005, images from the 514 kilometer flyby of Hyperion revealed new information on this sponge-look moon. What appeared to be deep shadows were actually deposits of black gunk burrowing into the lighter parts of the surface components. This small moon is not tidally locked and not round, which makes it rotate chaotically.
For more information, visit the home page of the mission.