Cosmic collisions can provide fun and entertainment for the whole family. “Simulate the damage caused by comet and asteroid collisions with Impact: Earth!” one game maker advertises on the Internet, mentioning Chelyabinsk. “Impact: Earth! is an interactive tool that lets anyone calculate the damage a comet or asteroid would cause if it happened to collide with our planet. You can customize the size and speed of the incoming object, and then find out if mankind survives. (Usually it does.)”34 WHEW!
The situation is perhaps best explained on a “human” level by Maksim Y. Nikulin, who owns a circus in Moscow where children can have their pictures taken sitting next to a full-grown Siberian tigress named Chanel. He claimed that the sessions are safe. Besides, he said, the appearance of danger is interesting and integral to the circus arts. “People go to the circus for adrenaline…. If it appeared to be entirely safe it would not be interesting.”35
What happened over Chelyabinsk may have startled the uninformed, but it came as no surprise to astronomers, other scientists, the international space community, and just about everyone who had learned about what happened to the dinosaurs and who took that seriously. The possibility that the worst-case “event”—Doomsday—could happen because of an asteroid or a comet impact, or even that a region could be devastated, had long since gotten governments’ attention and that of many ordinary people around the world who coalesced into groups dedicated to a new concept: planetary defense. Two generations that had thought a third world war, inevitably thermonuclear, would be the worst possible occurrence to be inflicted on humanity began to see and viscerally understand that nature could provide an even worse one, and not just to humanity, but to all of Earth and, therefore, to every living thing on it.
It is hard to overestimate how important the discovery at Chicxulub was. Everyone who had taken Astronomy 101 and learned about the potential world-ending violence in the universe, or who had visited a planetarium like the Hayden in New York and had gotten to see and touch a cold, hard, scarred meteor or a fragment of one, could sense what horrific destruction a large-enough impactor could cause. They could sense the carnage emotionally but could not imagine it clearly since it would be so massive that it was beyond clear conception. And catastrophic impacts, real and potential, were by no means only ancient history, relegated to Tyrannosaurus rex, Stegosaurus, Allosaurus, Pterodactylus, and the other creatures that disappeared when the light went out. The morning newspaper and the evening news carried stories of attacks on the planet, as they had for years. It was only a matter of noticing the evidence and establishing a pattern for the bombardment; of connecting the proverbial dots.
A “meteor shower” started over New York City on November 15, 1859, and lasted well into 1860 as fascinated New Yorkers watched the spectacular, panoramic sky show. On August 13, 1930, three meteors exploded over the upper Amazon with such force that hundreds of miles of jungle were set ablaze and continued to burn for months, covering the surviving trees in a vast area with a blanket of white ash and sending indigenous tribes fleeing in terror. On June 24, 1938, one estimated to have weighed 450 tons blew up roughly twelve miles above Chicora, Pennsylvania, and caused one apparent fatality: a cow. On August 3, 1963, a large bolide, which is loosely defined as a fireball, was detected 1,100 kilometers west-southwest of the Prince Edward Islands. On September 17, 1966, it was Lake Huron's turn when something exploded with a force equivalent to 0.6 kilotons of TNT over that body of water, which separates the state of Michigan and the province of Ontario, Canada. The Canadians got another one about five months later when a second meteor blew up thirteen kilometers above Alberta. The so-called Marshall Islands Fireball on February 1, 1994, was a double explosion that occurred with a force of eleven kilotons of TNT. That one was seen by an ambiguously named US military Defense Support Program 647 satellite, whose infrared eyes were designed to spot Soviet ballistic-missile tests and the hundreds of simultaneous hot spots that would have signaled an all-out missile attack and, therefore, the start of World War III.1 There was an airburst caused by three breakups 150 kilometers south of Greenland on December 12, 1997.
Walt Whitman was so taken by comets and that long meteor shower over New York that he rhapsodized about them in a poem he called “Year of Meteors (1859–60)” that was in Leaves of Grass:
Nor the comet that came unannounced out of the north, flaring in heaven;
Nor the strange huge meteor procession, dazzling and clear, shooting over our heads,
(a moment, a moment long, it sailed its balls of unearthly light over our heads,
Then departed, dropt in the night, and was gone;)2
Giotto's fresco The Star of Bethlehem shows a comet that some say is Halley's and that Giotto apparently interpreted as having spiritually religious significance. Van Gogh's Starry Night is a depiction of rather violent heavenly motion that is very likely cometary, and Charles Piazzi Smyth, who was an astronomer, portrayed the Great Comet of 1843 in a painting of that name that had a long, elegant tail that stretched diagonally across the entire canvas. There is also a dramatic engraving of the same comet passing over Paris. But it was interpreted, as the appearance of comets often are, as having a sinister side, as well; of heralding impending disaster. That notion was spread by William Miller, a Bible-thumping, former Long Island farmer in Hampton, New York, who was a captain in the army during the War of 1812 and who fell off the back of a wagon and landed on his head. Then he began having delusions that Earth would be destroyed by fire in 1843, when Christ would appear and raise the believers before the planet was purified by fire. Miller was convinced that when the comet appeared, it would signal the beginning of the transformation. Prophet Miller had some fifty thousand true believers.3 Arthur C. Clarke may very well have had the Millerites (as they were called) in mind when he described The Reborn's trying to sabotage the mission to head off Kali in The Hammer of God.
