CHAPTER 13: ASTEROID DEFENSES

In the months following the Los Alamos meeting, the astronomers and the weapons builders continued their dialogue. In time, both the United States Air Force and the Russian nuclear establishment became interested, as we describe in this chapter. An influential participant in all these discussions was Edward Teller, who had adopted the asteroid defense issue as a major theme for international cooperation in the post-cold-war world.

At Los Alamos, Teller had followed Lowell Wood's lead and focused on the problem of defending against small asteroids, which could not be detected more than a few days in advance of their collision with the Earth. This concept led to a "shoot first" defense strategy centered on a fleet of nuclear-tipped anti-asteroid missiles held at the ready. However, Teller's attitudes soon began to evolve. Later in the spring of 1992, when he and Morrison gave back-to-back keynote lectures at a meeting of the National Space Society in Colorado Springs, Teller had accepted the argument that small projectiles were not a problem and that some sort of comprehensive asteroid survey should be carried out. At that time, however, he advocated conducting a space-based search for NEOs using Star Wars technology. A series of small satellites would be placed in Earth orbit to scan the sky for asteroids, transmitting their observations to the ground to analysis.

Teller's primary argument for a space-based NEO search was that serendipitous astronomical discoveries might result from wide-field space telescopes. At Colorado Springs, Morrison countered that a ground-based search was much cheaper and more cost-effective: the job could be done for a hundred million dollars from the ground rather but would cost more than a billion dollars from space. At that meeting, the two could only agree to disagree. But by the time of the next hazard meeting, in January 1993, Teller was apparently reconciled to the cost-effectiveness of a ground-based asteroid survey like Spaceguard.

Looking ahead to the problems of deflection, however, Teller expressed concern about our lack of knowledge of the physical properties of comets and asteroids. Such knowledge would be necessary if we were to plan a comprehensive defense. He pushed for a major program of spacecraft visits to explore the comets and asteroids, using small and relatively inexpensive probes based on the "brilliant eyes" surveillance system being proposed by Wood at Livermore. He also suggested that initial spacecraft visits should be followed by active testing, including the experimental deflection of asteroids and comets to develop the technology that might someday be needed for defense against a real impact threat. Teller's proposal to start nuking asteroids stimulated a strong response from Carl Sagan and other astronomers, which we will discuss in a later chapter.

Although he remained in the background during the early interactions between astronomers and weapons scientists, one of the most influential figures in the impact hazard debates was Col. Pete Worden of the U.S. Air Force. A handsome career military officer with a Ph.D. in astrophysics, Worden was a long-time "space cadet". A severe critic of NASA, which he viewed as technically timid and excessively bureaucratic, Worden had embraced Reagan's Star Wars program as a means to develop new space technology and perhaps, if NASA faltered, to create the basis for an alternative space exploration program. Having served on the staff of the National Space Council under Vice President Quayle, in 1992 he was in the Pentagon managing advanced technology for the Star Wars program. There his small cadre of Air Force enthusiasts sometimes called themselves the "space Nazis".

With Teller's support, Pete Worden decided to organize another conference on asteroid defenses for the spring of 1993. This meeting would be everything that Rather's Los Alamos conference should have been. Focusing on near-term issues, Worden's meeting would exclude the fringe elements and their impractical "new technology" schemes. His meeting would be international, with the participation of leaders from the Russian defense establishment. And far from banning the press, Worden invited not only science reporters but also leading critics of the Star Wars program from a number of Washington space and peace advocacy groups. Bringing together 50 of the leading astronomers, weapons scientists, and their critics in an environment conducive to open discussion and compromise, Worden sought to forge a consensus in support of asteroid defense. For a location, he chose the picturesque town of Erice, perched atop a mountain on the west coast of Sicily. We both attended.

Erice, an ancient walled hill-town with narrow cobbled streets and glorious views of the Mediterranean, was developed in the 1970s as a site for international science conferences and summer courses, complete with modern meeting facilities, classrooms, and dormitories, all constructed in the renovated interiors of ancient monasteries. Erice was well known to Teller, Worden, and other insiders of the U.S. defense establishment. A series of annual "Seminars on Nuclear War" held there had provided opportunities for high-level military and civilian defense strategists from the U.S. and the Soviet Union to exchange views on a regular basis. With the end of the Cold War, these seminars had been broadened and retitled as "Seminars on Planetary Emergencies". The subject of Worden's Erice seminar in May 1993 was "The Impact on Earth of an Asteroid or Comet".

