Now the huge crescent of the moon spanned the sky, the jagged mountain peaks along the terminator burning with the fierce light of the lunar dawn. But the dusty plains still untouched by the sun were not completely dark; they were glowing faintly in the light reflected from Earth’s clouds and continents. And scattered here and there across that once-dead landscape were the glowing fireflies that marked the first permanent settlements mankind had built beyond the home planet; Captain Singh could easily locate Clavius Base, Port Armstrong, Plato City…. He could even see the necklace of faint lights along the Translunar Railroad, bringing its precious cargo of water from the ice mines at the South Pole. And there was the Sinus Iridum, where he had achieved his first brief moment of fame a lifetime ago.
Earth was only two hours away.
Encounter Four
Kali 2 entered the atmosphere just before sunrise, a hundred kilometers above Hawaii. Instantly, the gigantic fireball brought a false dawn to the Pacific, awakening the wildlife on its myriad islands. But few humans; not many were asleep this night of nights, except those who had sought the oblivion of drugs.
Over New Zealand the heat of the orbiting furnace ignited forests and melted the snow on mountaintops, triggering avalanches into the valleys beneath. By great good fortune, the main thermal impact was on the Antarctic—the one continent that could best absorb it. Even Kali could not strip away all the kilometers of polar ice, but the Great Thaw would change coastlines all around the world.
No one who survived hearing it could ever describe the sound of Kali’s passage; none of the recordings were more than feeble echoes. The video coverage, of course, was superb, and would be watched in awe for generations to come. But nothing could ever compare with the fearsome reality.
Two minutes after it had sliced into the atmosphere, Kali reentered space. Its closest approach to Earth had been sixty kilometers. In that two minutes it took a hundred thousand lives and did a trillion dollars’ worth of damage.
The human race had been very, very lucky.
Next time it would be much better prepared. Though the encounter had altered Kali’s orbit so drastically that it would never again be a danger to Earth, there were a billion other flying mountains orbiting the sun.
And Comet Swift-Tuttle was already accelerating toward perihelion. There was still plenty of time for it to change its mind again.
Sources and Acknowledgments
MY INVOLVEMENT WITH THE SUBJECT OF ASTEROID IMPACTS IS now beginning to resemble a DNA molecule: the strands of fact and fiction are becoming inextricably entwined. Let me try to unravel them by taking the chronological approach.
Back in 1973 Rendezvous with Rama opened with the words:
Sooner or later, it was bound to happen. On June 30, 1908, Moscow escaped destruction by three hours and four thousand kilometers—a margin invisibly small by the standards of the universe. On February 12, 1947, another Russian city had a still narrower escape, when the second great meteorite of the twentieth century detonated less than four hundred kilometers from Vladivostok, with an explosion rivaling that of the newly invented uranium bomb.
In those days there was nothing that men could do to protect themselves against the last random shots in the cosmic bombardment that had once scarred the face of the Moon. The meteorites of 1908 and 1947 had struck uninhabited wilderness; but by the end of the twenty-first century there was no region left on Earth that could be safely used for celestial target practice. The human race had spread from pole to pole. And so, inevitably…
At 0946 GMT on the morning of September 11 in the exceptionally beautiful summer of the year 2077, most of the inhabitants of Europe saw a dazzling fireball appear in the eastern sky. Within seconds it was brighter than the sun, and as it moved across the heavens—at first in utter silence—it left behind it a churning column of dust and smoke.
Moving at fifty kilometers a second, a thousand tons of rock and metal impacted on the plains of northern Italy, destroying in a few flaming moments the labor of centuries. The cities of Padua and Verona were wiped from the face of the Earth; and the last glories of Venice sank forever beneath the seas as the waters of the Adriatic came thundering landward after the hammer blow from space.
Six hundred thousand people died, and the total damage was more than a trillion dollars. But the loss to art, to history, to science—to the whole human race, for the rest of time—was beyond all computation. It was as if a great war had been fought and lost in a single morning, and few could draw much pleasure from the fact that, as the dust of destruction slowly settled, for months the whole world witnessed the most splendid dawns and sunsets since Krakatoa.
