Asteroid Threat : Defending Our Planet from Deadly Near-earth Objects (9781616149147) (6 page)

By the start of the last decade of the twentieth century, Congress had become sufficiently concerned about the impact threat, so it mandated NASA to locate within ten years 90 percent of NEOs with diameters of a kilometer or more. Then, in 2005, Congressman George E. Brown of California, whose constituents included several aerospace companies, led a campaign that expanded the number of potentially threatening intruders the space agency had to locate and catalog to 90 percent of those that measured 140 meters or larger by 2020 (as in perfect vision). But the Obama administration did not ask for funds to complete that task, and the concern that was dramatically proclaimed in Congress did not extend to authorizing enough of an appropriation to do the necessary work. As has been ruefully noted for a very long time, the members of the House of Representatives seem to have attention spans that are limited to two-year election cycles. The space agency therefore had to try to carry out its mandate with restricted funds. It was like a modern farmer being ordered to produce a bumper crop using only a plow pulled by a mule.

But two usable crops—that is, studies—were harvested. The first, titled
Asteroid and Comet Impact Hazards
and conducted by the Spaceguard Survey Report, was released in 1992. The second,
Report of the NEO Survey Working Group
, came out three years later. The Spaceguard Survey Report owes its name to Arthur C. Clarke, who invented the term and used it as the title of
chapter 1
in his
Rendezvous with Rama
: “SPACEGUARD.” So too does the concept behind the report owe itself to Clarke: it made the obvious point that defense against asteroids and
comets depends on understanding their nature—that is, their size, their composition, their velocity, their location, and the direction in which they are moving. The Spaceguard Survey Report ranked the potential impactors' destructive capacity according to size, which translated to “kinetic energy.” Smaller ones—those with less kinetic energy—approach Earth more frequently than their larger counterparts but inflict little or no damage. The bigger ones come in less frequently, but when they do, they can inflict severe damage. And coastal populations are at greater risk than inland populations because of tsunamis. “Persons living in coastal regions,” the report warned, “run a risk from impact-generated tsunamis as much as two orders of magnitude greater than that from land impacts.”
³⁴

As the Spaceguard Survey Report was accepted and began to take hold within the space community, so did the effect of an important paper that was published in February 2001 that brought the planetary-defense situation around full circle.
The Comet/Asteroid Impact Hazard: A Systems Approach
was written by Clark R. Chapman, Daniel D. Durda, and Robert E. Gold, three leading space scientists. Chapman and Durda were in the Department of Space Studies at the prestigious Southwest Research Institute in Boulder, Colorado, and Gold was in the equally prestigious Space Engineering and Technology Branch of the Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland. They maintained that the danger of a serious impact was potentially so great that an integrated approach to the problem across the scientific, technological, and public-policy sectors was fully justified. While the emphasis at that point had been on astronomers spotting potential impactors and finding ways to deflect them, the authors contended that little or no thought had been given to connecting the astronomers with the military and civilian agencies that would be responsible for pushing approaching NEOs off course; to planning other kinds of mitigation and dealing with the repercussions
of predicting an impact (mass civil panic, for example); and to the need for an informed, international effort to actively plan a mitigation strategy that would replace what they derided as “unbalanced, haphazard responses.”
Mitigation
in the NEO community means “to stop the threat.” “For example,” the authors contended, “we believe it is appropriate, in the United States, that the National Research Council develop a technical assessment of the impact hazard that could serve as a basis for developing a broader consensus among the public, policy officials, and government agencies about how to proceed. The dinosaurs could not evaluate and mitigate the natural forces that exterminated them, but human beings have the intelligence to do so.”
³⁵
Then, poignantly, they took note of the seed that had been planted two decades earlier:

The scientific community began to understand the implications for life on Earth of errant small bodies in the inner Solar System in 1980 when Nobel Laureate Luis Alvarez and his colleagues published an epochal paper in
Science
(Alvarez et al. 1980) advocating asteroid impact as the cause of the great mass extinction 65 million years ago that led to the proliferation of mammal species based on an extraordinary discovery they made at the Chicxulub impact crater underwater off Yucatan on Mexico's gulf coast.
³⁶

The National Research Council, which is part of the prestigious National Academy of Sciences, was paying attention, and so was the rest of the international space-science community. In October 2002, Chapman met with former astronauts Russell L. “Rusty” Schweickart and Ed Lu, as well as Piet Hut, an astrophysicist at Princeton's Institute for Advanced Study who specialized in planetary dynamics (specifically in preventing asteroid impacts). They gathered at the Johnson Space Center and hatched the B612 Foundation, which was named in honor of the little prince who lived on the asteroid. The foundation's purpose was to protect Earth from asteroid strikes by funding the development of ways to deflect them.