Worden set the tone for the meeting in his introductory talk, expressing hope for a consensus based on recognition of the reality of the impact hazard and a commitment for an international effort to deal with it, initially through support for the Spaceguard Survey. When we reported our work on the nature of the risk, emphasizing asteroids 1 km or more in diameter, we found none of the hostility that had characterized Los Alamos. The discussions were constructive, and gradually agreement emerged among the participants, in spite of their different backgrounds. The Russians seemed especially anxious to share their decades of experience with nuclear weapons in the service of a new, international cause.

On the final day of the Erice conference, we all gathered in the main monastery building to agree upon a statement that summarized the conclusions we had reached. The first four points of the statement were relatively straightforward. The group agreed that "cosmic impact is an environmentally significant phenomenon which has played a major role in the evolution of life on Earth", and that "the threat is real and requires further internationally coordinated public education efforts." They also agreed that "gathering of additional physical knowledge of NEOs and their effect on the Earth is a scientifically and socially important endeavor," and that "dedicated international astronomical facilities similar to the proposed Spaceguard System should be developed."

On a final question, however, consensus broke down. Worden did not want to include any discussion of defense systems, but Teller insisted that this issue be addressed. Teller was convinced that nuclear experiments on deflecting real asteroids and comets were necessary. He had two reasons. One was technical: the need to learn how to accomplish such a task in advance of any actual emergency. His second reason was political. He argued that it would be extremely difficult to obtain international agreement for any use of nuclear devices in space, and that we had better start now to work out ways to deal with this problem. Teller considered the social experiment of forging international consensus in support of experimental deflections to be more challenging than the technical problems of accomplishing the deflection once it was approved.

In the Erice environment, Teller did not automatically get his way. Opposed by Worden, Shoemaker, and all of the Spaceguard astronomers attending the conference, Teller found himself engaged in a real debate. Most of us wanted to say explicitly that we did not favor experimentation at this time, but Teller stood his ground. He would not agree to any statement that called for deferring experiments. The majority would not sign any statement that endorsed such experiments. After heated arguments, the stalemate was resolved in the waning minutes of the conference and compromise wording was reluctantly approved: "The study of potential mitigation systems should be continued. Many of us believe that unless a specific and imminent threat becomes obvious, actual construction and testing of systems that might have the potential to deflect or mitigate a threat may be deferred because technology systems will improve." The "many" referred to in the statement was nearly everyone at the meeting except Teller.

In spite of this last-minute dispute, Pete Worden had accomplished his goal. Everyone at last agreed on the general nature of the impact threat. The Russian attendees were enthusiastic about joint efforts that might make use of their capabilities, including unused tracking telescopes that they had available. And, perhaps most remarkable, all of the critics who attended were now converts and supporters of continued efforts to deal with the impact threat.

Science is founded on the principle that observations, experiments, and calculations can be reproduced and verified. The conclusions of an individual scientist or a team should be checked through repetition by others. In practice, however, one cannot check or reproduce the vast amount of data and interpretation that are presented at meetings and published in technical journals. Individual scientists therefore develop a sense of who and what can be trusted. We learn, through a combination of experience and intuition, who are the most reliable observers, the most precise experimentalists, and the cleverest theorists. When the NASA astronomers and the physicists from the nuclear weapons labs first came together in January 1992, they had no basis for trust, no way to know who in the other camp was reliable or brilliant and who might not be. Between Los Alamos and Erice, a sort of Darwinian process eliminated the fringe elements and allowed some members from each community to gauge the worth of the others. One of the products of this interaction was a sense of trust and shared values.

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The emergence in Russia of concern about the impact hazard happened at the same time as in the United States, with Russian astronomers and weapons builders playing roles that paralleled those of their American counterparts. Many Russian scientists were interested in defense against asteroids for the same reasons as Americans: a mixture of scientific curiosity, desire to perform a socially useful purpose by promoting protection of the Earth, and self-interest associated with retaining their jobs and research funding. They sponsored the first international meeting specifically devoted to the NEO impact hazard, held in October 1991.