After the initial shock, mankind reacted with a determination and a unity that no earlier age could have shown. Such a disaster, it was realized, might not occur again for a thousand years—but it might occur tomorrow. And the next time the consequences could be even worse.
Very well; there would be no next time.
So began Project Spaceguard.
Contrary to general belief, when I ended the novel with the words “The Ramans did everything in threes,” I had not the slightest intention of writing a sequel, still less a trilogy. It seemed a neat ending, and was in fact an afterthought. It took the intervention of Peter Guber and Gentry Lee to make me change my mind (see the introduction to Rama II) and no one was more surprised than I to find myself revisiting Rama in 1986.
But by then something else had happened, making asteroid impacts front-page news. In a famous paper (“Extraterrestrial Cause for the Cretaceous-Tertiary Extinction”: Science, 1980) Nobel Laureate Luis Alvarez and his geologist son, Dr. Walter Alvarez, had advanced a startling theory to explain the mysteriously sudden demise of the dinosaurs—perhaps the most successful life-form ever to arise on Planet Earth, next to sharks and cockroaches. As everyone now knows, the Alvarezes showed that a worldwide catastrophic event had occurred about sixty-five million years ago, and they produced evidence strongly suggesting that an asteroid was responsible. The direct impact, and the subsequent environmental damage, would have had a devastating effect on all terrestrial life—especially the larger land animals.
By a curious coincidence Luis Alvarez also had a major but fortunately beneficial impact upon my life. In 1941, as head of a team at MIT’s Radiation Lab, he invented and developed the radar blind-landing system later known as GCA (ground controlled approach). The Royal Air Force—then losing more aircraft to the British weather than to the Luftwaffe—was extremely impressed by the demonstrations, and the first experimental unit was shipped to England in 1943. As an RAF radar officer, I had the fascinating, and often frustrating, job of keeping the Mark I operational until the first factory models rolled off the production line. My only non-sf novel, Glide Path (1963), is based on that experience, and is dedicated to “Luie” and his colleagues.
Luie left GCA shortly before I arrived, and flew over Hiroshima on that fateful August day in 1945 to observe the operation of the bomb he had helped design. I did not catch up with him until several years later, at the University of California’s Berkeley campus; the last time we met was at the twenty-fifth GCA reunion in Boston, 1971. I am sorry that I never had a chance to discuss his dinosaur-extinction theory with him; in one of the last letters I received from him, he said it was no longer a theory but a fact.
Little more than a year before his death on September 1, 1988, Luie asked me to write a “puff” to be printed on the jacket of his forthcoming autobiography: Alvarez: Adventures of a Physicist (Basic Books, 1987). I was more than happy to do so, and would like to repeat what is now, alas, a posthumous tribute:
Luis seems to have been there at most of the high points of modern physics—and responsible for many of them. His entertaining book covers so much ground that even nonscientists can enjoy it: who else has invented vital radar systems, hunted for magnetic monopoles at the South Pole, shot down UFOs and Kennedy assassination nuts, watched the first two atomic explosions from the air—and prov
ed that (surprisingly) there are no hidden chambers or passageways inside Chephren’s pyramid?
And now he’s engaged on his most spectacular piece of scientific detection, as he unravels the biggest whodunit of all time—the extinction of the dinosaurs. He and his son Walter are sure they’ve found the murder weapon in the Crime of the Eons….
Since Luie’s death, the evidence for at least one major meteor (or small asteroid) impact has accumulated, and several possible sites have been identified—the current favorite being a buried crater, 180 kilometers across, at Chicxulub, on the Yucatan Peninsula.
Some geologists are still fighting stubbornly for a purely terrestrial explanation of dinosaur extinction (e.g., volcanoes), and it may well turn out that there is truth in both hypotheses. But the Meteor Mafia appears to be winning, if only because its scenario is much the most dramatic.