In February 2000, a far-ranging space probe called the Near-Earth Asteroid Rendezvous Shoemaker (NEAR Shoemaker) was ordered to fly in close formation with a thirty-three-kilometer-long, thirteen-kilometer-wide, potato-shaped asteroid named 433 Eros for a year, collect data as it went, and then land on it. Eros, as in
erotic
, is the god of sex and making love in Greek mythology. NEAR Shoemaker's controllers, who, like many in the space program, had a sublime sense of wit and irony, ordered it to mount Eros on February 12, 2001. It was therefore on Eros two days later, which was Valentine's Day.

The next step in planetary protection was a big one, and it happened at the Hyatt Regency Hotel in Garden Grove, California, from February 23 to 26, 2004, when the National Research Council held the first international Planetary Defense Conference. The conference was dedicated to “Protecting the Earth from Asteroids”
³⁷
and was precisely what Chapman, Durda, and Gold had called for three years earlier in
The Comet/Asteroid Impact Hazard: A Systems Approach
.

Eighty-one papers were presented at that meeting on topics such as “Order-of-Magnitude Analyses of Planetary Defense Problems,” “Orbit Determination for Long-Period Comets on Earth-Impacting Trajectories,” “The Impact Imperative—A Space Infrastructure Enabling a Multi-tiered Earth Defense,” and “The Mechanics of Moving Asteroids.” In addition to heavy participation by Americans, scientists from Russia, Italy, Ukraine, Bulgaria, Spain, South Korea, France, Germany, and India came to make presentations.

At about the same time, and unrelated to the meeting, David Morrison began sending out
NEO News
on the Internet, and it subtly but effectively helped to bring the NEO community together. And a galaxy of astronomers and others who were interested in the impact threat began to coalesce as a separate group.

The reach of Morrison and several other astronomers soon extended to Europe. On March 26, 1996, the Spaceguard
Foundation was established in Rome with the declared intention of protecting “the Earth environment against the bombardment of objects of the solar system (comets and asteroids).”
³⁸
Its members were mostly European, of course, but included a Japanese scientist on its board of directors. And the foundation's two trustees were definite attention-getters. The first is Fred Whipple, a very well-known astronomer. The second, none other than Arthur C. Clarke, who was billed as the author of “several famous science fiction novels, including…
2001: A Space Odyssey
(1968); in
Rendezvous with Rama
(1973) he described the effects of the collision of an asteroid with the Earth and the settlement of a
Spaceguard
organization for the protection of the Earth against such events.”
³⁹

Then the European Space Agency weighed in. In April 2006, it announced that it planned to “slam” an impactor probe into an asteroid in a mission it wryly called Don Quijote. The mission was to involve two spacecraft: one named Sancho that would orbit the asteroid and study it for several months, and a second, Hidalgo, that would collide with it. Then Sancho was to return to the asteroid to assess the damage and report home.

The mission was originally scheduled for 2011; then it was postponed to 2015. And then, in late December 2009, Anatoly Perminov, the head of Roskosmos (the Russian space agency), declared that he was considering inviting the international community to send out a robot to meet a large asteroid named Apophis that is headed in this general direction and to nudge it off course before it makes its first pass by Earth in 2029. He was referring to 99942 Apophis. The huge rock takes its name from an evil ancient-Egyptian serpent that dwelled in eternal darkness in the center of Earth. No professional astronomer seriously believes that Apophis is going to hit this planet the first time around, but there is some concern that it, too, will be ensnared by Earth's gravity and swing into an orbit that becomes increasingly closer until it impacts.
⁴⁰

