NASA's Cassini Spacecraft Continues Making New Discoveries

Feb 24, 2005
A natural color view of Saturn taken by the Cassini spacecraft on its approach to the planet
A natural color view of Saturn taken by the Cassini spacecraft on its approach to the planet

NASA's Cassini spacecraft continues making new and exciting discoveries. New findings include wandering and rubble-pile moons; new and clumpy Saturn rings; splintering storms and a dynamic magnetosphere.
"For the last seven months it has been a nonstop, science-packed mission. It has been a whirlwind, and already we have many new results," said Dr. Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Weak, linear density waves caused in Saturn's rings by the small moons Atlas and Pan have yielded more reliable calculations of their masses. The masses imply the moons are very porous, perhaps constructed like rubble piles. They are similar to the moons that shepherd Saturn's F ring, Prometheus and Pandora.

Another discovery was a tiny moon, about 5 kilometers (3 miles) across, recently named Polydeuces. Polydeuces is a companion, or "Trojan" moon of Dione. Trojan moons are found near gravitationally stable points ahead or behind a larger moon. Saturn is the only planet known to have moons with companion Trojan moons.

The new findings, published in this week's edition of the journal Science, include refinements in the orbits of several of Saturn's small satellites. One intriguing result is the eccentric and slightly inclined orbit of Pan in Saturn's A ring. The orbit's shape is significant, as it indicates the type of interaction the moon has with the ring material surrounding it. If Pan's orbit remains eccentric due to this interaction, then planets growing in a disc of material surrounding a star may also have eccentric orbits. This may help explain the eccentric paths of planets orbiting other stars.

Several faint Saturn rings have been discovered in Cassini images. Some lie in various gaps in the rings and may indicate the presence of tiny embedded moons acting as shepherds. Several of the rings are kinked, likely evidence of nearby moons.

Scientists also found Saturn's winds change with altitude, and small storms emerge out of large ones. For the first time, Cassini images captured possible evidence of processes that may maintain the winds on Saturn. The observations offer a glimpse into the process which transfers energy by convection from Saturn's interior to help sustain strong winds.

Other results improve the understanding of Saturn's complex magnetic environment. "Saturn's magnetosphere is truly unique. It's dynamically similar to Jupiter's, but in places it chemically resembles water-based plasmas surrounding comets," said Dr. David Young. Young is Cassini principal investigator for the plasma spectrometer instrument from the Southwest Research Institute, San Antonio.

Another surprising find was made by the ion and neutral mass spectrometer instrument, which measured molecular oxygen ions above Saturn's ring plane. "This is at first surprising since the rings are made of water ice," said Dr. Hunter Waite, principal investigator for the spectrometer from the University of Michigan, Ann Arbor. "This may have important consequences for the identification of spectral features to use in the search for life on extrasolar terrestrial planet systems."

The abundance of molecular oxygen on Earth is uniquely tied to biology. But these new measurements at Saturn suggest there are lifeless processes associated with cold icy surfaces that may produce an independent pathway for the formation of molecular oxygen in atmospheres.


Explore further: Spacewalking astronauts finish extensive, trick cable job

add to favorites email to friend print save as pdf

Related Stories

Life on Europa? Scientists ponder the possibilities

Feb 19, 2015

When Galileo viewed Jupiter through his telescope in 1610, he saw four dim objects near it that he assumed were stars. Repeated observations revealed that these "stars" orbited Jupiter like our own moon circles ...

A new way to view Titan: 'Despeckle' it

Feb 14, 2015

During 10 years of discovery, NASA's Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn's largest moon. Cassini's radar instrument has mapped almost half of the ...

Which planets have rings?

Feb 06, 2015

Planetary rings are an interesting phenomenon. The mere mention of these two words tends to conjure up images of Saturn, with its large and colorful system of rings that form an orbiting disk. But in fact, ...

Cassini catches Titan naked in the solar wind

Jan 29, 2015

(Phys.org)—Researchers studying data from NASA's Cassini mission have observed that Saturn's largest moon, Titan, behaves much like Venus, Mars or a comet when exposed to the raw power of the solar wind. ...

Some of the best pictures of the planets in our solar system

Jan 19, 2015

Our Solar System is a pretty picturesque place. Between the Sun, the Moon, and the Inner and Outer Solar System, there is no shortage of wondrous things to behold. But arguably, it is the eight planets that make up our Solar ...

Recommended for you

Giant methane storms on Uranus

51 minutes ago

Most of the times we have looked at Uranus, it has seemed to be a relatively calm place. Well, yes its atmosphere is the coldest place in the solar system. But, when we picture the seventh planet in our ...

Why we see familiar-looking objects in Mars topology

1 hour ago

What is up with the fossils on Mars? Found – a dinosaur skull on Mars? Discovered – a rat, squirrel or gerbil on Mars? In background of images from Curiosity, vertebrae from some extinct Martian species? ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.