Asteroid Threat : Defending Our Planet from Deadly Near-earth Objects (9781616149147)

by William E. Burrows

  As every police officer, sports coach, physician, lawyer, and businessman or businesswoman knows, competition requires knowing the opponent, and the more thoroughly, the better. That certainly applies to planetary defense—to competition with NEOs—which is why the Spaceguard Survey called for increased observation, notably by optical astronomy, radar astronomy, and physical observation with photometric equipment. In common with other asteroid and comet watchers around the world, its collective membership also called for international cooperation. “That the hazard posed by NEO's is a problem for all humankind hardly needs repeating,” they repeated. “The likelihood of a particular spot being the target of an impact is independent of its geographic position, so that we are all equally at risk.”22

  The community has been well aware of the danger for decades. Congress got on board in 1998 after hearings were held that May. There, Clark Chapman, William Ailor of the Aerospace Corporation, Gregory Canavan of the Los Alamos National Laboratory, John Lewis of the University of Arizona, and Carl Pilcher, the director of NASA's science program, testified about the threat and what was being done to address it.

  Pilcher told the Subcommittee on Space and Aeronautics that NASA was so concerned about what its and other telescopes picked up that it was committed to cataloging within a decade 90 percent of all NEOs with a diameter larger than one kilometer and that the program was on track to do so. He added that the budget for completing this task had been doubled to $3 million and that that allocation—relatively meager as it was—would at a minimum be maintained. Canavan told the subcommittee that improved technology had increased the detection rate, but that long-period comets—those that cross Earth's path—remained a serious concern and could constitute as much as half of the NEO threat. He also repeated the axiom that asteroids had to be characterized (meaning adequately defined) for their threat to be reduced, and he called for cooperation between the Department of Defense and NASA, as happened in the Clementine II mission in 1994, when they combined to test spacecraft components and sensors by sending the spacecraft to observe the Moon and asteroid 1620 Geographos. Usable data came back from the Moon but not from the asteroid because of a technical malfunction. Ailor discussed the Leonid meteor shower and the danger it would pose to satellites when it started in November. It was a spectacular show and caused no apparent harm to the Earth-circlers. And Lewis sounded a distinctly upbeat note by telling the subcommittee that asteroids were economically valuable because they could be mined, and he carefully pointed out that the keys to successful exploitation for minerals were lower launch costs and carefully choosing asteroids that are the most accessible and have the richest mineral concentrations.23

  The congressmen, clearly impressed by the presentations, reacted by reaffirming what NASA was already doing. They formally mandated it to catalog within a decade—by 2008—90 percent of near-Earth asteroids (NEAs) a kilometer or larger, and that became the Spaceguard Survey. The name memorializes Arthur C. Clarke: Saint Arthur, the Visionary. Many others have decided to pay homage to Clarke the same way. The International Astronomical Union's Working Group on Near-Earth Objects held a workshop in 1995, beginning the Space Survey, which led to the creation of the private, international Spaceguard Foundation that was started in Italy in 1996 and that is dedicated to discovering and studying NEOs. There is also a Japan Spaceguard Association (which is based in Tokyo) and the Bisei Spaceguard Center (also in Japan), which do the same thing. And Spaceguard UK operates the Spaceguard Centre in Knighton, which was set up to provide information on asteroid and comet impacts, to find ways of predicting them, and to get that information to the news media and educational institutions.

  The relationship between Congress and NASA on identifying large NEOs became somewhat incestuous. The space agency announced that it planned to find and identify 90 percent of all NEOs that potentially threatened Earth. Then, as noted, Congress dutifully reacted by ordering NASA to find and identify 90 percent of all Earth-crossers that endangered the planet. The space agency reacted to the congressional order by proclaiming in September 2011 that, lo and behold, it had met the congressional goal and had found more than 90 percent of the rocks that could cause a planet-wide catastrophe.24

  Not to be left out, the US Air Force issued a report, Preparing for Planetary Defense: Detection and Interception of Asteroids on Collision Course with Earth, a thirty-three-page canon that recommended that the Department of Defense take an active role in planetary defense. It credited Congress with understanding the danger and ordering the creation of the International NEO Detection Workshop that produced the Spaceguard Survey and an NEO Interception Workshop that met in 1992 to come up with ways to intercept, deflect, or destroy anything that appears to be on a collision course with Earth. Putting the situation in perspective, the report opened by matter-of-factly asserting the following:

  Most humanity is oblivious to the prospect of cosmic collisions, but this hazard from space is a subject of deadly concern to the population of the planet. Work by several nationally recognized scientists who have been investigating this issue for a number of years, some for decades, has brought an awareness that, to the average citizen of the U.S., the risk of death may be just as great from an asteroid strike as from an aircraft accident. Those unfamiliar with these studies may find this incredulous when, in fact, there have been no recorded deaths due to asteroid strikes, albeit there have been close calls from small meteorites striking cars and houses. However, the probability is finite, and when it occurs, the resulting disaster is expected to be devastatingly catastrophic. But because we are dealing with events, time scales and forces well beyond the human experience, the threat is not universally recognized.25

  With the public's ignorance established, the report went on to describe the danger, citing the Alvarez group's work, the extinctions, and comet Shoemaker-Levy 9’s impending attack on Jupiter. Then it, too, called for an enhanced capability to find and characterize potential threats and come up with ways to prevent collisions. There are two ways to do that, the report stated: (1) propulsion, meaning a frontal attack to stop the asteroid by sending a rocket into it or by using nuclear energy and ultimately some hypervelocity, or antimatter weapons; and (2) deflection, which would involve nuclear and kinetic energy, lasers, and even putting solar sails on them that would gently move them off course.26

  The august Federation of American Scientists put out its own report, which had the same title as the Air Force report and which essentially said the same thing, as well as what was in the NASA Spaceguard Survey: the threat had to be clearly defined and then mitigated with an international response.

