Bombarded by ominous talk of widespread radioactive contamination after the Chernobyl nuclear disaster in the U.S.S.R., Americans are anxious about the prospect of future catastrophes closer to home. The concern is particularly acute following the Challenger tragedy and the failure of two unmanned U.S. rockets. Are the marvels of modern technology really under control? "We have been mortgaging our future, " argues Pulitzer-prizewinning astronomer Carl Sagan, 51, "and giving our children and grandchildren problems of enormously formidable difficulty. " At home in Ithaca, N. Y., with his wife, author and TV producer Ann Druyan, 36, and their daughter, Alexandra, 3, Sagan discussed the current spate of technological accidents with Assistant Editor David Grogan.

What does the Chernobyl disaster tell us about man's relationship to technology?

Chernobyl is the latest example of our technological overconfidence, as well as our unwillingness to make tough decisions now to avoid future catastrophes. We live as though there's no tomorrow. Like the Challenger disaster, Bhopal and Three Mile Island, Chernobyl indicates that in dealing with complex technological systems, we are not always in control. What is more disturbing is that there is no systematic effort to try to anticipate the global dangers of our technology. Faced with political and economic pressures to cut costs or meet unrealistic time deadlines, people tend to simply cross their fingers and hope that no safety issues will come up when they are in charge.

Does Chernobyl tell us anything about the U.S. nuclear power industry?

Soviet technological leaders proudly proclaimed that you would have to wait 10,000 years before there was a possibility of a serious accident in the Chernobyl plant. Yet despite the best combination of technical and political judgment, disaster struck.

In the U.S., people in the nuclear power industry have a vested interest in giving bland assurances, despite the experience of Three Mile Island, that the same thing could not happen here. But the clearest indication that things are not safe is that since 1979 there have been no new construction permits issued for nuclear power plants. That's because the people may understand the safety issues better than the plant operators.

Is nuclear power so intrinsically dangerous that its use should now be completely suspended?

What must not be forgotten is that the alternatives are also dangerous. One of the reasons for nuclear power plants is that they lessen our reliance on fossil fuels, which release carbon dioxide into the atmosphere when burned. Carbon dioxide impedes infrared rays from being radiated out into space, which causes a long-term warming of the atmosphere now called the Greenhouse Effect. At present rates of usage of coal, oil and natural gas, the Greenhouse Effect will lead to a significant global climatic catastrophe by the late 21st century.

We must stop squandering the energy supplies we do have. In general we need to overcome the scandalous tendency to ignore the long-term consequences of major technological endeavors. In this context much safer fission power plants might be looked on as a stopgap measure between the use of fossil fuels and some safer form of energy like solar or fusion power.

Is the U.S. less vulnerable than the Soviet Union to such catastrophes as Chernobyl because of greater public accountability here?

Certainly when there are more people worrying about potential catastrophes, it is more likely that you can avoid them. If nobody in the Soviet Union is allowed to think about issues of safety except a very small group of politically reliable apparatchiks, then of course it is much more dangerous. But the same danger exists in the United States when information is held behind classification barriers. In the nuclear weapons business, you have to be a select member of the club to look into the effectiveness of a "permissive action link," or PAL, which is the machinery designed to prevent the accidental or unauthorized use of a nuclear weapon. The public has no way to check.

The sad truth is that all governments lie through their teeth. Try to find out what the public health statistics are in French Polynesia, where France has tested nuclear weapons for 20 years. Of all the areas under French control, it is the only place where the data is unavailable. Are people dying of radiation sickness there? The French have gone to such extremes in maintaining their unlimited privileges to test nuclear weapons in the Pacific that, when challenged by Greenpeace, they sent scuba diving commandos to the most crowded harbor in New Zealand to blow up the small Greenpeace vessel Rainbow Warrior, killing one of its crew members.

Many Americans seem to believe that sooner or later technology can solve all of our problems. Is this mode of thinking a problem in itself?

Certainly there is something appealing about the idea of a pure technological fix, because it doesn't demand very much of us emotionally. This is exactly the state of mind that led the Reagan Administration to conclude that Star Wars, or the Strategic Defense Initiative, could be the answer to nuclear war. Star Wars embodies all the technological problems we have been talking about, but in spades. You have to have extremely high confidence in the technology if you are willing to turn over the safety of the world, which is after all what we are talking about, to a system designed to shoot down all the warheads in an attack by one of the superpowers against the other. And when you wave a trillion dollars, which is what an effective Star Wars system would cost, at the U.S. aerospace industry, you are bound to create a kind of juggernaut. A trillion dollars—half the national debt—creates what I call the Bamboozle Effect: If you are bamboozled long enough, it is too painful to admit you have made a mistake. But even enthusiastic supporters of Star Wars estimate that it could destroy at most 50 to 90 percent of the present Soviet strategic arsenal, which would still leave them with 1,000 to 5,000 strategic warheads penetrating U.S. defenses—more than enough to obliterate the U.S. as a political entity.

Beyond this, the Soviets might simply rely more on cruise missiles or small aircraft, which could go completely undetected by Star Wars. Nuclear weapons also can be sent in diplomatic pouches. For all we know, right now there may be a dozen nuclear weapons in Washington—or Moscow—in embassy basements.

Considering the dangers we have been discussing, how do we go about controlling sophisticated technologies?

The first thing we need to do is admit our fallibility. We need to eat a little humble pie. One step in the right direction would be for every country to establish a first-rate institute whose job would be to look at the global consequences of technology. Still more difficult, but absolutely essential, is a coming together of the nations of the world to realize we have one small and fragile planet that we all share collectively, and that we will survive only if we work together.

Are you optimistic about the future?

As a scientist, I see through space technology an aperture to a very desirable future. Just think of what we are doing. We have four spacecraft that are leaving the solar system bound for the stars. We have landed on the planet Mars. It is astonishing. And yet there has never been better reason for nervousness because the same technology—rocketry—can be used to send nuclear weapons halfway around the planet. It's a kind of classic morality play. You can imagine God saying, "I set before you this power. You can use it to destroy yourselves or to take you to the stars. It's up to you."