Saturnian odyssey

Space

Saturnian odyssey


Ringside view:  One of Saturn's moons, Mimas, casts a long, dark shadow across the planet's rings. (NASA/JPL/Space Science Institute via The New York Times)

It is twilight time on Saturn. Shadows lengthened to stretch thousands of miles across the planet’s famous rings this summer as they slowly tilted edge-on to the Sun, which they do every 15 years, casting into sharp relief every bump and wiggle and warp in the buttery and wafer-thin bands that are the solar system’s most popular scenic attraction.

From her metaphorical perch on the bridge of the Cassini spacecraft, which has been orbiting Saturn for five years, Carolyn Porco, who heads the camera team, is ecstatic about the view.

“It’s another one of those things that make you pinch yourself and say, “Boy am I lucky to be around now,” Porco said. “For the first time in 400 years, we’re seeing Saturn’s rings in three dimensions.”

A grand view of the rings

Porco and the Cassini team have just released a grand view of the rings in all their shadowed glory, including clumps, spikes, undulations and waves two-and-a-half miles high on the edge of one ring.

“We always knew it would be good; instead, it’s been extraordinary,” Porco said of the cascade of results that have placed her in a spotlight to which she has become increasingly accustomed. “I feel I’m on a great human adventure,” she said.

The work may be carried out by robots, Porco said, “but we are all explorers.” “It’s thrilling,” she added, "and I want everyone to know how thrilling it is.”

Porco, 56, a senior researcher at the Space Science Institute in Boulder, Colo., may be the leader of the camera team on the $3.4 billion Cassini mission, an adjunct professor at the University of Colorado and one of Wired magazine’s 15 people who should be advising the president. Her entries on the Cassini imaging website echo the spirit of the character Capt. James T Kirk on Star Trek:

Captain’s Log
March 23, 2009

“We are almost there. Saturn and we, its companions, have journeyed together now for nearly five years, in a circumnavigation of the outer solar system.”

As a graduate student at the California Institute of Technology, Porco floundered at first but then got a job helping to analyse data from the two Voyager spacecraft, which toured the outer planets from Jupiter to Neptune from 1978 to 1989.

It was there, said Peter Goldreich, her thesis advisor, that she discovered that the mysterious dark spokes in Saturn’s ring system were connected to the planet’s magnetic field. She completed her thesis on aspects of the rings and how they were shaped by the gravity of tiny moonlets.

By the time Voyager passed Neptune in 1989, Porco was a research associate at the University of Arizona and leading a small team trying to make sense of the thin rings around Neptune. Voyager, Porco said, was the time of her life. “It had all the elements of Homeric legend,” she said. “It was a long 12-year odyssey, punctuated by brief episodes of great discovery and conquest. And then it was back in the boat, oars in the water, until years later we reached our next port of call. It was a defining experience for many of us, and certainly for me.”

Privileged spot

The chance to channel Porco’s inner Cap. Kirk continued with the $3.4 billion Cassini mission, which was launched on a roundabout course toward Saturn in 1997 and arrived in 2004. Being on the imaging team is like standing on the bridge of the spaceship, she said. “We have the windows,” she said. “That’s what we’re responsible for.”

Porco was chosen over more senior astronomers to head the Cassini camera team in 1990, one of 12 team leaders for the spacecraft. The job swallowed her life, she said, and required her hard-won toughness. “Our experiment has been spectacularly successful,” she said, “and that would never have happened if I let people roll over me.” One of the most thrilling Cassini moments was in 2004 when the Huygens probe detached from Cassini and landed on Saturn’s largest moon, Titan, a strange, frigid world where rocks are made of ice, and rivers and oceans are formed of what Porco has described as “paint thinner.”

Last month, astronomers announced that they had detected methane storms on Titan, a cloudy moon that has an atmosphere denser than that of Earth.

They also discovered plumes erupting from the south pole of another Saturn moon, Enceladus, suggesting the presence of underground water and prompting talk about a future mission to cruise through the plumes. “Should we ever discover that life has arisen twice,” Porco said, “that would be a game-changer.”

The Titan landing, Porco said in a talk in 2007 should have been celebrated with parades in every major city.

That talk led to another movie adventure. J J Abrams, the producer of the television series Lost, was listening and asked Porco to consult on his Star Trek movie. On a visit to the set, she suggested that a scene in which the Starship Enterprise materialised inside clouds be set on Titan.

In an interview, Abrams said: “She helped us feel connected to what Gene Roddenberry had been trying to do. This is our future,” referring to the creator of Star Trek. Cassini endures, and Porco is a member of the team for the New Horizons spacecraft, scheduled to arrive at Pluto in 2015. But she said she hoped to spend more of her time popularising science and hopes to write a book about Cassini.

“To my mind,” Porco said, “most people go through life recoiling from its best parts. They miss the enrichment that just a basic knowledge of the physical world can bring to the most ordinary experiences. It’s like there’s a pulsating, hidden world, governed by ancient laws and principles, underlying everything around us, from the movements of electrical charges to the motions of the planets, and most people are completely unaware of it. “To me, that’s a shame.”

* Carolyn Porco heads the camera team on the Cassini mission and got to see Saturn’s rings in three dimensions.

* One of the most thrilling Cassini moments was in 2004 when the Huygens probe detached from Cassini.

* Recently, astronomers announced that they had detected methane storms on Titan, a cloudy moon with a denser atmosphere than the Earth.

NYT News Service

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