At just the moment the Soviet Union was disintegrating, astronomers from the Institute for Theoretical Astronomy of the USSR Academy of Sciences invited their colleagues from Russia and abroad (ourselves included) to meet in St. Petersburg (then newly renamed from Leningrad). Few of the Russian attendees were previously involved with the impact hazard, but after three days of open and vigorous discussion, they endorsed an asteroid survey. The organizers were particularly interested in making a case for Russian government funding for a new search telescope and for follow-up studies of NEO orbits, a scientific specialty of the Institute for Theoretical Astronomy. Following the meeting they formed an international organization on the impact hazard to support the legitimacy of their funding requests.

While the Russian astronomers continued to exchange information with their counterparts from the Spaceguard team in the United States, a quite different group of Russians began discussions with Teller and his colleagues from the U.S. weapons laboratories. For many years the defense strategists and weapons builders from the U.S. and Russia had worked together, first as cold-war rivals and more recently in a spirit of international cooperation. These scientists were especially interested in applying their experience with nuclear testing to problems associated with the effects of impact explosions. Since the USSR had set off much larger atmospheric tests than had the Americans, they were able to make unique contributions to this research. Within Russia the astronomers and the weapons scientists initially pursued their interests independently, but by 1994 they had begun to talk to each other, largely at the initiative of small, dapper nuclear physicist Vadim Simonenko, an energetic, outgoing leader of the new post-Soviet generation of Russian defense experts.

Simonenko worked at the Institute of Technical Physics of the Russian Federal Nuclear Center -- one of two major centers for research on nuclear weapons and the Russian equivalent of Livermore National Laboratory in the United States. For four decades the existence of this Federal Nuclear Center had been a military secret, and the city in the southern Urals where it was located did not even have a name -- just a postal code, Chelyabinsk-70. It was a major milestone in the emergence of this secret city when Simonenko obtained permission to host an international conference on asteroid defense there. The conference was named "Space Protection of the Earth 1994", and both Teller and Wood accepted invitations to attend, as did five other Americans, including Tom Gehrels and one of us (Morrison).

The American party arrived at the Ekaterinburg Airport in the small hours of the morning of September 25, having crossed 12 time zones in the flight from California. Soon we were in a bus, following the blinking blue light of a police escort through endless miles of white birch trees to our destination: a closed city that appears on no map of Russia. Only during the preceding year had it obtained a name: Snezhinsk, which means "snowy" in Russian. When we finally arrived, we entered Snezhinsk through high barbed wire fences guarded by soldiers with automatic weapons and unsheathed bayonets. Here, isolated from the rest of the world, lived the 15,000 workers at the nuclear institute and their families. A huge bronze statue of Lenin still dominated the central square, and several of us spoke with students in the schools who had never before seen or met an American. These talented people, who have spent two generations building nuclear bombs in this closed society, were looking for alternatives. Shooting down asteroids seemed like a possibility.

The Space Protection meeting was attended by about 150 Russians, the majority of whom had not previously worked with foreigners. These scientists and engineers were experts in nuclear weapons and missile systems, including space tracking and surveillance. For a week they met to discuss asteroids, with particular emphasis on schemes for interception and nuclear deflection or destruction of NEOs. Teller, as "father of the H-bomb", was idolized by the Russian nuclear community, and he and Wood had come to Russia with a message that this audience was happy to hear. The Teller-Wood thesis was simple: we must build an international defense system against cosmic impacts, and an urgent part of that effort is to conduct nuclear tests to learn how to deflect or destroy NEOs. Teller emphasized that such an experimental program was the only way to obtain the required data, and that nuking asteroids represented the most cost-effective kind of experimentation. In case anyone missed the message, Wood also told the audience that there were no international prohibitions against nuclear explosions in space, since the existing treaties dealt only with "weapons of mass destruction", not peaceful uses of nuclear explosives intended to develop a capability to protect the Earth. Teller added that only fear-mongers opposed the peaceful use of nuclear explosives.