The possibility of Earth attracting a potential impactor came to mind on June 6, 2002, when the Eastern Mediterranean event took place. Yet another meteor exploded in the sky between Libya and Crete, without warning and with the power of a small atomic bomb. It happened during the 2001–2002 India-Pakistan confrontation, and, in the opinion of Gen. Simon P. Worden, vice director of operations for the US Space Command, had it occurred three hours later, it could have caused a nuclear war between the two enemies.
⁴¹
Either side could have thought the explosion was caused by a ballistic missile that had been launched by the other side, blowing up prematurely, or that it was meant to knock out the other side's communication capability as a prelude to a nuclear war. Seen in that light, the name
impactor
takes on two distinct and dangerous meanings. They are, of course, physically dangerous. But to the extent that they can trigger war or other forms of manmade violence, they are abidingly dangerous politically as well.

“So it is said that if you know others and know yourself, you will not be imperiled in a hundred battles,” Chinese warrior-philosopher Sun Tzu wrote more than two thousand years ago in his classic work,
The Art of War
.
¹
“Others” is often translated as “enemies,” which is precisely what he meant. “Know thine enemy” is a widely used variation on the theme. And since there are an infinite number of others—enemies—in this world, the advice is universally applicable to individuals and to the multifarious relations between nations.

There are also infinite enemies out of this world, and knowing all about them—what they are, where they are, and where they are going—could make the difference between this planet's safety and survival and its either suffering a severe wound or being annihilated altogether. The early Greeks and Romans saw that rocks fell from the sky and pondered its meaning. Aristotle was convinced that they were first lifted off Earth's surface by strong winds and were then thrown back. He and Pliny the Elder are thought to have both written about an impact that occurred in 467 BCE, when a meteorite fell on Aegospotami in Thrace, on the European side of the Dardanelles. And a comet was seen the same year.
²

“Thunderstones” were held in awe and venerated as thunderbolt weapons that were hurled at this world by angry gods. In his book
Natural History
, Pliny wrote that a comet appeared in 44 BCE just after Julius Caesar was assassinated and during athletic games he had sponsored. Pliny reported that it was seen
everywhere as a bright star in the north for seven days. It was widely believed that the comet was the soul of Caesar on its way to the sanctum, where the immortal gods lived. The emblem of a star was therefore added to a bust of the slain emperor that was dedicated in the forum.
³

Comets soaring across the night sky, trailing their long luminescent tails, excite us because we take them to be elegant visitors from the infinite, black universe—space—that engulfs us. (And since
vacuum
is defined as a place absolutely devoid of matter, it does not apply to space, which is full of stars, planets, moons, asteroids, comets, and all manner of cosmic debris that are the size of pebbles and grains of sand.) But that take is new and is the product of modern astronomy. For centuries, comets were taken to be fiery messengers, flaming arrows, that were shot at Earth from angry gods. Unlike sunrise, sunset, the stages of the Moon, and other celestial occurrences, comets were unpredictable, and that caused widespread fear and superstition among people who found security in the predictability of nature. The sudden appearance of a comet was taken to be a harbinger of doom; a message from their god, who was angry and warning that a war, a natural disaster, a plague, a famine, or some other catastrophe was imminent. The Babylonian
Epic of Gilgamesh
, the most ancient surviving myth, warned that a comet would bring fire, brimstone, and a flood. The Sibylline Oracles, who were Roman prophets, referred to comets as a “great conflagration from the sky, falling to earth.”
⁴

Chinese astronomers as early as the Han Dynasty kept extensive records on the appearances, paths, and disappearances of hundreds of comets and associated different shapes with specific disasters.
⁵

The beginning of serious, modern astronomy that started when Copernicus decided that the Sun, not Earth, was the center of this planetary system took a colossal leap forward when Galileo began peering through that first telescope—a
long, narrow, wooden tube that was covered with paper and had a small lens at either end—in 1609. Myth was replaced by hard reality, and a revolution started that slowly but surely gained momentum as more of the devices were built and used by men who were enthralled to be able to finally get much closer views of the heavens; to, in effect, get off here and go out there. One of them was Johannes Kepler, a German astronomer and astrologer (they were often considered indivisible) who used his celestial magnifier to study planets and then published the three laws that describe their orbits and that bear his name.

