TCS Daily


NASA Goes Nuclear

By Kenneth Silber - February 26, 2002 12:00 AM

Do you remember the tragedy of August 1999, when the Cassini space probe veered off course on its way to Saturn, crashed into Earth and scattered plutonium over millions of terrified people?

You probably don't remember, because it never happened. But this wildly overstated scenario was a staple of the late-1990s protest movement against the Cassini mission. Antinuclear activists denounced the spacecraft's use of plutonium-powered electricity generators as, in the words of journalism professor and protest leader Karl Grossman, "a holocaust in the making." Actually, the chances of Cassini crashing as it passed by our planet were less than one in a million, and the radiation released in this improbable event would have been far less than what people are normally exposed to from cosmic rays, radon and other sources. As for the activists' other supposedly catastrophic scenario - the danger of an explosion on launch - this likely would have released no radiation at all.

Cassini is now cruising beyond Jupiter, but we can expect a new upsurge in activism against "nukes in space." That's because NASA has just announced a major push to develop nuclear energy for spacecraft. The agency's proposed 2003 budget, unveiled in early February, includes $125 million for the first part of a five-year, $950 million Nuclear Systems Initiative that would aim at building both nuclear-electric rockets and (as on Cassini) devices that convert radioactive heat into electricity for instruments.

This initiative could give a powerful, wide-ranging boost to space exploration. Nuclear rockets could cut years off the journeys of robotic probes to the outer solar system - and halve the time for human trips to Mars, thus minimizing such problems as the physical debility caused by prolonged weightlessness. Nuclear generators will allow instruments to operate far from the sun, and vastly increase the capabilities of devices on Mars. Consider: NASA is replacing a planned solar rover for Mars with a nuclear rover that will roam up to 50 miles over 1,000 days - rather than one or two miles over 180 days.

Moreover, such things can be done safely. Elaborate measures are taken to minimize the risks in current space missions. The plutonium in probes such as Cassini is shielded by high-strength graphite and heat-resistant iridium, and is stored in a ceramic form that is extremely difficult to vaporize. Even more stringent precautions might be employed on future space missions. Nuclear reactors, for instance, could be sent into space "cold," incapable of operation until their carrying craft are far removed from Earth.

The nuclear program, which will be considered by Congress over the coming months, marks a major shift for NASA under its new, Bush-appointed administrator, Sean O'Keefe. The agency had not made a serious effort to develop nuclear rockets since the early 1970s, when its NERVA project (Nuclear Engine for Rocket Vehicle Applications) was cancelled in the budget cuts that followed the successful Apollo moon missions.

In recent decades, NASA's nuclear ambitions have focused on the more modest project of building radioisotope thermoelectric generators, or RTGs, to provide a power supply for instruments. Some 20 space missions have used such generators; Cassini carries three RTGs, and the Galileo probe to Jupiter has two. But even here, the space agency's efforts have been flagging. NASA reports that it currently has only one RTG in its inventory.

The long malaise in space nuclear power owes much to the controversy and public wariness that attends any use of nuclear energy. The Galileo and Cassini missions both sparked protests from groups such as Food Not Bombs and the Florida Coalition for Peace and Justice, and NASA's new initiative has already begun to draw fire. It remains to be seen whether opposition will spread beyond relatively obscure parts of the antinuclear and environmental left. In the past, major environmental organizations showed little interest in opposing space nuclear power - but there was fairly limited activity to oppose.

Opponents have tended to focus - ludicrously - not only on the technology's safety but also on its supposed military implications. Bruce Gagnon of the Florida-based Global Network Against Weapons and Nuclear Power in Space, told the Los Angeles Times this month: "It's our position that just like missile defense is a Trojan horse for the Pentagon's real agenda for domination of space, NASA's nuclear rocket is a Trojan horse for militarization of space." During the anti-Cassini campaign, physicist Michio Kaku warned that the Saturn probe was a step toward "nuclear-powered battle stations in outer space."

In reality, the main thrust of space nuclear technology is its ability to operate far from both Earth and the sun. Cassini's generators produce only 800 watts of electricity - less than what's used by a dozen light bulbs - but will do so over a 12-year mission in deep space. Nuclear rockets, once they are developed, would only marginally cut down on flight time to, say, Baghdad, but are enormously helpful if one is traveling to Pluto. If the military is behind NASA's nuclear initiative, then the enemy must be extraterrestrial.
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