Words Katrina T. Rivere
While Spirit and Opportunity are uncovering the secrets of our red-planet neighbor, Mars, the Cassini
spacecraft is exploring a different world altogether. After an interplanetary cruise spanning almost seven
years, the Cassini-Huygens mission reached Saturn on June 30, 9:12p.m. PDT.
Launched from Cape Canaveral Air Force Station in Florida on October 15, 1997, the Cassini space probe
traveled nearly 3.5 billion kilometers to reach Saturn. This kicks off a US$3.3 billion four-year mission to
study the giant ringed planet, its rings, moons and magnetosphere.
Saturn has puzzled astronomers and scientists ever since Galileo first looked at the planet through a telescope
in 1609. The Italian astronomer had seen some sort of "arms" that grew and disappeared for unknown reasons.
In 1659, 17 years after Galileo died, Dutch Scientist Christiaan Huygens pronounced that the "arms" that Galileo
saw were, in fact, a set of rings.
An Earth-like world
Titan, one of Saturn's 31 known moons and also the largest, is by far its most intriguing natural satellite.
Haze-covered Titan has two major components of Earth's atmosphere - nitrogen and oxygen, although
scientists believe the oxygen is likely frozen.
Because Titan and Earth share so much in atmospheric composition, this satellite is thought to hold clues as
to how the Earth evolved. Scientists also hope to learn what many of Saturn's moons are made of and whether
they contain elements that are considered to be the building blocks of our solar system and of life itself. Over the
course of the Cassini mission, scientists expect to discover and understand more about the Earth and Saturn, as well
as phenomena in the fields of biology, atmospheric chemistry and physics, climatology, and others.
The mission
This trip to Saturn is the result of three different space agencies all working together - NASA, the European
Space Agency (ESA) and the Agenzia Spaziale Italiana (ASI) - and more than 200 scientists scattered throughout
19 countries. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena,
manages the Cassini-Huygens mission for NASA's Office of Space Science in Washington. The Cassini orbiter and
its two onboard cameras were designed, developed and assembled at JPL. Of the 265 scientists involved with the
mission, only 125 live in the US. That means there are teleconferences across time zones, with scientists in one
part of the world getting up early while their colleagues in another time zone are putting their kids to bed.
The Cassini spacecraft, including the orbiter and the Huygens probe, is one of the most complex spacecraft ever
built, not to mention one of the largest and heaviest. It has 22,000 wire connections and more than 14 kilometers of
cabling. Electrical power is supplied by a set of radioisotope thermoelectric generators. The Cassini spacecraft will send
back to Earth more than 300,000 color images of Saturn, its rings, Titan, and other moons. Around a thousand images of
Titan will be taken by the Huygens probe when it plunges through the hazy atmosphere of Titan in December.
Saturn is the sixth planet from the sun and is the second largest planet in our solar system after Jupiter. The
planet-and-ring system serve as a miniature model of the disc of gas and dust surrounding our early sun that eventually
formed the planets. Detailed knowledge of the interactions among Saturn's elaborate rings and numerous moons will
provide valuable data for understanding how each of the solar system's planets evolved.
On June 11, the spacecraft came within 1,250 miles of Phoebe, a dark, icy moon that orbits Saturn in the opposite
direction of all its other known moons. Phoebe harbors pockets of frozen carbon dioxide, a trait that makes it highly
likely that this particular moon originated in the Kuiper belt, a region of debris left over from the birth of the solar system.
