Cassini News from Scientific Frontline an online publication by SFL ORG. Educational News Network

Page Bookmarks

Cassini Intro | Current Top Article | Recent Articles | Saturn, The Jewel of the Solar System | Cassini Archive

Related Cassini Mission Pages

Cassini Mission Status | Cassini Gallery Main | Cassini Gallery 2006 | Cassini Gallery 2007 | Cassini Gallery 2008

Science Objectives

Credit: NASA / JPL

When considering such a complex, collaborative effort as the Cassini-Huygens mission, one might ask the question, "Why build it in the first place?"

The answer comes even before the mission's conception. At the beginning, a basic set of science goals are illustrated in a detailed, comprehensive mission plan that scientists hope to achieve and bring to the public at large.

In this case, through Cassini we hope to gain a better understanding of the planet Saturn, its famous rings, its magnetosphere, its principal moon Titan and its other moons or "icy satellites."

Along with extensive preparation, planning and tracking throughout the mission, science objectives are divided into two parts: The goals that occur on the way to the ringed planet, and then those that will occur after the mission's arrival at the Saturnian system.

The Cassini spacecraft is the first to explore the Saturn system of rings and moons from orbit. Cassini entered orbit on Jun. 30, 2004 and immediately began sending back intriguing images and data. The European Space Agency's Huygens Probe dove into Titan's thick atmosphere in January 2005. The sophisticated instruments on both spacecraft are providing scientists with vital data and the best views ever of this mysterious, vast region of our solar system.

Current Top Article

Saturn Does the Wave in Upper Atmosphere

Wednesday, May 7, 2008

Hi-Res Full Caption Labeled | Hi-Res Full Caption Unlabeled

Scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years.

Credit: NASA / JPL

Two decades of scrutinizing Saturn are finally paying off, as scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years.

The discovery of the wave pattern is the result of a 22-year campaign observing Saturn from Earth (the longest study of temperature outside Earth ever recorded), and the Cassini spacecraft's observations of temperature changes in the giant planet's atmosphere over time.

The Cassini infrared results, which appear in the same issue of Nature as the data from the 22-year ground-based observing campaign, indicate that Saturn's wave pattern is similar to a pattern found in Earth's upper atmosphere. The earthly oscillation takes about two years. A similar pattern on Jupiter takes more than four Earth years. The new Saturn findings add a common link to the three planets.

Just as scientists have been studying climate changes in Earth's atmosphere for long periods of time, NASA scientists have been studying changes in Saturn's atmosphere. Glenn Orton of NASA's Jet Propulsion Laboratory in Pasadena, Calif., says patience is the key to studying changes over the course of a Saturnian year, the equivalent of about 30 Earth years.

"You could only make this discovery by observing Saturn over a long period of time," said Orton, lead author of the ground-based study. "It's like putting together 22 years worth of puzzle pieces, collected by a hugely rewarding collaboration of students and scientists from around the world on various telescopes."

The wave pattern is called an atmospheric oscillation. It ripples back and forth within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern. These varying temperatures force the wind in the region to keep changing direction from east to west, jumping back and forth. As a result, the entire region oscillates like a wave.

A "snapshot" of the hot-cold temperature patterns in Saturn's atmosphere was captured by the Cassini Composite Infrared Spectrometer. Along with Earth-based data, the "snapshot" also uncovered other interesting phenomena. Among them: the temperature at Saturn's equator switches from hot to cold, and temperatures on either side of the equator switch from cold to hot every Saturn half-year.

Mike Flasar, co-author of the Cassini paper, and principal investigator for Cassini's Composite Infrared Spectrometer at NASA's Goddard Space Flight Center, Greenbelt, Md., said that Cassini helped define this oscillation in combination with the ground observation campaign.

"It's this great synergy of using ground-based data over time, and then getting up close and personal with the oscillation in Saturn's atmosphere through Cassini," said Flasar. "Without Cassini, we might never have seen the structure of the oscillation in detail."

Cassini scientists hope to find out why this phenomenon on Saturn changes with the seasons, and why the temperature switchover happens when the sun is directly over Saturn's equator.

