May 22-26, 1995
The Livermore meeting on planetary defense was attended by approximately 150 persons, primarily scientists associated with the DOE weapons labs (Livermore, Los Alamos, and Sandia), the military services, and their contractors, but also including a substantial number of academic scientists. While the attendance was primarily by Americans, there were also a dozen attendees from Russia and smaller delegations from Japan, China, Italy, and the Czech Republic. This workshop was considered a successor to the Near Earth Object Interception Workshop held at Los Alamos, New Mexico, in January 1992, and the Space Protection of the Earth conference held at Snezinsk, Russia, in September 1994. The conference was organized into two days of invited talks presented in plenary sessions, followed by individual working panels dealing with the Impact Threat (Gene Shoemaker, Chair), Detection (John Darrah, Chair), Experiments (John Mansfield and Stewart Nozette, Chairs), Interdiction (Vadim Simonenko, Chair), and Integration (Greg Canavan, Chair). Each of the Panel Chairs presented the results of their workshops at the end of the meeting. The Chair of the Organizing Committee was John Nuckolls, former Director of Livermore Laboratory.
A wide variety of technical issues were discussed at the meeting, including the nature of the impact hazard (O. Toon. D. Morrison, I. Nemtchinov, P. Ward, J. Hills), the impact flux (G. Shoemaker), the nature of NEOs (J. Lewis), detection of NEOs (A. Harris, T. Gehrels, E. Bowell, J. Darrah, T. Karr, J. Rather), interception and interdiction (S. Nozette, V. Simonenko, J. Solem, L. Wood), and cost-benefit analysis of impact defense (G. Canavan). Edward Teller presented the banquet talk on the subject of "The need for experiments on comets and asteroids". Although most of the material had been discussed at previous meetings, three general themes emerged, which set this meeting somewhat apart from previous conferences on the NEO hazard.
The most notable difference was a focus on NEOs in the hundreds of meter diameter range, an emphasis that was highlighted by Nuckolls in his opening remarks and repeated by many speakers. While it was conceded that the greatest total hazard was associated with objects large enough to precipitate global catastrophe (>10^6 MT), many of the attendees felt it was equally important to deal with the smaller, more frequent impactors that might produce highly destructive tsunamis. The work of Jack Hills on the effects of tsunamis was widely cited in defense of this position. In his banquet talk, Teller particularly discussed 100 MT (100 m diameter) impacts, which have a few percent likelihood of happening in the 21st century and which could cause tsunamis large enough to devastate a continental coastline (e.g., the east coast of the U.S. from Long Island to Florida). He argued that a few percent threat of such an event, which could "cause millions of dollars in damage and kill thousands -- perhaps many thousands -- of people" was sufficient to justify a mitigation program at the level of "perhaps $100 million per year".
A second focus was on development of non-nuclear mitigation strategies. Lowell Wood led here in proposing kinetic energy weapons that could "slice up" asteroids with diameters of tens of meters, and he repeatedly argued for experimental tests of such systems. In his summation on Integration, Greg Canavan took note of the fact that he had described a systems response to the NEO threat without ever using the term "nuclear"; his point was that all of the basic elements of the system (detection, tracking, launch systems, interception, command-and-control) were identical for nuclear and conventional responses, and there was no need to raise issues of nuclear explosives in order to support a vigorous program of NEO mitigation.
The third theme was the opportunity presented by the decommissioning of some 300 Russian SS-18 ICBMs, which could be modified to launch payloads for NEO reconnaissance and later active experiments. Stu Nozette and others argued for the importance of microsatellites that could be launched to intercept NEOs with the SS-18. It was emphasized by several speakers that the availability of this unique launch-vehicle resource was limited to the period from now till 2002, the date by which these launchers should be destroyed according the the timetable of the START-2 treaty. In general, it was felt that efforts should be made to utilize the strong but perhaps transient Russian capability to advance the timetable for interdiction experiments.
Both a summary report and a transactions publication are anticipated from the Livermore defense conference, but details for both remain to be defined.