was right. The sky really is falling. Maybe not today or tomorrow. And not necessarily on you. But eventually, and without a doubt, a big hunk of space junk will fall out of a bright blue sky and ruin our collective day. A hard rain is gonna fall.
Big meteorites are the cruel trick that space plays on life. Like the kid at playschool that waits until you have painstakingly built the Lego city and then smashes it to the ground. Evolution is the slow process of accumulated change where organisms adapt to the world and take their place in the Chain of Being as either an eater or an eatee. Nothing dramatic, one generation looks much the same as the next. It takes many millions of years to grow a claw, or a penis, or a wing. Then in comes a big piece of space junk and overrides natural selection by wiping out a good chunk of lifeâ€™s rich diversity.
The Romans called it decimation â€” the random removal of ten percent of the population. They would march into a newly conquered town full of skulking goths or visigoths and kill one in ten just to maintain fear and public order.
Out there in space itâ€™s like a big old grinder. Asteroids and big chunks collide and make debris of smaller pieces. Collisions are rare because the space between space rocks is so large, but over billions of years large gets ground down into small. The result is a sparse interplanetary beach, with a few boulders, a bunch of pebbles, and countless grains of sand.
This stuff rains in on Earth at speeds of tens of thousands of miles per hour. Luckily the atmosphere burns up most of the small chunks. Yet every day, a trillion or so dust motes from space settle onto the Earthâ€™s surface, and about a million sand grains fall. How do we know? After all, dirt from space looks just like dirt. Scientists go down to the perfect blue-white ice pack of the Antarctic, and the space dust is just lying on the surface. Nothing else there, except the occasional penguin. So they push sticky rollers up and down the ice to trawl for the dust, like crazed Zamboni drivers on an ice rink.
Larger space junk is rare, but more worrying. Every week or so a car-sized chunk careens toward us. Most of these break up or detonate in the upper atmosphere, with the force of a Hiroshima blast. In the early 1960s, during the frosty depths of the Cold War, both sides noticed these atmospheric blasts. Each side assumed the other was welshing on arms agreements, and nervous fingers were poised over buttons. Scientists figured it out and the Dr. Strangeloves went back to their bunkers. But debris from space nearly pushed us over the nuclear brink.
About once per century a rock the size of a small apartment building slams into the Earth and makes a crater five football fields wide. The last time it happened was in Siberia in 1908. An area of forest the size of a big city was leveled and tremors were felt as far away as London. Siberia is big and empty so almost no one was killed. Some herdsmen were burned, one was thrown into a tree, and a few were thrown off their porches. Many more must have felt the blast and looked with new respect at their jug of potato vodka. With the last jolt nearly 100 years behind us, you can do the math. Weâ€™re due.
Then there are the big sonsofbitches. About every million years, a meteor the size of a small mountain hits Earth and flattens an area the size of Belgium or New Jersey. Such an impact would be seriously bad news (unless you have no sympathy for really bad drivers and really bad sports teams), releasing an explosive force equal to a billion tons on TNT, or the sum of all the worldâ€™s arsenals. Hundred-foot tidal waves would sweep across the oceans, throwing enough dust into the atmosphere to dim the Sun and cause massive crop failure and famine. And these are not the really big impacts.
Donâ€™t ask. You donâ€™t want to know. Oh, all right. Every hundred million years, give or take ten million, a monster the size of a city nails the planet. The oomph is ten million times that of Mount St. Helens blowing its top. Thereâ€™s nowhere to hide. Thousand-foot tidal waves circle the world over and over. Global forest fires rage. The sky darkens long enough to disrupt the food chain. Plankton die and grass withers. Extinction. Bummer.
Sixty five million years ago a monster rock slammed into the Gulf of Mexico. Its effect would even have penetrated the margarita daze of the partiers in nearby Cancun. For tens of millions of years, mammals had scurried around nervously in a reptileâ€™s world. Then the Big One falls and the dazed mammals are left to inherit the world and eventually spin off an unfinished experiment called humanity.
It makes you think about destiny. Somewhere out there is a silent assassin sailing through space with our number on it. The events that will bring it on a collision course with the Earth have not yet taken place. Maybe it is a comet. On one of its passages from the deep-freeze of the solar system it gets a nudge from Neptune then a tug from Jupiter and then itâ€™s trawling through the inner regions where the terrestrial planets dwell. Many orbits later, its trajectory will cross that of the innocent Earth. As an outfielder races across the grass toward the lazy arc of a fly ball, the two objects will meet in space and time.
