Cassini launches familiar debate Nuclear foes fear accidents, but NASA insists risk is tiny

October 12, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

With NASA's 6-ton Cassini spacecraft cleared for launch tomorrow on a 6 1/2 -year voyage to Saturn, space agency scientists and anti-nuclear activists have converged on Cape Canaveral, Fla., with their fingers crossed.

The NASA folks are hoping the $3.4 billion mission will lift off without a hugely expensive scientific failure.

Nuclear protesters, meanwhile, are praying that Cassini's electric generators, powered by 72 pounds of plutonium, will not be blown apart in a launch accident that showers radiation over Central Florida, or vaporized later in a fiery re-entry that poisons the atmosphere and puts hundreds of thousands of lives in danger.

NASA insists the risk of such accidents is tiny, and Cassini's potential scientific payoff is worth it.

"I'm taking my wife and youngest daughter and three of my grandkids" to the launch, said Dr. Ellis Miner, Cassini science manager for NASA's Jet Propulsion Laboratory. "If I had any concerns at all, I certainly would not take them along."

Cassini's opponents remember the Titanic. "Nothing humans have ever made has been indestructible," said Bruce Gagnon, coordinator for the Florida Coalition for Peace and Justice, representing church and peace groups.

Gagnon also fears a nuclearization of space, orchestrated by post-Cold-Warriors in the military, weapons labs and academia. Next, he said, they will try to launch nuclear reactors to power moon and Mars bases, and powerful space weapons.

Others just see unnecessary risk. "For pocket change you can downsize it" and go later with solar power, said Dr. Michio Kaku, a professor of theoretical physics at the City University of New York. "Saturn will still be there."

It's a familiar confrontation.

Anti-nuclear groups went to federal court in 1989 and 1990 and tried unsuccessfully to block the launches of the Galileo mission to Jupiter and the Ulysses solar explorer. Both carried plutonium-powered generators like Cassini's.

In fact, these "radioisotope thermoelectric generators," or RTGs, have flown on 23 previous U.S. spacecraft. They were aboard the Apollo lunar landers; the twin Viking Mars landers in 1976; the two Voyager spacecraft that surveyed the planets in the 1980s; weather and spy satellites.

What's new is that Cassini is carrying 72 pounds of plutonium, 22 more than Galileo and the most ever launched at one time. To power its big scientific payload at Saturn, 887 million miles from the sun, Cassini would need solar panels the size of two tennis courts -- too heavy to launch and too big to maneuver in space.

The generators are a reliable alternative, NASA argues. The two Voyager RTGs are still working 20 years after launch and more than 5 billion miles from the sun.

Even the late Dr. Carl Sagan -- a well-known planetary scientist who demonstrated against nuclear weapons testing and warned the deadly "nuclear winter" that would follow an atomic war -- concluded after considerable "agonizing" that RTGs posed an acceptable nuclear risk.

Even taking into account "the past history of government incompetence or worse in matters of public health," Sagan wrote during the Galileo debate in 1989, "my personal vote is to launch."

Saturn, NASA's Miner said, is "probably the richest scientific target we have available anywhere in our solar system."

It tantalizes with its extensive ring system and a wider variety of moons than any other planet. One of those 18 moons, Titan, sports a thick nitrogen atmosphere and hints of a deep ocean of liquid methane -- the only place in the solar system besides Earth with air and ocean.

"Titan may be a sort of Earth in deep freeze," Miner said. "That aspect makes it an exciting place to go." While Cassini orbits Saturn, its 771-pound Huygens probe will parachute to a soft landing (or splashdown) on Titan.

Eager scientists packed 18 instruments onto Cassini, making the two-story craft NASA's biggest planetary mission. Only the Soviet Union's twin Phobos Mars explorers, launched in 1988, weighed more.

Born big in 1989, Cassini survived cancellation attempts by Congress and NASA Administrator Daniel S. Goldin. But it is the last of its breed.

The new mantra for space science is "better, cheaper, faster." Goldin wants mini-spacecraft that can be developed quickly for a few hundred million dollars, with a swift scientific return. The new generation includes the Mars Pathfinder that landed in July.

Critics blame Cassini's size and thirst for electricity for the decision to power it with plutonium.

"This is a gas-guzzling Cadillac with tail fins," said Kaku. "I would send two compacts to Saturn rather than one gas-guzzler that uses plutonium."

Worldwide opposition

Opponents around the world have demonstrated and sent petitions and letters to President Clinton. Many people have encountered the issue on the Internet.

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