One night in 1682, seventy-three years after Galileo trained that crude cylinder on the Moon's battered surface, a twenty-six-year-old Englishman named Edmond Halley who had a deep interest in natural science, including oceanography and meteorology, in addition to mathematics, noticed a comet flash across the sky and instinctively began plotting its positions when it reappeared on successive nights. In August 1684, he visited the University of Cambridge to see an obscure professor named Isaac Newton. Halley told Newton about the frustration he and some friends had had in trying to understand the force that kept the planets traveling around the Sun and that grew weaker with distance. Objects moved faster when they were closer to the Sun, Halley explained, and slower when they were farther away.

“I have calculated it,” Newton told Halley. “I worked it out seventeen years ago. I wrote the full solution down five years ago. It's around here someplace,” the genius told his visitor. Then history's most famous absent-minded professor shuffled through some papers.

“You can't be serious,” said Halley. “You explained the force that controls the planets and you never told anybody about it?”

“It explains the Moon in orbit around the Earth and the tides also. And how dropped objects fall to the ground. Let's see. I think I put it in this drawer. No, not here, either,” the man
who conceived the law of universal gravitation told his awed visitor.
⁶

It was eventually calculated that the comet Halley had noticed and then took pains to plot returned every seventy-six years and, because of its brightness, it (like other comets) was seen, tracked, and studied. In keeping with tradition, the comet Halley studied so intently was named after him. And sure enough, as predicted, it returned on Christmas night in 1758, sixteen years after the man who immortalized it had passed on. It last crossed Earth's path in February 1986, and astronomers were able to see that it is made of water ice, carbon monoxide, carbon dioxide, ammonia, methane, various other chemicals, and some iron. It was appreciated by Earthlings who understood that they were witnessing what for almost all of them was a once-in-a-lifetime event that was savored. It is due back in 2062.

Astronomers and space scientists certainly appreciate comets for their appearance, but these are the people on the most-wanted list of those responsible for “mitigating” comets' potential to do terrible damage on impact; that is, they are in charge of finding and stopping a comet before a collision that is bound to be terrible. That is why Clark Chapman, Daniel Durda, and Robert Gold wrote
The Comet/Asteroid Impact Hazard: A Systems Approach
. Their concern was shared by many in the space community, who organized the groups that are described in
chapter 5
: “The Other Salvation Army.” Scientists, including Gene Shoemaker, Clark Chapman, Donald Yeomans, Steven J. Ostro, Jon D. Giorgini, and David Morrison (a stalwart among the near-Earth-object fraternity who is at the NASA Ames Research Center in Northern California), have found comets so interesting that they specialized in studying them. Yeomans, as noted, was at NASA's Jet Propulsion Laboratory (JPL), where he headed the Near-Earth Object Program Office; so were Ostro and Giorgini. JPL ran most of NASA's Solar
System Exploration Program in the 1960s and '70s, most notably Voyager 1's encounter with Jupiter, Saturn, and several of their moons and Voyager 2's phenomenal “Grand Tour” of Jupiter, Saturn, Uranus, Neptune, and many of their moons. It is important to note that, in addition to sending home a veritable library of new scientific information about those distant worlds—that Jupiter's moon Europa has an active volcano; that the planet's fabled rings are made of an infinite number of rocks of all sizes and pebbles; and that Neptune has rings, too—the stream of imagery that came back to JPL from every close encounter with a solid body showed impact craters that were made by collisions with asteroids of all shapes and sizes. It was the pockmarked moonscape, the eternal target of sheer violence, repeated infinitely. The wandering rocks themselves, which were known to be an important cause of destruction in the Solar System, were studied with obsessive interest by many astronomers and planetary scientists, who then produced hundreds of scholarly papers and books, such as
Comet/Asteroid Impacts and Human Society: An Interdisciplinary Approach
edited by Peter T. Bobrowsky and Hans Rickman and
Asteroid: Earth Destroyer or New Frontier?
by Patricia Barnes-Svarney.