  The American Institute of Aeronautics and Astronautics (AIAA), which was started in 1963 as an amalgamation of the venerable and widely respected American Rocket Society and the American Interplanetary Society, has some thirty-five thousand individual members and ninety corporate members. It therefore wields considerable power in the aerospace world and weighed in with a position paper in October 2004 whose title, “Protecting Earth from Asteroids and Comets,” got right to the point. It led off by suggesting that an organization be created within the US government that would be specifically responsible for planetary defense and would be an interagency office charged with dealing with “all aspects of Planetary Defense.” It also proposed that a senior-level inter-agency working group be formed to define the appropriate makeup and reporting structure of the organization, develop a plan that would lead to its creation, and procure funding for its support. The AIAA paper also called for the office to establish a formal procedure for getting word out when the probability of an impact exceeds specified thresholds. And since the threat is global, it recommended starting a dialogue among other nations and international institutions to characterize the challenges that would be involved in an international deflection program. Furthermore, it called for broadening the Spaceguard Survey to include one-hundred-meter and larger NEOs; get more information about asteroids (including by missions to them so de
flection techniques could be developed); conduct actual flight tests to demonstrate the ability to change a potential impactor's orbit; and—getting to the human factor—sponsoring research to assess the political, social, legal, and disaster-relief consequences of a serious NEO threat, mitigation effort, or possible impact.

  “While noteworthy efforts are being made to detect threatening objects,” the paper concluded, “Earth is effectively blind to NEO objects of a size range that could lead to immediate and long term deaths of thousands to millions of people and is unprepared should a short term threat be detected.”27

  By suggesting that a national organization be created that would be responsible for overseeing the asteroid and comet threat, the institute was clearly implying that NASA had too many other projects and programs to be able to adequately concentrate on this most important mission. That was not the case, though. If anything, the space agency needed a major program that would fill the void left by the ending of Apollo in 1972. It therefore decided that planetary defense should be handled by the space agency. Congress agreed. By 2005, the legislators were so concerned about the asteroid and comet population that the NASA authorization act substantially lowered the minimum size that had to be located and studied to 140 meters. Its charge to NASA clearly reflected its concern:

  The Congress declares that the general welfare and security of the United States require that the unique competence of the National Aeronautics and Space Administration be directed to detecting, tracking, cataloguing, and characterizing Near-Earth Asteroids and comets in order to provide warning and mitigation of the potential hazard of such Near-Earth Objects to the Earth.

  The Administrator shall plan, develop and implement a Near-Earth Object Survey program to detect, track, catalogue and characterize the physical characteristics of Near-Earth Objects equal to or greater than 140 meters in diameter in order to assess the threat of such Near-Earth Objects to the Earth. It shall be the goal of the Survey program to achieve 90 percent completion of its Near-Earth Object catalogue (based on statistically predicted populations of Near-Earth Objects) within 15 years after the date of enactment of this Act.28

  That officially started the Spaceguard Survey, which stands as a milestone in the new quest for planetary defense.

  The National Research Council (NRC), which is the investigative division of the National Academy of Sciences, the nation's preeminent and ultra-prestigious science body, also took an interest in the menacing meteors and their icy cohorts. Its fourteen-member Survey and Detection Panel held three-day fact-finding hearings in Washington, Tucson, and Santa Fe in 2009, at which scientists, other specialists, and a NASA representative made presentations that described the NEO situation in copious detail. As was customary, the presentations described what comets, asteroids, and their low-flying derivatives, meteors, are; what threat they pose; and how that threat can be (yes…) mitigated. Tucson may have been picked so attendees could supplement the scholarly presentations with a day trip to nearby Meteor Crater to see firsthand what the impactors their colleagues were describing could do.

  Maj. Lindley N. Johnson, the NEO Observations Program executive of NASA's Planetary Science Division, presented an overview of the NEO situation. His presentation included an outline of the NEOs’ history and what effects they would have, based on their size and average impact interval, starting with a puny meteor under fifty meters that would break up high in the atmosphere and cause no damage and progressing to ever-larger ones. Larger space objects that are bigger than fifty meters would cause a Tunguska-like event; bigger than 140 meters would cause a regional event; a kilometer or bigger would have a relatively serious global effect; and one that is ten kilometers or bigger, which occurs only once every one hundred million years would pack one hundred million megatons of explosive power and turn off the lights. That is, it would cause an extinction event. And Johnson mentioned a near-Earth asteroid known as 2004 MN4 Apophis (later renamed 99942 Apophis), which, as was discussed earlier, is appropriately named after the Egyptian serpent god that is the lord of chaos and darkness. It flies past Earth every seven years and, in 2013, came within nine million miles. The Apophis meteor caused some anxiety in 2004 when it was thought that there was a very slight possibility, soon shown to be wrong, that during its expected approach, it would crash into Earth in 2029. It will come around again in 2036, though astronomers have concluded that it will not be a threat then, either. It is therefore not a dreaded PHA: potentially hazardous asteroid.

