On September 15, an amazing 20 year mission of exploration and discovery came to an end… or did it?
Cassini-Huygens, often called just Cassini for short, has been a NASA and ESA “big science” program to study the planet Saturn and its moons. On the way, the spacecraft also flew by and took pictures of Venus, the Earth-Moon system, a small asteroid called 2685 Masursky, and the giant gas planet Jupiter.
The real excitement came over 6 years after launch when Cassini slipped into orbit around the Saturn system. The planet itself was a prime objective of the mission. But also important were penetrating and studying the thin ring system that gives Saturn its famous look, and getting a detailed look at Saturn’s many moons. As it turned out, Saturn has 62 moons with confirmed orbits. Six were discovered during the course of Cassini’s nearly 300 orbits of Saturn over 13 years.
So, where does the name Cassini come from? No, it’s not an Italian word to describe the spacecraft. It’s also not the name of the inventor of the mission. Giovanni Domenico Cassini was the 17th century astronomer who discovered the rings of Saturn and 4 of its moons. Laster he moved to France and set up the Paris Observatory for King Louis XIV.
Huygens Visits Titan
Christiaan Huygens, the other name in Cassini-Huygens, was a contemporary of Cassini and a famous astronomer in his own right. Huygens, a Dutch mathematician and scientist, also studied the rings of Saturn and discovered the moon Titan. Half again as large as Earth’s Moon, Titan has a thick atmosphere and rocky surface with water ice present.
How do we know? A landing craft called the Huygens probe hitched a ride on the side of the Cassini spacecraft. It split off from Cassini and dropped through the thick clouds of Titan in January, 2005. Scientists thought Huygens might wind up bobbing in an ocean, but it turned out that the probe landed on a flat plain with clusters of rocks and globules of frozen water. The photographs sent back during the 90 minutes Huygens functioned on the surface showed an orange colored sky bathed in twilight illumination.
The Shock of Enceladus
If there is a compelling reason to mount another major mission to Saturn ASAP, it is the discovery of the smooth white icy moon Enceladus.
Why? Because Enceladus is no quiet moon. Over 100 geysers shoot plumes of salt water into space. It’s eccentric orbit and interaction with another moon, Dione, cause Enceladus to stretch and shrink, which results in internal heating. Could there be an subsurface ocean here? Most likely. Does it contain life? Consider the strange lifeforms found at the bottom of Earth’s ocean trenches near hot water plumes and you’ve got to wonder.
Cassini Gone, Its Legacy Goes On
The spacecraft itself is no more. It was deliberately sent plunging into Saturn’s dense atmosphere as a man-made shooting star in September. Why do that instead of just letting it orbit Saturn and its moons indefinitely as a monument to humanity’s better instincts? The scientists in charge were too concerned that once Cassini ran out of fuel and became uncontrollable, it might someday cross the orbit of Titan or Enceladus and go crashing in, only to spew Earth organisms into any alien biologies. That could ruin our chances to find indigenous life beyond the Earth and wreak who knows what havoc.
The Cassini and Huygens crafts might be gone, but their wealth of data will live on. It has been predicted that dozens or even hundreds of PhD theses will be based on the 635b GB of data and over 450, 000 images collected during the mission. Almost 4,000 scientific papers have been published to date. It seems likely that even without followup missions soon, Cassini has given us enough of a data dump to fuel the careers of a new generation of scientific minds. It’s probably the best $4 billion we’ve spent in the last 20 years.
Note: Find T-shirts, coffee mugs, puzzles, greeting cards and more to celebrate the Cassini-Huygens Mission to Saturn in our Zazzle collection. Proceeds go to support elephant conservation worldwide, another personal passion.