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

by William E. Burrows

  Prepare an adequate response to the range of potential impact scenarios, including testing innovative deflection technologies in space, assist agencies that are responsible for civil defense and disaster response, research ways to stop NEOs with nuclear and other weapons, and deflect them.

  Provide leadership for the government to address planetary-defense issues with other agencies, in public education, in the news media, and in international forums; to support research in the physical, environmental, and social consequences of a range of attack scenarios; and, with other relevant agencies, to develop a planetary-defense communication plan.

  David Morrison heartily agrees. “For the non-science policy maker, the impact hazard is a complex problem featuring the interactions of physical, technical, and social systems under conditions of great uncertainty,” he has written. “Communications are key, since in the end it is society's perception and evaluation of the hazard that are likely to determine what social and economic resources are applied. Policy makers will be dealing implicitly with the costs of action vs. the costs of inaction. From their perspective, even such an ‘innocent’ first step as the Spaceguard Survey may have substantial social or political costs—for example if frequent ‘false alarms’ persuade the public that scientists are incompetent and are squandering public funds, or if the existence of a survey triggers public demand for more expensive defense systems that decision makers are not prepared to provide.”36

  While the first small steps are being taken by space agencies to stop dangerous asteroids and comets, Morrison has explained, “we are a long way from the technology to deflect an asteroid, especially one potentially threatening to civilization. However, it seems reasonable to expect that if such a large asteroid is discovered, one whose impact could kill a billion people, the spacefaring nations would find a way to deflect it and save the planet. Given such a specific threat, almost any level of expense could be justified. This effort would represent the largest and most important technological challenge ever faced; whether it met with success or failure, world civilization would be forever changed.”37

  Given what is at stake, the ultimate Strategic Defense Initiative to defeat impactors as an integral component of an international planetary-defense system should therefore be a top priority for the world community and would obviously be worth any level of expense.

  That system has been seriously pondered. It is called NEOShield, an excellent name for a peer-reviewed, collaborative, international research program that was started in January 2012 by a handful of science organizations, including the French National Center for Scientific Research and universities in France, Germany, Great Britain, the United States, Spain, and Russia. It is funded in large part by the European Commission, which is the executive body of the twenty-eight-member European Union, a regional unification organization, and is coordinated and essentially led by DLR, the German national space agency. The idea is to study various ways to detect and prevent an asteroid or comet from connecting with Earth and to decide which are the most workable. The research includes laboratory tests and sophisticated computer modeling of what an NEO would do on approach and what techniques would be best for deflecting it. The Boy Scouts famous motto is appropriate: Be Prepared. The participants would like to have a defensive plan in place, should the need arise, rather than have to frantically come up with something quickly as the emergency worsens.

  The three most promising defensive measures seem to be the use of so-called gravity tractors to nudge a potential impactor off course, a kinetic shot to smash it, and explosive blast deflection. (In the most honest of all possible worlds, the last would also be called the Teller Technique, since the explosive blast would have to be nuclear.) The commission's concern about meteorites striking its member states is well founded. People all over Europe, like people everywhere else, have been seeing meteorites and, closer still, meteoroids, streak across the sky since they lived in caves. And in almost every European country, they have collected pieces of the space rocks that were seen to explode into fragments and rain down on their communities. The proof, at least for them, is in the touching.

  “NEOShield was launched in mid-January and, over the next three and a half years, will investigate the measures that can be employed to prevent near-Earth objects such as asteroids and comets from colliding with Earth,” DLR officials have said. Alan Harris, a senior scientist and NEOShield project leader at the German Aerospace Center's Institute of Planetary Research in Berlin, added “The scientific side of this will include the analysis of observational data on NEOs and laboratory experiments in which projectiles are fired at asteroid surface analog materials with different compositions, densities, porosities and structures. We'll be looking in detail at the tricky technical issues associated with autonomous control of a spacecraft in the immediate vicinity of a large, potato-shaped asteroid, and ion thrusters that may have to function continuously and reliably over a period of 10 years or more,” Harris explained.38

  Spotting a potential impactor very far out—at least twenty-five years is most often mentioned—and then pushing it ever so slightly off course so that it misses Earth by a substantial margin is the perfect, optimal strategy, and it is feasible if the asteroid is very far away. But it obviously will not work in a surprise attack, and it is surprise attacks that have marked this planet's experience with NEOs. Every airburst and direct hit has come without warning. But no effective defense can be mounted without a very long warning time. A tracking system with antennas stationed roughly 120 degrees apart around the planet and looking out in all directions, plus Sentinel, should therefore be set up to provide enough warning time so that an effective defensive operation can be undertaken in time to be effective.