In any case, no one doubts that major impacts have occurred in the past—after all, there have been two hits and one near miss in this century (Tunguska, 1908: Sikhote-Alin, 1947: Oregon, 1972). The question to be decided is: how serious is the danger, and what—if anything—can be done about it?
During the 1980s there was widespread discussion of the problem in the scientific community, and the close passage of asteroid 1989FC (which missed Earth by a mere 650,000 kilometers) brought the matter to a head. As a result, the U.S. House of Representatives Committee on Science, Space, and Technology included the following paragraph in the NASA Authorization Act of 1990:
The Committee therefore directs that NASA undertake two workshop studies. The first would define a program for dramatically increasing the detection rate of Earth-orbit-crossing asteroids; this study would address the costs, schedule, technology, and equipment required for precise definition of the orbits of such bodies. The second study would define systems and technologies to alter the orbits of such asteroids or to destroy them if they should pose a danger to life on Earth. The Committee recommends international participation in these studies and suggests that they be conducted within a year of the passage of this legislation.
This may prove to be a historic document: who would have believed, only a few years ago, that a congressional committee would have issued such a statement?
As directed, NASA set up the International Near-Earth-Object Detection Workshop, which held several meetings in 1991. The results were summarized in a report prepared by the Jet Propulsion Laboratory, Pasadena: “The Spaceguard Survey” (January 25, 1992). The opening paragraph of its final chapter reads:
Concern over the cosmic impact hazard motivated the U.S. Congress to request that NASA conduct a workshop to study ways to achieve a substantial acceleration in the discovery rate for near-Earth asteroids. This report outlines an international survey network of ground-based telescopes that could increase the monthly discovery rate of such asteroids from a few to as many as a thousand. Such a program would reduce the time scale required for a nearly complete census of large Earth-crossing asteroids from several centuries (at the current discovery rate) to about 25 years. We call this proposed survey program the Spaceguard Survey, borrowing the name from the similar project suggested by science-fiction author Arthur C. Clarke nearly 20 years ago in his novel Rendezvous with Rama.
The Hammer of God could not possibly have been written without the masses of information contained in “The Spaceguard Survey”—but the direct inspiration for the novel came from a quite different, and very unexpected, source.
In May 1992 I was flattered to receive a letter from Steve Koepp, senior editor of Time magazine, asking me to write a 4000-word story that would “give readers a snapshot of life on Earth in the next millennium.” He added engagingly: “I believe it would be the first time that our magazine has ever published fiction (intentionally, at least).”
As it turned out, this information was not quite accurate. Time’s editors later informed me, rather apologetically, that mine was not the first fiction they had ever commissioned. Back in 1969 they had published a story by Aleksandr Solzhenitsyn. I am honored to follow in such distinguished footsteps.
Time’s suggestion was, needless to say, an offer I couldn’t refuse. It presented an interesting challenge, and I do not recall a delay of more than five milliseconds before I realized that the perfect subject was already at hand. More than that—it was my duty to show what could be done about the asteroid menace. By creating a self-fulfilling prophecy I might even save the world—though I’d never know….
So I wrote The Hammer of God and rushed it off to Time, where Steve Koepp justified his existence by making some very shrewd editorial suggestions, 90 percent of which I accepted with (fairly) good grace. It appeared in the special issue of the magazine, Beyond the Year 2000, published in late September and dated Fall 1992 (Vol. 140, No. 27).
Before then, however, I had gone to England for the slightly premature celebrations of my seventy-fifth birthday (after three decades of living less than a thousand kilometers from the Equator, nothing will get me to the U.K. in December). Among the participants in the program that my brother Fred had arranged in my hometown, Minehead, was one of the members of the Spaceguard Survey, Dr. Duncan Steel. He had come all the way around the world, from the Anglo-Australian Observatory, Coonabarabran, NSW, to present a paper showing, with some awesome color slides, what might happen in the event of a major impact.
It was probably around this time that I accepted the fact that Hammer was really a compressed novel—and that I had no alternative but to decompress it. As I had six other books and several dozen TV programs in orbit, I was reluctant to bite this particular bullet, but eventually decided to cooperate with the inevitable.