The ubiquitous (and mellifluous) astronomer Carl Sagan, who was unfairly denounced by some members of scienceworld for being a dreaded “popularizer,” wrote
Comet, Revised
with Ann Druyan, which was published in 1997. Two chapters were devoted to asteroids and comets hitting Earth and other targets and featured a ride on one (possibly sending a message to Michael Bay, Jerry Bruckheimer, Bruce Willis, and the rest of the cast and crew of
Armageddon
, which was released the following year). That was followed by
Cosmos
, a book that became the television series that made Sagan famous. Yeomans and three colleagues published
Mitigation of Hazardous Comets and Asteroids
in 2004, and he wrote
Near-Earth Objects: Finding Them before They Find Us
, a serious, readable primer
on the subject (and on space in general), almost a decade later. And Duncan Steel, an Australian astronomer, weighed in with
Rogue Asteroids and Doomsday Comets: The Search for the Million Megaton Menace That Threatens Life on Earth
.

Not to be left out, a Russian astronomer and one from Belarus weighed in with news about a huge comet that came out of the Oort Cloud, which is believed to envelope this Solar System and sends in every comet. This large comet, they predicted, will visit the neighborhood but not pose a threat to Earth. It is variously called Comet C/2012 S1, Comet ISON (for the International Scientific Optical Network, one of whose telescopes was trained on it), and Nevski-Novichonok for the two men who discovered it.

On at least one occasion, the dramatic specter of a comet streaking across the sky like a shot from God's sling caused a bizarre tragedy. The comet was Hale-Bopp, which was discovered in July 1995 by two independent American sky watchers after whom it was named: Alan Hale and Thomas Bopp. It caught the attention of the public when it became a spectacular sight as it passed Earth at distance of only seventy-six thousand kilometers in March 1997 and was acclaimed the Great Comet of 1997 by millions of people around the world who could see the spectacular show it put on just by looking at it without telescopes.

Thirty-nine of those who looked up lived in San Diego and belonged to a doomsday religious cult called Heaven's Gate, which was founded in the early 1970s by a recovering heart-attack victim named Marshall Applewhite and his nurse, Bonnie Nettles. Both Applewhite and Nettles believed that Earth was about to be recycled, which is to say wiped clean of the creatures that lived on it and then renewed. The two claimed to be from “somewhere else” in the literal, not figurative sense—extraterrestrials—and insisted that the only way to avoid the apocalypse and find salvation at the Next Level (of existence)
was to shed every attachment to the planet, starting with ending all relationships with others, including family and friends, and forgoing individuality, jobs, possessions, money, and sexuality so their spirits would not be encumbered by earthly baggage for the voyage to the Next Level. The cult rented a 9,200-square-foot mansion in a gated, up-scale community and spent $10,000 on alien-abduction insurance to cover up to fifty people. Hale-Bopp became visible to the naked eye in May 1996, and the leader of Heaven's Gate was soon telling his devoted followers that the comet was being followed by a UFO that would transport their spirits to the Next Level, but only if they shed the excess baggage they called their bodies. The followers did that by swallowing phenobarbital, cyanide, and arsenic and washing them down with vodka over the course of three successive days, with one group carefully laying the “embarked” deceased in their own bunk beds, their faces and torsos covered with a square purple cloth, before it took its turn with the poison. All thirty-nine decomposing corpses were dressed in identical black shirts and sweat pants, wore armband patches that said “Heaven's Gate Away Team,” and carried a five-dollar bill and three quarters, which they apparently believed was the toll that had to be paid to get to the Next Level.
⁷
Such is the often-perverse romance of comets, however dangerous they can be.

Monster asteroids are far more dangerous than comets because the latter are relatively soft and there are far fewer of them. The little prince may have loved the asteroid he lived on, but the rocks that roam inside the Main Belt and randomly cross Earth's path do not inspire affection from most of the planet's inhabitants, especially those who know firsthand what they do as meteorites, meteoroids, or bolides, as they are called when they get closest to Earth. (Bolides are loosely defined as fireballs.) Ask anyone in Chelyabinsk. One colossal object—a projectile roughly the size of Mars—is thought to have smashed into Earth during its formative stage with such force—a “giant impact”—
that it knocked off a chunk that became the Moon. The author of a book on that subject gave it a title that is as vivid as it is imaginative:
The Big Splat
.
⁸
Earthlings don't like and, indeed, fear asteroids because it is they, not comets, that have had the overwhelming number of collisions with this planet.