When Tom Gehrels told the conference that the majority of American scientists opposed nuclear testing in space, he was fiercely attacked by both Teller and Wood for his efforts to "politicize" the meeting. These attacks seemed particularly inappropriate directed toward Gehrels, who had broad international experience and personal cultural ties to Europe and Asia as well as America. For good measure, Wood also publicly accused Morrison and the Spaceguard scientists of intentionally minimizing the impact risk and lying to the American Congress. Here, on Russian soil, the apparent consensus among the Americans evaporated, and Teller and Wood seemed less inhibited about their advocacy of nuclear testing in space. This was certainly a message that the Russians welcomed, desperate as they were to find a future for their nuclear profession in a world increasingly committed to disarmament and reduction in international tensions.

The Russian and American weapons builders have held two additional defense meetings after the Space Protection of the Earth 94 conference, at Livermore in 1995 and again at Snezhinsk in 1996, but these meetings were anticlimactic. Without funding, there was little technical progress on developing defense systems, only a recycling of the same ideas and proposals. In fact, not one scientist from either the Livermore or Los Alamos National Laboratories bothered to attend Simonenko's Space Protection of the Earth 96 meeting in the Urals. Meanwhile, the major Russian aerospace industries have taken up the NEO defense issue in their efforts to find new customers. The Lovochkin, Khrunichev, and Makeyav companies all made presentations at the 1996 Space Protection meeting favoring immediate deployment of a "Space Shield" defense system, based on the concepts of a short-range defense that had been discredited in the United States ever since the Los Alamos workshop in 1992. A.V. Zaitzev of Lavochkin went so far as to say that he could reveal for the first time to this audience the previously-secret development in Russia of all the elements of such a Space Shield. He said that their proposal was based on the Zenit rocket which can be readied for launch in just 90 minutes, the Mars-96 spacecraft which has the capacity to carry multi-megaton nuclear explosives, and the ASTRON space telescope which can be modified to serve as a NEO surveillance system. All this sounds pretty scary, but even the Russian scientists did not take this Space Shield proposal very seriously.

In the same week in September 1996 that the defense scientists met at Snezhinsk, world leaders at the UN signed the Comprehensive Nuclear Test Ban Treaty, adding to the Russians' desperate concern about their future in what had once been a model city, with its lovely parks and excellent schools. No one had been paid for three months, and a few days following the conference, the Director of the Federal Nuclear Center in Snezhinsk committed suicide. As we drank vodka toasts to international cooperation at the final conference banquet, flurries of snow were already falling through the birch forests, and the winter promised to be a cruel one. Whatever the future might hold for NEO defenses, these celestial threats could not solve the immediate problems of the Russian defense labs and their staffs.

In the months following the Los Alamos meeting, the astronomers and the weapons builders continued their dialogue. In time, both the United States Air Force and the Russian nuclear establishment became interested, as we describe in this chapter. A continuing influential participant in all these discussions was Edward Teller, who adopted the asteroid defense issue as a major theme for international cooperation in the post-cold-war world. We discuss how US Air Force Col. Pete Worden brought the US and Russian participants together for the first time in 1993 in an isolated monastery in Sicily, and the return invitation from the Russian nuclear scientists to meet in 1994 in the Siberian city of Chelyabinsk-70. At Chelyabinsk-70, a formerly secret city still surrounded by double barbed-wire fences patrolled by soldiers and dogs, little has changed since the Soviet era. There is even a huge bronze statue of Lenin still standing in the central square. This was the occasion of Teller's first visit to the Russian nuclear center, and we provide first-hand descriptions of how he used the opportunity to urge the Russians to join an international program to test nuclear weapons against Earth-approaching asteroids. In telling the history of these events, we also further describe the technology that could be used for such space defense systems.

This time NASA responded quickly to the Congressional initiative, and within two weeks they appointed Gene Shoemaker to chair a new NEO detection study. We were both among the alumnae of the Spaceguard Working Group who provided continuity with previous work. The weapons labs were represented by Teller protege Greg Canavan, a senior physicist at Los Alamos National Laboratory and a former Air Force officer. The Air Force also responded positively, and they were represented on the Shoemaker committee by both Col. Pete Worden, recently appointed Commander of Falcon Air Force Base, and civilian John Darrah, Chief Scientist of the USAF Space Command.