Early on the morning of 1 February 1994, President Clinton, Vice-President Gore, the Joint Chiefs of Staff and the members of the National Security Council were awakened from their sleep by Pentagon officials.footnote＊ A military surveillance satellite had detected the brilliant flash of a nuclear explosion over the western Pacific. There was intense concern that the strategic warheads aboard a Russian or Chinese missile submarine accidentally might have detonated. Military aircraft, however, failed to detect any unusual radiation in the indicated ocean sector, and defence intelligence experts soon concluded that the satellite had actually witnessed the explosion of an asteroid fragment, later estimated to have been the equivalent of a 200-kiloton nuclear blast. The President went back to bed.footnote1
Five months later, beginning on 16 July, hundreds of millions watched in awe as the Hubble space telescope transmitted images of Comet Shoemaker-Levy 9’s fiery death in the dense atmosphere of Jupiter. For nearly a week, the
These events made 1994 something of a watershed in public awareness of the Earth’s vulnerability to comet and asteroid bombardment.footnote3 Indeed, the spectators at Shoemaker-Levy 9’s immolation were the first generation of humans to observe a major planetary impact since medieval monks recorded the collision of an asteroid with the moon, forming the crater Giordano Bruno, in 1178.footnote4 Congress was sufficiently impressed to fast-track a major study of neo-detection technology and a probe to the asteroid Eros—launched on 16 February.footnote5 Meanwhile, the friends of Star Wars, including H-bomb father Edward Teller, lobbied for an orbital anti-asteroid defence of super-lasers and thermonuclear weapons. (Both of which, as Carl Sagan and others immediately pointed out, could be turned against Saddam Husseins on Earth as easily as neos.)footnote6
Beyond the predictable media hyperbole about exterminators from outer space—so reminiscent of ‘comet hysteria’ throughout human history—the events of 1994 were also an incomparable ‘teach-in’ on the Earth’s citizenship in the solar system. February’s giant fireball over the Pacific, July’s fusillade against Jupiter, and December’s breathtaking near-miss—were all cram sessions in the new Earth science being shaped by comparative planetology and the neo-catastrophist reinterpretation of the stratigraphic record. It is a lesson, of course, that many geologists, as well as geographers and historians, have great difficulty accepting. Even
But this is not a mere family feud. The ‘golden age’ of Cold War space exploration, now drawn to a close, has seeded the fields of philosophy with discoveries every bit as strange and revelatory as those of Magellan and Galileo—the names, appropriately enough, of our most recent planetary galleons. I must confess that as an ageing socialist, who spent the glory years of the Apollo program protesting the genocidal bombing of Indochina, it has taken me half a lifetime to warm to a scientific culture incubated within Cold War militarism and technological triumphalism. Yet it is also the contemporary home of luminous and, dare I say, revolutionary attempts to rethink the Earth and evolution within the new context of other planetary histories.
While postmodernism has defoliated the humanities and turned textualism into a prison-house of the soul, the natural sciences—which now include planetology, exobiology and biogeochemistryfootnote7—have once again, as in the time of Darwin, Wallace, Huxley and Marx, become the sites of extraordinary debates that resonate at the deepest levels of human culture. In this article, I explore how one debate—over the role of asteroid and comet impacts in mass-extinction events—has opened a door to a new vision of the Earth, and, even perhaps, of human history.
I begin with a polemical question: if postwar oceanography produced a revolution known as ‘plate tectonics’, what has the geological exploration of the solar system produced? This is a ploy to discuss the ‘axiomatic’ deep structure of traditional Earth science, surprisingly undisturbed by plate tectonics but mortally threatened by the post-Newtonian perspective of comparative planetology. A review of the debate over impact tectonics and ‘coherent catastrophism’ then introduces three case-studies: Herbert Shaw’s Craters, Cosmos, and Chronicles (1994) is a disconcerting work—of Rabelaisian energy and squalor—which uses non-linear dynamical systems theory (a.k.a. chaos theory) to rethink Earth history as the ‘coevolution’ of mantle dynamics and asteroid bombardment.footnote8 Stuart Ross Taylor’s Solar System Evolution: A New