Circling Saturn: Carolyn Porco on her Celestial Trip

Apr 19, 2010 by ROBERT NAEYE
Photograph by Tony Rinaldo (c) 2010

(PhysOrg.com) -- Carolyn Porco is on a mission. As she explained to an audience of several hundred gathered at the Radcliffe Gymnasium earlier this month, in a lecture titled “At Saturn: Tripping the Light Fantastic,” this mission is nothing less than “to understand how our small planet came to be.”

Porco is the leader of the imaging team for NASA’s , which has been orbiting since July 2004. The giant ringed planet is so large that it could swallow about 1,000 Earths, and its magnificent rings would span almost the entire space between Earth and the Moon.

But it’s not just Saturn and its rings that fascinate Porco, a planetary scientist based at the Space Science Institute and the University of Colorado in Boulder. Saturn is the lord of 61 known moons, making it the centerpiece, she says, of “a rich, complex .” Two of them, Titan and Enceladus, hold special interest for Porco and her NASA colleagues, who believe these moons may help to answer questions about the origins of life. The researchers have identified several additional small moons, including one that orbits within the rings themselves.

Porco made her mark in the 1980s as a member of the Voyager imaging team, which used data from NASA’s Voyager 1 and 2 to study Saturn’s rings. In particular, she calculated how the of several small moons has sculpted the sharp edges of Saturn’s rings and narrow ringlets

Unlike the Voyagers, which flew past Saturn and will never return, the $3.4 billion Cassini has settled into orbit around the planet. Cassini is providing far superior images, which reveal new levels of detail and structure in the rings. As Porco explained to her audience during the last installment in the 2009-2010 Dean’s Lecture Series, the same physics and mathematics that govern the giant in galaxies like our Milky Way can explain waves in Saturn’s rings that were created by sizable moons. Some of the rings’ features give us a glimpse into the solar system’s distant past, when the planets were forming within a huge disk of gas and dust surrounding the Sun.

Saturn’s largest moon, Titan, is slightly larger than the planet Mercury, and the only moon to harbor a thick atmosphere. That atmosphere is dominated by nitrogen, just like Earth’s, but it also contains small amounts of methane. The methane plays the same role on Titan that water plays on Earth: It forms clouds, rains out of the atmosphere, and collects on the surface to create lakes oozing with organic compounds. Porco sounded choked with emotion when she described the brilliantly successful January 2005 landing on Titan of the European-built Huygens probe, which piggybacked its way to Saturn on Cassini. “This was an event that in my mind was so significant that it should have been celebrated with ticker-tape parades in every major city across the US and Europe,” she said.

But for Porco, the star of the Cassini show has been Enceladus, an ice ball about the size of Great Britain. “We knew it was intriguing from Voyager,” she said, “but what we found is startling.” Cassini images reveal jets of icy particles spraying hundreds of miles into space from the moon’s south pole. Cassini has flown through these plumes several times, and shows that they contain organic molecules such as carbon dioxide, methane, propane, and perhaps benzene. Not only do the plumes contain the stuff of life, but they seem to originate from salty water very near the moon’s surface. “We are more confident than we were five years ago that Enceladus presents an environment where prebiotic chemistry—and perhaps even life itself—might be stirring,” said Porco.

Cassini has already fulfilled all its mission objectives, but because the spacecraft remains in excellent health, NASA has extended its Saturn sojourn to 2017. Porco hopes that someday NASA will fly a follow-up mission to explore in more detail, to see if life has taken root. “Should we ever discover that a second genesis had occurred in our solar system, independently outside the Earth,” she said, “then I think at that point the spell is broken, the existence theorem has been proven, and we could safely infer from that that life was not a bug but a feature of the universe in which we live—that it’s commonplace and has occurred a staggering number of times.”

Explore further: Full lunar eclipse delights Americas, first of year

add to favorites email to friend print save as pdf

Related Stories

Looking for life beyond Earth

Apr 07, 2010

(PhysOrg.com) -- Scientist Carolyn Porco explored the deeper regions of the solar system and her work with the Cassini mission to Saturn during a talk at Radcliffe.

Saturn images to be displayed in New York

Apr 21, 2008

The National Aeronautics and Space Administration says some of the best images from Saturn and the planet's rings and moons will be displayed in New York.

Recommended for you

Vegetables on Mars within ten years?

22 hours ago

The soil on Mars may be suitable for cultivating food crops – this is the prognosis of a study by plant ecologist Wieger Wamelink of Wageningen UR. This would prove highly practical if we ever decide to ...

NASA Cassini images may reveal birth of a Saturn moon

23 hours ago

(Phys.org) —NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known ...

Meteorite studies suggest hidden water on Mars

23 hours ago

Geochemical calculations by researchers at Tokyo Institute of Technology to determine how the water content of Mars has changed over the past 4.5 billion years suggest as yet unidentified reservoirs of water ...

User comments : 0

More news stories

ESO image: A study in scarlet

This new image from ESO's La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that ...

Astronomers: 'Tilt-a-worlds' could harbor life

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...

NASA Cassini images may reveal birth of a Saturn moon

(Phys.org) —NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known ...

First direct observations of excitons in motion achieved

A quasiparticle called an exciton—responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits—has been understood theoretically for decades. But exciton movement within ...

Patent talk: Google sharpens contact lens vision

(Phys.org) —A report from Patent Bolt brings us one step closer to what Google may have in mind in developing smart contact lenses. According to the discussion Google is interested in the concept of contact ...

Warm US West, cold East: A 4,000-year pattern

Last winter's curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East. A University of Utah-led study shows that pattern became more pronounced 4,000 years ago, ...

Tech giants look to skies to spread Internet

The shortest path to the Internet for some remote corners of the world may be through the skies. That is the message from US tech giants seeking to spread the online gospel to hard-to-reach regions.