Editors’ Note: The Summer 2014 issue of California magazine is called “This is the End.” Every day this week: a different catastrophic scenario.
It started with a flash.
At a few minutes past 9:00, one crystalline morning last February, a burst of light brighter than 30 suns illuminated Chelyabinsk, Russia, a southern industrial city known mostly for making tractors. Thanks to smartphones, surveillance cameras, and Russian auto-dash cams, we have a voluminous record of what happened next.
As the glow faded, a fireball the size of a six-story building blazed across the northern sky. It hit the atmosphere going Mach 50, fueled by the energy of more than 20 Hiroshimas and trailing a dirty-white plume. In a cameraphone video from that morning, a few men stood in the snow gawping at the fireball above their heads.
“What do you think?” one guy asked, more curious than afraid. “Maybe it was a satellite? Sputnik?”
Then the shockwave hit. The cameraman screamed and the picture spun wildly as the earth shook beneath his feet. The blast knocked people to the ground and burned the skin off others. Car alarms blared for miles around. Closed-circuit video feeds showed windows blowing inward, walls collapsing, people huddling under desks. Flying debris cracked open a statue of Alexander Pushkin in a library. There were no deaths, somehow, but 1,500 were injured. Eight months later, researchers pulled a half-ton chunk of the asteroid out of a frozen lake more than 40 miles from the city.
Nobody had seen it coming. This “near-Earth object,” as scientists have dubbed such asteroids, emerged from the direction of the sun, rendering it all but invisible to ground-based telescopes.
The visitation was a reminder that, at some point, an asteroid measured better in miles than feet will come for us all. According to a 1994 study published in the scientific journal Nature, we stand a 1-in-40,000 chance of dying in a “cosmic impact.” That’s more likely than perishing in a tornado, and less likely than in an airplane crash. At least in theory, the world possesses the technology to both detect and counter this threat. But as things stand right now, the next big impact might play out much as Chelyabinsk did: a short, sharp, and entirely unexpected shock—only with casualties in the millions or even billions.
Franck Marchis, a former UC Berkeley astronomer who is now a principal investigator at the SETI Institute in Mountain View, says “It won’t happen tomorrow. But it will happen. It’s a matter of time.”
It has happened before. Our corner of the universe is choked with millions of asteroids large and small—early astronomers referred to them as “vermin of the skies.” Composed of smashed-together rock and metal, they are the remnants of our solar system’s formation 4.6 billion years ago, like leftover rebar and concrete at a construction site. They travel through space according to their own particular gravitational logic. Marchis, who had an asteroid named for him in 2007, likens the arrangement to billiard balls on “a gigantic pool table.” Thankfully, most of these asteroids never come anywhere near the Earth. Inevitably, though, the orbits of some of them intersect with ours. Most of them burn up upon entering our atmosphere, too small to do major damage. But there are exceptions.
The largest impact in modern history occurred in 1908, when a 120-foot-wide asteroid (or perhaps a comet; it’s tough to say without a visual record) wiped out more than 800 square miles of forest near the Podkamennaya Tunguska River in Siberia. Due to Tunguska’s isolation, the blast killed mostly trees and reindeer, but it was big enough and hot enough to have flattened the San Francisco Bay Area. In a village 280 miles from ground zero, an Irkutsk newspaper reported that peasants “ran into the street in a panicky fear, old women cried; everyone thought that the end of the world had come.”
Almost 4,000 miles to the west, the sky over England that night was “a delicate salmon pink,” according to one observer. “I myself was aroused from sleep at 1:15, and so strong was the light at this hour, that I could read a book by it in my chamber quite comfortably.”
NASA says it has located 93 percent of “planet-killer” asteroids and is expected to find the rest of them by 2020. But that still leaves potential “city-killer” asteroids.
The full extent of the threat of cosmic impacts did not become apparent until 1980, when UC Berkeley’s Luis Alvarez, a Nobel Prize-winning physicist, and his son Walter, a Cal geologist and Big History pioneer, discovered that a clay layer in the Earth’s crust corresponding to the dinosaurs’ great die-off 65 million years ago was packed with iridium, a metal common in space rocks but exceedingly rare down here. They theorized that an asteroid (or comet) larger than Mt. Everest hit Earth with the force of the world’s entire nuclear arsenal, spawning a devastating tsunami and inferno-like temperatures, and blotting out the sun with soot. Within a few months, 75 percent of the world’s species were extinct. As Walter Alvarez wrote in his book on the subject, T. Rex and the Crater of Doom, “Earth would suffer cataclysmic damage in less time than it takes to read this sentence.”
The Alvarez theory was controversial but compelling, and 11 years later, the discovery of the Chicxulub crater—a yawning, 110-mile-wide depression in the Yucatán Peninsula—seemed to confirm what most experts already accepted: It was an asteroid that wiped out the dinosaurs. As if to underscore the point, in 1994 the comet Shoemaker-Levy 9 barreled into Jupiter, triggering pyrotechnic mushroom clouds and gouging massive holes in the planet’s surface.
Fortunately, scientists estimate that an extinction-size asteroid (larger than 1 kilometer, give or take) only comes along every 500,000 years. NASA says it has located 93 percent of such “planet-killers” and is expected to find the rest of them by 2020.