The first draft was almost complete when I received a letter from Dr. Steel, now back in Coonabarabran, with some startling news:
Until last Thursday, if anyone had asked me when an asteroid or comet was going to collide with the Earth, I could have put my hand on my heart and told them that none of the currently-known objects is going to hit our planet in the foreseeable future (meaning a century or two). This is no longer the case….
Attached to Dr. Steel’s letter was Circular 5636, dated October 15, 1992, from the Central Bureau for Astronomical Telegrams, which is part of the Smithsonian Astrophysical Observatory, Cambridge, Massachusetts. It reported the rediscovery on September 26 of Comet Swift-Tuttle, originally discovered by two American astronomers in 1862—and then lost, not through carelessness but for a much more interesting reason.
When it nears the sun, Swift-Tuttle, like many comets (including Halley) undergoes solar-powered jet propulsion, the operation of which is completely unpredictable. Though the effect on its orbit is quite small, as Dr. Steel remarks: “If the sums and models are slightly incorrect—and one might not expect this jetting force to act consistently—then the comet may hit the Earth on August 14, 2126. There is no doubt about the date, since that is the date on which the comet’s orbit intersects that of the Earth in that year; what is uncertain at this stage is whether the comet will be there at that time as well, or whether (hopefully) it will be slightly further on or back in its orbit.”
Understandably, the Astronomical Union Circular suggests: “It therefore seems prudent to attempt to follow Swift-Tuttle for as long as possible after the present perihelion passage, in the hope that an adequate orbit determination… can be made.”
Duncan Steel again: “What if the comet does hit the Earth in 2126? This will occur at a speed of 60 km/sec. The nucleus is about 5 km in size, so the kilotonnage released, according to my calculations, would be equivalent to 200 million megatons, or 10 billion times the Hiroshima bomb. If 5 km were its diameter rather than radius, divide those figures by eight. Still a big bang in anybody’s language. Best wishes—Duncan.”
Now, I had set the arrival of my hypothetical Kali around 2110—at which date the real world may be starting to agonize over Swift-Tuttle, only sixteen years ahead. So I was very happy to use this information to “add an air of verisimilitude to
an otherwise bald and unconvincing narrative,” as The Mikado puts it so neatly.
Now, here is something that no one is going to believe….
I was still polishing this chapter when I switched on CNN (the exact time: 6:20 P.M., November 6, 1992, just two hours ago). Imagine my amazement at seeing my old friend the Dutch-American astronomer Tom Gehrels, expert on asteroids and a prominent member of the Spaceguard team. He has visited Sri Lanka on several occasions, hoping to establish an observatory there: his engaging autobiography, On the Glassy Sea (American Institute of Physics, 1988), has a chapter headed “Sri Lanka’s Telescope and Arthur C. Clarke.”
And what is Tom doing on CNN? He’s just reporting the final confirmation of the Alvarez theory. The smoking gun has been found—and ground zero is, as I mentioned a few pages earlier, the Chicxulub structure in Yucatan.
Thank you, Tom: how I wish Luie were still around to hear the news.
Another odd coincidence took place soon after Hammer was published: a small meteorite landed in New York, of all places—damaging a parked car! (What else could it hit?) At least, that was the story I heard, but I am understandably skeptical. I cannot help wondering if Time’s publicity department was somehow involved….
This incident, however, reminds me of the movie Meteor, which I enjoyed more than most of the critics. I have a very high threshold of tolerance for bad sf films. After persuading him to view one classic (Things to Come, I believe), Stanley Kubrick complained: “What are you trying to do to me? I’ll never see another movie you recommend!”
There is a brilliant throwaway line at the climax of Meteor. After the bombardment from space, the Russian scientist and his American counterpart have just struggled back to the surface, having taken shelter in the New York subway. They are both covered with mud from head to foot. The Russian turns to his colleague and says: “Someday I must show you the Moscow Underground.”