Dave Atkinson has a lot to be anxious about.
The University of Idaho researcher has years of work riding on a rocket next week as the $3.4 billion Cassini spacecraft lifts off for Saturn. The craft will have to negotiate the hazards of the launch, close passes by Venus, Earth and Jupiter, then the delicate act of riding a probe onto the planet’s largest moon at 13,000 mph.
The seven-year trip will be like waiting for Christmas and a newborn at the same time.
“You go through this long labor,” Atkinson said, “and then you finally get up to the end and say, ‘Is it going to work, is everything going to be OK?”’
Then there’s the plutonium.
Cassini will get heat and electric power from 72 pounds of highly radioactive plutonium 238, more than has ever been carried into space. The National Aeronautics and Space Administration says the risk to the public is minimal. Anti-nuclear protesters and some experts say the space agency is miscalculating a risk they say is not worth taking.
Hundreds of protesters have marched on Cape Canaveral, where liftoff is scheduled for Monday morning. NASA and the anti-Cassini forces have taken to a heated public debate that includes dueling Web sites. The Stop Cassini Site calls itself “perhaps the world’s most controversial Web site ever!”
And Atkinson, an electrical engineer by trade, is finding himself talking more and more about decay rates and millirems. He was scheduled to spend three days this week talking to Florida school groups about the mission itself, but NASA, growing shy about the plutonium issue, canceled his plans.
“I think everybody involved with the mission is nervous, and they’re worried about what could possibly happen,” Atkinson, 41, said. “But at the same time I think what’s really scary to a lot of us is the fact that most of the information that is being passed along is misinformation. … It’s not really the correct information on which to base a decision.”
The debate is certainly obscuring the magnitude of the mission itself.
Two stories tall and weighing more than 2 tons, Cassini will gather some 300,000 images and enough data to fill 416 compact discs with information on Saturn’s rings, chemistry, dust and more. On the Huygens probe will be the European Spage Agency’s Doppler wind experiment - Atkinson’s project - which will measure wind speeds on the moon Titan by analyzing the rate at which radio signals change during the probe’s descent.
Titan has the only other nitrogen atmosphere in the solar system, offering a glimpse of conditions on Earth hundreds of millions of years ago.
“We don’t really have much idea of what Earth looked like just before life started,” Atkinson said. “With Titan we might start getting some answers. It’s an amazing place.”
Combined with what science knows about other moons and planets, Titan can also serve as an outsized laboratory for studying the way wind works.
“What we learn about the winds of Titan in and of themselves may not be of tremendous value,” Atkinson said, “but when you start comparing the winds of Titan to the winds of Venus, to the winds of Mars and Jupiter and Saturn, you start to ask, ‘Why are they different and how are they the same, and how do they compare to the Earth?’ We start learning an awful lot about why things are the way they are.”
But plutonium in the Earth’s atmosphere is proving to be a more pressing concern than the wind on a moon 800 million miles away.
Alan Kohn, former emergency officer for the plutonium-powered Galileo mission, has said the cancer risk posed by so much plutonium makes the project “criminally insane.”
Plutonium 238’s lifespan is much shorter than that of weapons-grade plutonium 239, but it is 270 times more radioactive, said Arjun Makhijani, head of the nonprofit Institute for Energy and Environmental Research and co-author of “Plutonium: Deadly Gold of the Nuclear Age.”
In the event of a launch accident, he said, “plutonium damage locally could be severe. And then there’s the problem of cleanup in a high-value real estate area. … I don’t know if they have assessed this.”
Speaking from his office in Takoma Park, Md., Makhijani said, “I personally think the benefit of peeking into Saturn could be achieved with healthier power modules,” Makhijani said, “and it would also be more beneficial to the rest of the economy if NASA had focussed on getting better power sources for Cassini.”
NASA said the Cassini spacecraft is traveling too far from the sun to use solar panels installed on other space missions.
Meanwhile, NASA puts the odds of a serious accident at one in 1,400 at launch and one in 476 during orbit. The agency’s odds on an accident while swinging back past the Earth after circling the sun are one in a million.
Protesters are particularly concerned about the so-called gravity assist, which will use the Earth’s gravity in 1999 to reach a speed of 42,000 mph. If something goes wrong, a combination of pressure, shrapnel and explosive forces could breach the ceramic- and iridium-encased batteries and vaporize their plutonium into the atmosphere, said Michio Kaku, a professor of nuclear physics at City University of New York.
Kaku figures 200,000 deaths could result.
NASA put the number of fatalities from a “maximum credible accident” at 2,300, then lowered it to 120.
The agency also invokes the memory of Carl Sagan, posting on its web site Sagan’s defense of using plutonium on the Galileo mission. A nuclear demonstrator himself, the astronomer agonized over the odds of the mission’s 48 pounds of plutonium being scattered around the Earth. On balance, he said, society’s energies would be better directed at the risks posed by “nuclear war (accidental and deliberate), greenhouse warming, depletion of the ozone layer, AIDS, social and economic injustice and the world population crisis.”
Atkinson uses a different analogy.
“The chances of an asteroid or a comet hitting the Earth and wiping out a billion people,” he said, “are greater than the chances of someone being injured by plutonium.” , DataTimes ILLUSTRATION: Color Photo; Graphic: Is Cassini safe?