There were many others in the late nineteenth and early twentieth centuries, however, who did not find asteroids and comets romantic or the heralds of paradise everlasting. Religious or secular, they looked at the record of destruction and decided to organize to learn as much as possible about the phenomenon and, in so doing, perhaps prevent more devastation, at least on a large scale. And the religious among them believed, and continue to believe, that the supreme being who created this world wants it and its inhabitants to survive and thrive, not demolished in a colossal explosion or disappear in an all-consuming fire. They decided that the only rational way to address the danger was to understand it, confront it, and create a protective system that included private organizations, governments, and, eventually, an international alliance to protect the planet.
What happened over Tunguska was well known within the world science community and so was what occurred over Brazil in 1930 and elsewhere, including Chicora, British Columbia in March 1965, Lake Huron that same year, and Chelyabinsk, which took its first hit in April 1944. Those “events” ratified the discovery at Chicxulub, and common knowledge about what happened to the dinosaurs did indeed make the situation seem like Russian roulette, with five chambers in the revolver being empty and the sixth containing a bullet that could end it all forever. The risk that near-Earth objects (NEOs) pose is usually perceived as a function of both the culture and the science of human society. “NEOs have been understood differently throughout history,” Luis Fernández Carril, a Mexican climatologist, has written. Every time an NEO is seen, “a different risk was posed, and throughout time that risk perception has evolved. It is not just a matter of scientific knowledge.” The perception of risk is therefore “a product of religious belief, philosophic principles, scientific understanding, technological capabilities, and even economical resourcefulness.”4
People did indeed bring their own beliefs, principles, and scientific understanding to the subject. But the common denominator was the amalgamation of knowledge about what did in the dinosaurs, what happened at Tunguska, the discovery at Yucatan and of other craters all over th
e place, and the sightings of flaming objects all over the world. That caused deep concern among many organizations, including the national space programs, and among informed individuals, many of whom coalesced into organizations that were specifically dedicated to addressing the impact threat and all its ramifications. It galvanized thousands of individuals who, out of concern for the long-term safety of their planet, expanded their worldview beyond politics, economics, and traditional international relations. Preventing the end of the world and, in turn, the end of human existence—no great-grandchildren; no descendants at all; oblivion—became the ultimate, most consequential cause. In Samuel Johnson's immortal words, “Depend upon it, sir, when a man knows he is going to be hanged in a fortnight, it concentrates his mind wonderfully.”
It certainly concentrated the National Aeronautics and Space Administration's collective mind. The threat comes from space, and as the nation's space agency, NASA had to meet that threat by taking on planetary defense. The glory days of the Apollo program were two decades old, its imaginative Skylab program was a fading memory, and Solar System exploration was drying up in the wake of the sensational Pioneer and Voyager missions of the 1970s. Its participation in constructing the International Space Station (ISS) starting in 1998 was a shared, distant, and somewhat embarrassing goal. What haunted NASA (but was never talked about in public) was the fact that the ISS was built as a long-duration training vehicle so that astronauts, cosmonauts, and spacemen and spacewomen from other nations could form an international partnership and practice for the eventual trip to Mars, which is a year each way, and have physicians, psychologists, and others see how they reacted physically, mentally, and emotionally to so long a stint in space. The Mars mission was always elusively theoretical—a brew of fact and fiction that was equal parts Wernher von Braun and Robert A. Heinlein. It was part of a grand program called Constellation in which astronauts were to return to the Moon and others were to head for Mars, which a succession of robotic spacecraft, the latest being Curiosity, have carefully scouted. But with pressing needs on Earth and a budget deficit of $1.29 trillion (the second highest ever), President Barak Obama cancelled Constellation—aborted it, as they say in spaceworld—in 2010. Given the nation's pressing needs, including paying off wars in Iraq and Afghanistan and maintaining the armed forces (while warily watching China expand its sphere of military influence), sending people back to the Moon and then to Mars was seen as being frivolous. (For their part, China's leaders once proclaimed that they intended to send taikonauts to the Moon in an evident effort to demonstrate that their country was a superpower that was up to that task, but then they quietly abandoned the plan, no doubt because they decided that the price of the ticket was not worth the trip.)
There was nothing frivolous about the asteroid and comet threat, though. So that pivotal year—1998—NASA established the Near-Earth Object Program Office at the Jet Propulsion Laboratory (JPL) to coordinate the detection, tracking, and characterization (that is, the size, shape, weight, and composition) of the potentially hazardous asteroids and comets that prowled the neighborhood. Behemoths that can cause extinctions are rare and tend to turn up roughly once a century, whereas most NEOs are relatively small. But so is a bomb that can demolish a house.