  In 2007, the Planetary Society organized a $50,000 competition to design an unmanned probe that would find Apophis and follow it for almost a year, collecting data that could help determine whether it posed enough of a threat to warrant a mission that would deflect it. The society received thirty-seven entries from twenty countries and picked a design called “Foresight” by SpaceWorks Enterprises, a large US firm, which proposed a simple spacecraft that would orbit the asteroid for a month and then follow it around the Sun for ten more months to get enough information about the meteor's trajectory so the likelihood of an eventual impact could be calculated.29

  In January 2013, four years after the meeting in Santa Fe, NASA decided that Apophis will make a relatively close approach in 2029—19,400 million miles—and will swing by again in 2036 at a greater distance, meaning a collision was ruled out. Since the asteroid is 325 meters in diameter, that was very good news indeed, because an impact would cause an explosion in the five-hundred-megaton range.30

  The research presented at the three NRC meetings was duly published in 2010 in a definitive, understandable, and well-illustrated 144-page report titled Defending Planet Earth: Near-Earth-Object Surveys and Hazard Mitigation Strategies that had sections on risk analysis, the survey and detection of NEOs, their characterization by various observation techniques, ways to mitigate the threat, the need (again) for national and international cooperation, and what is required in the way of financial investment. (Ten million dollars a year would allow the current program to continue while, at the other end of the investment spectrum, $250 million annually would buy a robust program with redundant systems that would combine ground- and space-based observation and research on impact techniques for changing the orbit of a threatening asteroid: impacting an impactor, so to speak.)

  “Impacts on Earth by Near-Earth Objects (NEOs) are inevitable,” the report stated at the top of the chapter on mitigation. “The impactors range from harmless fireballs, which are very frequent, through the largest airbursts, which do not cause significant destruction on the ground, on average occurring once in a human lifetime; to globally catastrophic events, which are very unlikely to occur in any given human lifetime, but are probably randomly distributed in time.” The report described the usual mitigation possibilities: slowly pushing or pulling the attacker off course, a kinetic impact that would shove it in another direction, or a nuclear blast that would decisively change its orbit. And in the event that any or all of those mitigation strategies failed, the report advised that a civil defense system be set up to evacuate a region that takes a small but direct hit.31

  What Robert F. Arentz of the Boulder, Colorado–based Ball Aerospace and Technologies Corp., who was on the National Research Council's Survey and Detection Panel warned bears repeating: “It's not a matter of if,” he said, “it's a matter of when.”32

  The prospect of Doomsday, or at least the threat of it, has fascinated people from time immemorial for three fundamental reasons.

  For one thing, preventing it brings out the best of the human species, at least in terms of resourcefulness. Triumph over a formidable opponent is deeply pleasing because it honors and dignifies the human spirit. That is why underdogs who win are celebrated while there are usually no celebrations when overdogs (if they can be called that) are victorious. It is a formula that has always been understood by the coaches of teams that play competitive sports, by writers who craft both fiction and nonfiction stories, and by the producers and writers of war films who have the
heroes suffer physical and sometimes mental injuries before they finally defeat the enemy by dint of sheer courage and reserve strength.

  Then, too, the end of humanity would deprive the universe of wonderful and probably unique creatures (with all their apparent flaws). That makes us feel special and makes our fighting for survival rather than succumbing to extinction of the utmost importance. “Perhaps a sense of impending doom is necessary in certain situations to overcome complacency that might come with a misunderstanding of potential dangers,” Michael Moyer, an editor at Scientific American, has suggested. “If people all over the world had not been overwhelmed by the concern of possible extinction during the Cold War, there may have been a nuclear war with dire consequences. Even now this concern has to be constantly reinforced.”1

  Most religions, on the other hand, assure their followers that belief in a supreme being will bring salvation—as it did to Noah and the creatures on his ark—and that the faithful who suffer will have eternal life, as did Jesus Christ. Death, even when it comes after excruciating pain, is therefore merely physical, not spiritual, and so it can be endured because it ends in immortality.

  Both belief systems—the triumph over death and succumbing to it for spiritual salvation—make the possibility of Doomsday (that is, the end of the world and of all the life on it because of catastrophic destruction) endlessly fascinating. Whether the end can be prevented by bravery and intellect or accepted as the way to gain entry to heaven, it has always captivated a very large segment of humanity and continues to do so. Those people, in the many millions, are an eager audience for writers and others who describe the abiding dangers that threaten our existence and have the characters either fall victim to them but somehow survive anyway or find ways to thwart them, defeat them, by being imaginative, resilient, and heroic.