That still leaves potential “city-killer” asteroids like the one that hit Tunguska, which strike roughly once a century, unaccounted for. NASA’s best guess is that we have found a mere 1 percent of those, which means there are still roughly 10,000 undetected out there. Spotting such smaller-but-still-dangerous asteroids is difficult—they are, basically, black rocks hurtling through the vast blackness of space—and requires satellite telescopes. And those satellites in turn require big money, which is in short supply since the end of the Space Race, the Cold War–era competition between the United States and the Soviet Union for dominion over the heavens. As Marchis puts it, “NASA does not have anything under control. We just don’t know what’s out there.”
The month after the Chelyabinsk event, Congress held a hearing, Threats from Space: A Review of Private Sector Efforts to Track and Mitigate Asteroids and Meteors, Part II. It was a sober affair. NASA Administrator Charles Bolden estimated it would take his agency until 2030 to locate 90 percent of the city-killers. The committee chair, Texas Republican Lamar Smith, smiled tightly and said, “That’s not particularly reassuring.”
The international community isn’t doing any better. The United Nations convened an asteroid task force in 2008, bringing together an all-star team of astronauts, astrophysicists, and other experts. Based on the group’s recommendations, the UN is stitching together an ad hoc system of existing telescopes (grandly dubbed the International Asteroid Warning Network) to share data. It is also developing a blueprint for international cooperation to hammer out who would lead the response effort if an incoming asteroid is found. Again, the missing ingredient in these plans is money.
“This isn’t an astronomy problem,” says Karlene Roberts, a professor at the Haas School of Business who contributed her expertise in management and organizational behavior to that UN task force. Given the proper funding, we can find them, she says. “The biggest challenge is getting the world to agree that this is important.”
Ed Lu, a three-time astronaut, research scientist, and former adviser to Google’s philanthropic arm, also served on the task force. He chalks up the glacial progress to human nature. “The tragedy of the commons: When it’s everybody’s problem, it’s nobody’s problem.” With that in mind, Lu cofounded the Silicon Valley-based B612 Foundation (a nod to the asteroid in Antoine de Saint-Exupéry’s The Little Prince), a nonprofit with an admirably straightforward motto: Defending Earth Against Asteroids.
Aiming to find the city-killers missed by the world’s space agencies, B612 is overseeing the construction of a satellite named Sentinel. Outfitted with an infrared telescope suited to spotting the dark rocks, Sentinel’s orbit around the sun will allow it to detect asteroids like Chelyabinsk that ground-based telescopes don’t see.
The project, set for a 2017–18 launch atop a rocket made by SpaceX, the private space service started by Tesla cofounder Elon Musk, is bypassing the government entirely. An estimated $450 million price tag—a little less than the Air Force expects to shell out for each of its next-generation bombers—will be paid for Valley-style, through private fundraising. Going the private route wasn’t an ideological choice, Lu explains. It’s just that no one else was doing it. “We’re the only ones taking it seriously.”
The film Armageddon provided an inadvertent illustration of how not to save humanity. UC Berkeley physicist Richard Muller remembers yelling at the screen as he watched. “They were saying, ‘Let’s blow that thing to smithereens!’ And I was shouting, ‘They’ve got it all wrong!’ ”
Once the world has a handle on the size of the threat, it can get to work on solutions, most of which involve nuclear weapons. Edward Teller, father of the H-bomb and patriarch of Lawrence Livermore National Laboratory, advocated a space-based nuclear defense system against asteroids. That idea never took off, but scientists are pursuing approaches that would ram nuclear payloads into oncoming asteroids. With sufficient warning—months or years, depending on the size of the asteroid—the nukes could nudge a rock out of its Earth-bound trajectory.
There are potential drawbacks, however. For one, nuclear weapons might simply break a dreadnought asteroid into smaller, irradiated chunks that would still hit Earth. Armageddon, the big-budget 1998 film in which Bruce Willis leads a team of oil drillers into space to nuke an oncoming asteroid, provided an inadvertent illustration of how not to save humanity.
Richard Muller, the Berkeley physicist whose book Nemesis posited the existence of a companion star to the sun responsible for launching the space rock that killed the dinosaurs, remembers yelling at the screen as he watched. “They were saying, ‘Let’s blow that thing to smithereens!’ And I was shouting, ‘They’ve got it all wrong!’”
So, what alternatives are there? Ed Lu coauthored a study exploring the use of a “gravity tractor”—an extremely heavy spaceship that would fly alongside an asteroid and, using the ship’s mass, gradually alter the course of the rock. Bear in mind, it wouldn’t work as a last-minute solution. The authors calculated that, given a 20-year lead, it would take a 20-ton tractor a year of towing to deflect a 200-meter asteroid.
Thankfully, there doesn’t appear to be anything menacing on the horizon for at least the next 100 years. Lu, however, reminds me that we don’t have a full picture of what’s out there. “That’s the urgency,” he says. “We just don’t know.” He compares an asteroid strike to preventable disasters such as Hurricane Katrina. “They knew the levees weren’t up to snuff, but they did nothing,” he says. “If we get hit, that’s not bad luck. That’s a choice.”
Meanwhile, if we’re inclined to worry about the end of the world, where should asteroids rank on the list? Muller says it depends. Probability, after all, is a funny thing.
“We’re small targets, and the Earth has a lot of empty space.” Then again, he adds, “the big ones that’ll devastate the whole Earth? There’s no hiding from them. Just ask the dinosaurs.”
Chris Smith, M.J. ’01, regularly writes for California. Two of his articles garnered Gold Awards from the Council for the Advancement and Support of Education in 2013.