Source: NASA / JPL

Permalink: http://www.sflorg.com/cassini/missionnews/casmn050708_01.html

Recent Articles

	Titan's Smoggy Sand Grains May 03, 2008 That's one theory Cassini scientists are considering after studying Titan's massive sand dunes with the visible and infrared mapping spectrometer on the Cassini Saturn orbiter. The new observations raise the possibility that much of the sand grows from hydrocarbon particulates fallen from the sky that, once on the ground, join together and become sand grain-size particles.
	NASA Extends Cassini's Grand Tour of Saturn Apr. 15, 2008 Cassini's mission originally had been scheduled to end in July 2008. The newly-announced two-year extension will include 60 additional orbits of Saturn and more flybys of its exotic moons. These will include 26 flybys of Titan, seven of Enceladus, and one each of Dione, Rhea and Helene. The extension also includes studies of Saturn's rings, its complex magnetosphere, and the planet itself.
	Cassini Spacecraft Finds Ocean May Exist Beneath Titan's Crust Mar. 26, 2008 NASA's Cassini spacecraft tasted and sampled a surprising organic brew erupting in geyser-like fashion from Saturn's moon Enceladus during a close flyby on March 12. Scientists are amazed that this tiny moon is so active, "hot" and brimming with water vapor and organic chemicals. New heat maps of the surface show higher temperatures than previously known in the south polar region, with hot tracks running the length of giant fissures. Additionally, scientists say the organics "taste and smell" like some of those found in a comet.
	Cassini Spacecraft Finds Ocean May Exist Beneath Titan's Crust Mar. 20, 2008 NASA's Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan. "With its organic dunes, lakes, channels and mountains, Titan has one of the most varied, active and Earth-like surfaces in the solar system," said Ralph Lorenz, lead author of the paper and Cassini radar scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Md., "Now we see changes in the way Titan rotates, giving us a window into Titan's interior....

Saturn / The Jewel of the Solar System

Saturn filled Cassini's narrow angle camera as the spacecraft approached in March 2004.

With its stunning rings and dozens of moons, Saturn is an intriguing planet for many reasons. The giant planet has a huge magnetosphere and a stormy atmosphere with winds clocked at about 1,800 kilometers per hour (1,118 mph) near the equator. These super-fast winds, combined with heat rising from within the planet's interior, cause the yellow and gold bands visible in its atmosphere.

Like Jupiter, Uranus and Neptune, Saturn is a gas giant. It is made mostly of hydrogen and helium.

Saturn's rings in true color.

'Jewel of the Solar System'

Saturn's beautiful rings are what set it apart from the other planets in our solar system. It is the most extensive and complex ring system in our solar system, extending hundreds of thousands of miles from the planet. Made up of billions of particles of ice and rock - ranging in size from grains of sugar to houses - the rings orbit Saturn at varying speeds.

There are hundreds of individual rings, believed to be made of pieces of shattered moons, comets and asteroids. Each of the billions of rings particles orbits the planet on its own path.

For centuries, Saturn and its rings puzzled observers. Italian astronomer Galileo Galilei, the first to use a telescope to explore space, couldn't understand why Saturn looked so different in the night sky at different times. We now know this is caused by a shifting in our view of the ring plane. The rings are virtually invisible when they are edge-on to Earth. The rings seem to reappear months later as our angle of view changes.

Despite tremendous advances in observations in the 400 years since Galileo began studying Saturn's rings, many questions remain about the composition and structure of the rings.

Titan's thick, hazy atmosphere.

Iapetus' light and dark terrain.

Many Moons

Saturn's 34 known moons are equally mysterious, especially Titan. Bigger than the planets Mercury and Pluto, Titan is of particular interest to scientists because it is one of the few moons in our solar system with its own atmosphere. The moon is cloaked in a thick, smog-like haze that scientists believe may be very similar to Earth's before life began more than 3.8 billion years ago. Further study of this moon promises to reveal much about planetary formation and, perhaps, about the early days of Earth as well.

In addition to Titan, Saturn has many smaller icy satellites. Some, like Pan, Atlas, Prometheus, and Pandora, are "shepherd moons" that herd Saturn's orbiting particles into distinct ring. Some moons produce twisting and wave patterns in the rings.

One moon, Enceladus, is one of the shiniest objects in the solar system. It's about as wide as Arizona and covered with water ice that reflects sunlight like freshly fallen snow. And strange Iapetus has one side black as asphalt and the other as bright as snow. All of Saturn's moons are unique and intriguing science targets.

Taking a Closer Look

Four NASA spacecraft have been sent to explore Saturn. Pioneer 11 was first to fly past Saturn in 1979. Voyager 1 flew past a year later, followed by its twin, Voyager 2, in 1981.

The Cassini spacecraft is the first to explore the Saturn system of rings and moons from orbit. Cassini entered orbit on Jun. 30, 2004 and immediately began sending back intriguing images and data. The European Space Agency's Huygens Probe is set to dive into Titan's thick atmosphere in January 2005. The sophisticated instruments on both spacecraft are providing scientists with vital data and the best views ever of this mysterious, vast region of our solar system.

Cassini-Huygens is an international collaboration between three space agencies. Seventeen nations contributed to building the spacecraft. The Cassini orbiter was built and managed by NASA's Jet Propulsion Laboratory. The Huygens probe was built by the European Space Agency. The Italian Space agency provided Cassini's high-gain communication antenna. More than 250 scientists worldwide are studying the data streaming back from Saturn on a daily basis.

Source / Credit: NASA / JPL