Do you have an irrational fear of meteoric impacts? Letâ€™s look at that. The rarest condition is a level 1 phobia â€” the fear of mass extinction by a catastrophic collision. Its most acute sufferers glance nervously upward every few minutes. They make no long-term investments. They know that the impactor will travel much faster than sound, and they imagine it is streaking towards them. In their minds, they freeze the instant when it is poised just overhead; a mountain looming in the sky as they walk to the Quickie Mart.
Relax. Take a load off. At one event in tens of millions of years, the chance of the Big One in our lifetimes is tiny. The human race is much more likely to be taken out by its trashing of the environment than by a rock from the sky. Anyway, our weapons guys have got it covered. Out at Los Alamos and Livermore, they have thought about this a lot, since Ivan has been de-fanged and we have all these useless piles of plutonium glowing among the yucca and mesquite of the western deserts. Astronomers scan the skies to look for anything large headed in our general direction. We then use supercomputers to calculate the orbits. Only if a big object is truly headed our way do we send out the nukes to save the day. Itâ€™s got to be done delicately, with a bank off to the side like a good pool shot. Nailed head-on we face a hail of deadly bullets instead of a single cannonball.
Level 2 phobia is fear of medium-sized impacts. Every thousand years or so, a country or region of the world is thrown into turmoil when the sky is lit up by meteors and people die as a few big chunks get through the atmospheric shield. Is it a coincidence that a new major religion springs up about every thousand years?
If you suffer from this fear, the only therapy is to start your own cult. Find some chunk of eastern Oregon that isnâ€™t already taken by militias and declare yourself the Bhagwan of Tunguska. File for tax-exempt status and gather as many gullible minds as you can. (Plan on turning many people awayâ€¦) As for the form of your new religion, the constitution pretty much allows you to roll your own. A mixture of yoga, micro-brewing, and free sex is highly recommended.
The fear of a personal impact is a level 3 phobia. Every year, about 100,000 chunks of space rock that are small but big enough to kill you hit the Earthâ€™s surface. Most of them fall into the oceans and most of the rest must hit land that does not happen to have a person standing on it. But every now and then, someoneâ€™s in the wrong place at the wrong time. What are the odds?
In 1650, a monk in Milan was praying when he was killed by a meteorite. That God, heâ€™s such a kidder. This century, we know only of a dog killed in Nahkla, Egypt in 1911. (Dogs reading this are probably thinking, what does he mean â€œonly.â€) There have been close calls. An Alabama woman was asleep when a meteorite came through the roof and ricocheted off her hip, burning her badly. Mrs. Hodges survived to become the person with the best ever story to tell at a cocktail party. Two houses in the same small town of Wethersfield, Connecticut were hit within a span of eleven years. In 1992, Michelle Knappâ€™s 1980 Chevy Malibu was hit in the trunk by a 30-pound meteorite. The space rock fused with her car, so collectors offered $69,000 for the whole thing.
Maybe youâ€™re getting twitchy by now. But thatâ€™s not a long list given the huge number of people in the world. Your odds of dying from a meteorite impact are about the same as your odds of dying from botulism. You are 100 times more likely to die in an air crash and you are 10,000 times more likely to die in a car crash. We all gotta go sometime, and it might be better to be taken out this way. Itâ€™s quick, itâ€™s relatively painless, and you would get commemorated in the name of the bolide that hit you. Beats an old gravestone covered with moss and dog pee any day.
Letâ€™s face it, weâ€™re not very rational about risk. We lock our doors at night, then drive without a seat belt. We watch our cholesterol count, then have unprotected sex. So if you still have some residual phobia, here are practical tips to avoid being nailed by space junk:
1. Donâ€™t fly. The atmosphere is your friend, burning up most of the rocks that meet us from space. When you fly, you place yourself above most of that cushioning layer. Plus do you really think those guys up front ever concentrate on what theyâ€™re doing?
2. Sleep standing up. Surface area is the problem. The bigger the target, the bigger your chances to getting hit. So lose a few pounds by all means, but also reduce your impact area by favoring the vertical over the horizontal. Mrs. Hodges had no one to blame but herself. Try sleeping in your closet hanging in a sleeping bag.
3. Build a bunker. After midnight, the Earthâ€™s forward rotation combines with its motion through space to increase the chances of a meteorite making it to the ground. In the early morning hours, and during any meteor shower, you are far better off surrounded by cans of Spam and your favorite CDs in the bomb shelter.
Sweet dreams and donâ€™t look up!