“These are objects that are difficult to detect because of their relatively small size but are large enough to cause global effects if one hit the Earth,” explained Don Yeomans, the JPL astrophysicist who became the Near-Earth Object Program Office's first director and who would write an informative and digestible primer on the situation, Near-Earth Objects: Finding Them before They Find Us, that ought to be required reading at every university on the planet. The book's importance extends beyond explaining the potential danger to lay people because, in addition to its technical responsibilities, the NEO Program Office is supposed to facilitate communication between the astronomers and other scientists who would have to deal with a potentially calamitous approaching asteroid or comet and a public that would range from being utterly ignorant and oblivious to being hysterical. Yeomans bridged that chasm with Near-Earth Objects, which amounts to a briefing manual that is very important for making clear what a collision or another very near miss would mean to Earth. The other mission NASA was ordered to take on in that fateful year of 1998, of course, was compiling the Spaceguard Survey—the catalog—within a decade, which it did.
A planetary “hanging” (to use that metaphor) concentrated Maj. Lindley N. Johnson's mind, too. Johnson was a US Air Force officer who invented the term planetary defense in a white paper he wrote in 1993 for the Air University SpaceCast 2020 study to determine what capabilities the air force should have in the post–Cold War world. The paper, Preparing for Planetary Defense: Detection and Interception of Asteroids on Collision Course with Earth, began with the assumption that a defensive system was definitely required and then made the point that the necessary technologies, including nuclear explosives, missile propulsion systems, guidance, and targeting, were effectively Cold War surplus and were therefore available. And since the threat is global, he added, the expense of operating the system should be shared by many nations. “The cost for such a system, which might be analogous to buying life insurance, also rightly belongs in the international arena,” he wrote. The clear implication was that, given the consequences of a lack of defense against impactors, the expense would be inconsequential.5 “What's your life worth?” was the unstated but clearly implied question.
Preparing for Planetary Defense described the problem at length, providing necessary background details on the objects, their destructive potential, and mentioning the usual suspects: the Tunguska and Chicxulub impactors and Shoemaker-Levy 9's attack on Jupiter. “Now that it is recognized that collisions with objects larger than a few hundred meters not only can threaten humanity on a global scale but have a finite probability of occurring, means for mitigating them seem clearly worth investigation,” Johnson stated emphatically up front. “It should also be recognized that the technology required for a system to mitigate the most likely of impact scenarios is, with a little concerted effort, within humanity's grasp.”6 The technology consists of rockets carrying robots for distant intercepts that would deflect the approaching rock or comet—the old nudge-it-off-course-very-far-from-Earth technique—and a second requiring a forceful deflection with the use of “high energy options” that included nuclear and kinetic weapons that were then available and, within two decades, lasers and ultrahigh kinetic energy systems. And the paper looked to the distant future and mentioned antimatter weapons, mass drivers, solar sails that would use the Sun's radiant energy to gently push the rock off course, and, in a truly impressive leap of imagination, “asteroid eaters” that would infest it with devices that would replicate themselves by feeding on the asteroid itself. They would, in other words, cannibalize it. “Over the period of several months or a few years, these devices, recreating themselves into an army of thousands, could completely mine the asteroid away, or at least reduce it to a size that is no longer a threat or is more easily maneuvered by the propulsion technology.” Pushing the asteroid off course, gently or with force, seems more practical and effective than staging a long-duration banquet. And Johnson makes no mention of excrement and what, if anything, to do with it. In any case, he did an enormous amount of homework, part of which included acquainting himself with The Hammer of God, which he was sure to mention.7
Two other air force officers, Lt. Col. Rosario Nici and 1st Lt. Douglas Kaupa, wrote “Planetary Defense: Department of Defense Cost for the Detection, Exploration, and Rendezvous Mission of Near-Earth Objects,” which appeared in Airpower Journal in 1997. They did their homework, too. After describing the NEO situation and the requisite impact sites, including Meteor Crater and Jupiter's perforated atmosphere—but also Manicouagan crater in Quebec and Wolfe Creek Crater in Australia—Nici and Kaupa maintained that the US government, through the Department of Defense, “is obligated to protect the lives and safety of its citizen
s,” and that the nation “may use its armed forces, under the hierarchy of interests, for cases of strict humanitarian concern. Thus, responding to the NEO threat could be seen to fall under this policy.”8 They noted that the chief of staff of the US Air Force had tasked Air Force Space Command to determine what would be needed for the defense of the planet by fiscal year 1997. Furthermore, an effective system had to include coordinated worldwide coverage of the sky, a determination of what sizes constitute progressively serious dangers, knowledge of the objects’ composition to help mitigation strategy, rendezvousing with an NEO to study it up close, practicing attacking and destroying one, “capturing” and mining an asteroid, and setting up a system that would warn about “small” ones that could save lives and prevent tsunamis, earthquakes, and forest fires.
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