The Cassini Mission was an audacious idea from the start.

Get the world's best space scientists and engineers to build the best and hardiest instruments that they can to study Saturn. Put everything on a spacecraft and launch it to the outer solar system.

Loop twice around Venus, once around Earth, then pass Jupiter. When you get to Saturn, veer right and slam on the brakes. Pass through the rings. Look out for those ice particles! Start orbiting Saturn.

Hang out a lot at Titan - it's smoggy but that's where the action is. Drop off the Huygens Probe there and tell us everything it has to say about what it finds.

Check out Enceladus; something strange is going on there. Go by Iapetus. It is definitely weird. There are a bunch of little moons hiding in and around the rings, making waves and kicking up dust. Find them. And fly way up above Saturn a few times. We've never seen it from that view. Be open to the unexpected. Stay for at least four years. Report back on everything that you see, feel, smell and hear. Take lots of pictures!

Astonishingly, Cassini's historic prime mission has successfully concluded. It may have looked easy, but the mission's success is owed to the careful and hard work of the dedicated international team that built and operates the spacecraft. Now, Cassini embarks on the new Equinox mission with a fresh set of scientific objectives.

Since arriving at the ringed planet four years ago, Cassini has revealed wonder after wonder. The growing body of knowledge about Saturn, its rings, moons and magnetic environment is allowing scientists to link together clues to solve mysteries. For every puzzle solved, Cassini seems to raise 10 more new questions - a happy predicament for scientists.

Some highlights of the prime, four-year Cassini mission:

* Geysers shoot water vapor and ice from warm fissures on Enceladus.
* The E-ring of Saturn is made of material from Enceladus' plumes.
* Material from Enceladus' plumes adds mass to Saturn's magnetosphere and slows the rotation of Saturn's magnetic field.
* Comet-like organic chemicals exist in Enceladus' plumes.
* Titan appears to be land of lakes, with hundreds of lake features, probably filled with hydrocarbons.
* Titan has a hydrological cycle like Earth's but substitutes methane for water in processes that include methane rain, clouds and apparently, lakes.
* Braided channels are carved in Titan's surface -- evidence of heavy flooding.
# Small moons, including Hyperion, are dazzlingly varied and strange.
* Sahara-like sand dunes exist on Titan, and the sand is probably made up of hydrocarbons that fall from the sky.
* An internal ocean likely exists on Titan. It causes Titan's crust to slip about "like cheese on pizza sauce."
* Evidence exists for a tenuous ring system around the moon Rhea.
* An odd mountain ridge runs around Iapetus' equator.
* Detailed studies of Iapetus, frozen in time, shed new light on the early formation of other bodies in the solar system.
* The Huygens Probe returned the first close-up views of Titan's haze-covered terrain.
* Landing onto damp, icy gravel or sand at edge of a dried-up methane lake, the Huygens Probe provided new insight into the makeup of Titan.
* Titan is losing its atmosphere due to bombardment by Saturn's magnetosphere.
* Extremely heavy organic compounds, up to 10,000 times heavier than hydrogen - were found high in Titan's atmosphere. These become aerosols and eventually rain down onto Titan's cold surface - they may be the "tholins" predicted by Carl Sagan that comprise a prebiotic chemical soup.
* Auroras at Saturn's north and south poles are unlike those found on Earth and Jupiter.
* Hot hurricane-like storms churn at both of Saturn's poles.
* The temperature structure of Saturn's and Titan's atmospheres were completely mapped, revealing their circulation and dynamics.
* The rings have their own atmosphere.
* Evidence was found that the rings may be a permanent rather than transitory feature of Saturn.