April 12, 1999
NASA planning next generation of plutonium-powered spacecraft; opponents also forming ranksBy Robyn Suriano
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CAPE CANAVERAL, Fla. - From the fiery sun to frigid Pluto, NASA plans to traverse the extremes of the solar system in the new century with missions that will tell use more about our celestial neighborhood.
But to get there, the agency will have to rely on a controversial fuel - radioactive plutonium.
Used to make electricity for science instruments on the spacecraft, NASA says the material is the only power source possible on such deep space missions.
Nonetheless, anti-nuclear foes are already opposing the flights even though NASA says new technology will greatly reduce the amount of plutonium that will be needed.
The critics worry the plutonium could be released during launch accidents and spread cancer-causing dust.
"This is clearly a sign that they are trying to minimize the risk and minimize the opposition, and in both cases they've failed miserably," said Bruce Gagnon, director of the Global Network Against Weapons and Nuclear Power in Space.
NASA strongly maintains danger to the public is remote, and says the attacks are nothing more than scare tactics.
"Plutonium can be used safely in space and it has been used safely in space for many years," said Steve Edberg, a scientist on NASA's Cassini mission to Saturn, the most recent to use plutonium.
"Obviously, NASA people live on Earth, too, so we want to ensure that everything is safe for our families and for everybody else as well."
The use of plutonium in space dates to the 1960s.
It has been flown on 27 missions, from powering experiments that the Apollo astronauts left on the moon to acting as "heating blankets" for robots working on the surface of Mars.
Mostly, it has fueled a number of remarkable spacecraft that have revolutionized our understanding of the solar system and the planets within it.
The spacecraft include:
NASA officials say such craft need plutonium because they travel too far from the sun for solar panels - which convert the sun's rays into electricity - to be practical.
- Two Pioneer probes that became the first to successfully traverse the rocky asteroid belt between Jupiter and Mars, and are now on an endless journey toward interstellar space.
- The twin Voyager spacecraft that made the historic first reconnaissance of the solar system, getting stunning looks at Jupiter, Saturn and Uranus.
- NASA's Galileo probe, which is currently studying Jupiter and has found evidence of a liquid ocean that may contain life under the icy surface of the Jovian moon Europa.
That was the case in late 1997 when NASA launched Cassini, the most recent nuclear-powered probe.
The spacecraft needed a record 72 pounds of plutonium to make electricity for its mission to Saturn some 800 million miles from the sun.
The flight generated considerable controversy before its launch on an Air Force Titan rocket from Cape Canaveral Air Station.
Nuclear opponents worldwide protested Cassini by holding rallies, circulating petitions and even lobbying the United Nations to stop the mission.
They staged a protest at Cape Canaveral a few weeks before the flight that resulted in 27 arrests when people illegally scaled the air station's gates in planned acts of civil disobedience.
The protests failed to halt the mission, which was launched safely. But opponents now are rallying against the spacecraft's planned pass near Earth on Aug. 18.
By swinging near the planet, Cassini will use Earth's gravity to gain momentum and whip it toward Saturn, where it is to arrive in 2004. NASA has been doing these "planetary flybys" for decades without problem.
However, opponents worry the spacecraft could go awry, crash into Earth's atmosphere and potentially expose billions of people to cancer-causing plutonium.
While saying that is very unlikely - the chances of such a failure are less than 1 in 1 million - NASA officials concede plutonium is a hard sell to the public.
That's why experts began searching for ways to cut back on the material long before Cassini.
The potential answer comes from a new technology called "advanced radioisotope power systems," which is NASA jargon for small generators that turn heat from decaying plutonium into electricity.
NASA has used that same process on all previous deep-space missions, but the new system will work much more efficiently.
As a result, a spacecraft can use much less plutonium than before. Instead of Cassini's 72 pounds, future craft will carry about 10 pounds of the material, NASA experts say.
The technology is being developed by Lockheed Martin under the direction of the U.S. Department of Energy.
DOE officials say they will have the first models ready for flight in late 2003. It will cost $75 million to develop the technology and build five units - four for flight and one spare.
However, the advances are not quelling concerns from anti-nuclear activists, who believe any amount of plutonium in space is unacceptable.
For instance, Gagnon and others believe solar power could be used on deep- space missions if NASA spent the time and money improving the technology - a contention NASA says is not ture.
Critics also say the risk of even tiny amounts of plutonium are severe. Studies have shown a single particle - inhaled and lodged in a person's lungs - can lead to cancer over time.
"The opposition is really really growing on a global scale, and I think that as they continually rush headlong into this stuff they're just going to help us organize," Gagnon said.
But NASA officials insist there is little chance the plutonium on their spacecraft would be pulverized into the dust that would be dangerous to people.
That's because the material is packed inside protective canisters that have been proved to withstand most launch accidents and even accidental re-entries through Earth's atmosphere.
The packaging won't change in the new system, leaving the radioactive material encased in super-strong, multi-layered devices.
"The plutonium is housed in modules that have been rigorously tested for previous missions," said Lisa Herrera, the DOE's program manager for the new system.
With the new technology and old safety measures in place, NASA plans to mount at least three missions early in 21st century that will use plutonium for power.
All the missions still are under study, and officials can't say precisely how much plutonium would be needed to fuel them until the design of each spacecraft is finished.
- Europa Orbiter, which is scheduled for launch in 2003 to further explore the possibility of whether an ocean exists under the moon's ice cap. It would arrive at Europa in 2007.
- Pluto-Kuiper Express would follow in 2004 on the first investigation of the most distant planet in our solar system. The spacecraft would arrive at Pluto in 2012 for a study of the planet and its moon, Charon.
- Solar Probe would be the last of the trio. Launched in 2007, it would dive inside the sun's outer layer - or corona - in 2010 to learn more our life-giving star.
However, they estimate it will be significantly less than the 72 pounds flown on Cassini.
"We don't envision that we're going to be using that much plutonium again," said Dave Lavery, NASA's program executive for solar and planetary exploration at NASA headquarters in Washington, D.C..
"But... we still don't have an alternative that can power a spacecraft at those sort of environments."
Added John McNamee, NASA's project manager for the three flights at NASA's Jet Propulsion Laboratory in Pasadena, Calif.:
"At this stage, there is not a viable alternative to plutonium. There have been many studies that suggest, theoretically, they could be done with solar power, but it's just not practical. "
Posted: 4/14/99 9:43:50 AM