  The defensive operation has a theoretical precedent of sorts, though it was for a threat from elsewhere on the planet, not from space. It was the Strategic Defense Initiative—SDI—or Star Wars, as it was called by its many opponents (this author having been an early one)—that was inspired by Edward Teller and that led to President Reagan's famous Star Wars speech on March 23, 1983, and the antiballistic-missile-design stampede that followed for billions of defense dollars. The plan called for Soviet ballistic missiles to be bludgeoned from space as they rose out of their silos and then attacked continuously in their midcourse and terminal phases.39

  Scientists and engineers at some of the national laboratories and in the corporate sector went into a virtual feeding frenzy to come up with concepts that would bring government contracts that Congress set at $44 billion between 1983 and 1993. Lowell Wood invented a nuclear-pumped x-ray laser that would have, in theory, stopped ballistic missiles in midflight by zapping them with very powerful laser beams that came out of hydrogen-bomb explosions. Theory, however, did not translate to fact. The laser did not work. But it was only one among several space weapons that were concocted to stop incoming warheads. The hypervelocity railgun, which was technically the Compact High Energy Capacitor Module Advanced Technology Experiment, or CHECMATE (another GAD award contender), was basically pellets on a rail that were accelerated by an electrical charge to such a high speed that they could drive a bullet through a tank's armor. And researchers devised particle-beam weapons that used high-energy beams of atomic or subatomic particles to destroy a target by damaging its atomic and molecular structure; in effect disassembling it by breaking it up on its most fundamental level. Besides the x-ray laser, there was a chemical laser, space-based interceptors, and even something called Brilliant Pebbles, which were watermelon-sized projectiles that were to be made of tungsten and fired at the missiles from above the way pellets are fired from a shotgun. The missiles were to be spotted and tracked by sensors called Brilliant Eyes. The Strategic Defense Initiative was a profoundly bad idea not only because it was destabilizing rather than stabilizing, but also because the spacecraft that were in permanent orbit and that were supposed to fire the lasers and launch the antimissile missiles were themselves vulnerable to an attack by the Soviets p
rior to the missile fusillade fired at the United States. John Pike of the Federation of American Scientists correctly called SDI a “playpen for engineers.”

  SDI's problem was political not technological. The concept of creating high-tech space weapons to stop a missile attack from elsewhere on Earth was innovative, and it was only infeasible because it was directed against another superpower that could have rained so many nuclear warheads on the United States that an unacceptable number would have hit their targets, destroying not only strategic military installations but also many cities and killing millions. Unless they are directed by intelligent extraterrestrials, that quandary does not exist with NEOs, so a planetary Strategic Defense Initiative using ultra-high-tech weapons modeled on those that were conceived for SDI is not only feasible but imperative. The first-ditch defense should consist of easing a threatening object off course decades before impact with a gravity tractor. Given that distance, nudging it even a couple of centimeters so far out would be sufficient to cause it to miss Earth by a comfortably wide margin. But it is imperative that a last-ditch defense also be in place to stop any impactor larger than 140 meters that is on a collision course with this planet.

  Scientists at California Polytechnic State University and the University of California, Santa Barbara, think so too and have therefore come up with DE-STAR, the Directed Energy Solar Targeting of Asteroids and exploration (yet another contender…), which would convert solar energy into a laser blast that would obliterate any large rocks or icicles bearing down on Earth. “The system is not some far-out idea from Star Trek,” Gary Hughes, a professor and researcher at Cal Poly said. “All the components of the system pretty much exist today. Maybe not quite at the scale we'd need—scaling up would be the challenge—but the basic elements are all there and ready to go. We just need to put them into a larger system to be effective, and once the system is there, it can do so many things.” Philip Lubin, a professor of physics at the University of California, Santa Barbara, added that “our proposal assumes a combination of baseline technology—where we are today—and where we almost certainly will be in the future, without asking for miracles.”40

  There is indeed a consensus that miracles will not be necessary, a point that echoes Gene Shoemaker's observation about the difference between earthquakes, hurricanes, volcanoes, and other natural disasters that are generated on this planet and objects that come from elsewhere. The former cannot be controlled (at least not yet). The latter can.

  There is complete agreement among the most sagacious that planetary defense starts with knowing precisely what is out there and where it is headed. As would be expected, the master tome on the subject, Hazards Due to Comets and Asteroids, was published by the University of Arizona Press in 1994. One of its chapters, written by David Morrison, Clark Chapman, and Paul Slovic (of the University of Oregon), described the impact hazard in considerable detail and concluded, as do their colleagues, that the largest “projectiles” have to be dealt with first and that the means to do so requires a comprehensive survey of Earth-crossers such as has been accomplished by the Spaceguard Survey. “Better understanding of the numbers, orbital distributions, and physical properties of asteroids and comets are required in order to define an effective defense system,” they note.41

  Then there was some significant progress in literally sizing up the problem. In August 2002, NASA was so pleased at the progress that was being made by the Spaceguard Survey to find and catalog 90 percent of Near-Earth Objects a kilometer or larger in diameter that it chartered a Science Definition Team to study the feasibility of extending the search for NEOs to those smaller than a kilometer. The team, whose twelve notable members included Yeomans, Robert S. McMillan, and Simon P. Worden, deliberated for a year and issued an important 154-page report in August 2003 that made three recommendations: (1) goals related to the search for potential impactors should be stated explicitly in terms of the statistical risk that would be eliminated and should be based on the standard cost/benefit analysis, (2) an NEO search program should be started that would discover and catalog the potentially hazardous “population” so precisely that 90 percent of objects smaller than the kilometer threshold (i.e., Earth threatening) would be eliminated, and (3) an announcement of opportunity should be released that would allow any individual or organization interested in developing the discovery and cataloging program to make specific recommendations.42 That is Sentinel's assignment. Where planetary defense is concerned, it is literally a giant step in the right direction.

  “The Earth is so small and so fragile and such a precious little spot in the universe that you can block it out with your thumb,” Rusty Schweickart has said. “And you realize on that small spot, that little blue and white thing, is everything that means anything to you—all of history and music and poetry and art and death and birth and love, tears, joy, games, all of it on that little spot out there that you can cover with your thumb. And you realize from that perspective that you've changed, that there's something new out there, that the relationship is no longer what it was.”

  Gene Cernan echoes that. “You…say to yourself, That's humanity, love, feeling and thought. You don't see the barriers of color and religion and politics that divide this world. You wonder if you could get everyone in the world up there, would they have a different feeling?”1

  Their view of Earth as a solitary island of precious life in a dark and foreboding universe, an incubator of creatures with infinitely complex intellects and emotions, is shared by everyone who has gone to the Moon and by space scientists like Carl Sagan, who characterized it as a pale-blue dot to be cherished and protected.

  That's not the way Osepok Tarov sees it, though. She is the commander of a multigenerational intergalactic spaceship that has left Earth and is heading for some place very far away to start a colony in Buzz Aldrin and John Barnes's epic science fiction novel Encounter with Tiber. Earth, she has decided, has become so spoiled that it is no longer a fit habitat for humans. “They found forest fire ashes, evidence of earthquake collapses, layers of volcanic ash, all kinds of things in the area,” Osepok tells her crew to justify leaving the home planet. “We might have started here, but it was a tough place to stay alive. So we spread out—down the rivers, up into the hills, across the plains, eventually over the seas to Shulath—and now out into space. There's not a place in the universe that's safe forever; the universe is telling us, ‘Spread out, or wait around and die.’”2

  When Osepok thought about the danger of living on Earth, though, it was not just forest fires, earthquakes, and volcanoes she had in mind. It was The Intruders and the “bombardments” they caused. “The Intruder shattered into billions of pieces of all sizes, scattering into a great cloud. Thus, although the dense central part of the cloud missed our world by a wide margin, the debris—abundant even in the thin edges of the cloud, the biggest pieces the size of mountains, most boulder-sized or smaller—had sprayed our world, and Sosahy, in what the history books called the First Bombardment. The First Bombardment had been bad enough; one out of eight people worldwide killed, and Shulath wrecked. The Second Bombardment would finish off Nisu. One hundred and forty-some years in the future, there would be nothing left of us—unless some of us, somehow, could be somewhere else.”3

  Robert Shapiro, a brilliantly imaginative professor of chemistry at New York University, was not a fatalist about Earth, but he also believed that it is prudent to spread out. That is why he conceived of the idea of maintaining a continuously updated record of the home planet's civilizations at either pole and on the Moon so that if a catastrophe occurs, what happened to all the papyruses when the Great Library at Alexandria was destroyed will not happen again. “No skipper goes to sea thinking his boat is going to sink,” Shapiro told the author, “but he carries a dinghy, life preservers and insurance just in case.”4

  The Moon is Earth's dingy—a seaworthy habitat that can help assure the survival of life if the mother ship is attacked or founders—but it is rarely seen
that way. It has traditionally been considered to be the first stop in the exploration of the Solar System and beyond in what would be the greatest adventure in history, the first off-planet staging area in a great migration to space by a race of creatures that is genetically programmed to explore, to seek new worlds, in the tradition of Magellan, Columbus, Cortez, da Gama, Cheng Ho, and ibn Battuta.

  That is what Jules Verne had in mind when he penned From the Earth to the Moon and its sequel, Around the Moon. The latter of the two was published in 1870 and, in it, three members of the Baltimore Gun Club—Barbicane, Ardan, and Nicholl—are shot out of the giant Columbiad cannon to scout the Moon for signs of a past civilization and to reconnoiter it for future habitability. (The cannon was necessary because it would be thirty-three years before Konstantin Eduardovich Tsiolkovsky, a rural Russian school teacher, published the seminal “Exploring Space with Reactive Devices” in the Scientific Review, which established liquid rockets as a viable propulsion system. Ironically, he was inspired to invent the liquid-propelled rocket, which developed far more thrust than the Chinese type that ran on powder like their famous fireworks, by reading Verne.)

  Sure enough, the three adventurers see signs of an ancient civilization as they pass over the lunar surface, and Barbicane becomes convinced that humans could, with great difficulty, make the Moon habitable again.

  “My friends,” said Barbicane, “I did not undertake this journey in order to form an opinion on the past habitability of our satellite; but I will add that our personal observations only confirm me in this opinion. I believe, indeed I affirm, that the moon has been inhabited by a human race organized like our own; that she has produced animals anatomically formed like the terrestrial animals: but I add that these races, human and animal, have had their day, and are now forever extinct!”5