If Hollywood hasn't hammered this into you enough by now, here's one more reminder: A giant asteroid slamming into Earth is a bad thing. After all, how many dinosaurs have you heard reminiscing about the K-T boundary extinction event? The catalyst for the mass extinction of the human race could be hurtling toward Earth right now. In fact, many scientists would guarantee it. Fortunately, we already have at least 10 rough game plans on how to deal with the threat of near earth asteroids (NEAs). Sorry, movie fans, but none of them involve Bruce Willis.
Makes sense, doesn't it? If the universe is going to play hardball, then we should pull out our big guns as well: nuclear weapons.
The idea of sending a nuclear gift basket isn't to destroy the incoming asteroid, but rather to deflect it. Otherwise a wayward space rock could be transformed into cosmic buckshot, with all that deadly debris still headed on a crash course with our tiny little world.
Perhaps surprisingly, a blast's intense radiation -- not unadulterated force -- might get the job done. Such energy would vaporize a section of the asteroid's surface, causing it to eject surface material into space like countless tiny rockets.
Some scientists think the whole "nuke the asteroid" strategy is overreacting. Why not give it a kinetic love tap?
Enter NASA's alternative "kinetic interceptor," which would deflect an incoming asteroid by smacking into it. Like shooting a rolling bowling ball with a pellet gun, the idea is to just barely nudge the asteroid off course -- but not hard enough to fracture it. According to Space.com, a mere 1 mile-per-hour (1.6 kilometer-per-hour) impact would be enough to divert an asteroid by 170,000 miles (273,500 kilometers) if we hit it 20 years before the predicted collision.
Painting an asteroid may sound ludicrous: When impending doom is headed straight for Earth, is it really the time to think about redecorating? If you factor in something called "solar powered orbital mechanics," it's a great time.
On a hot and sunny day, would you wear a white shirt or a black shirt? Black might be the new black again by the time you read this, but the smart choice is white; it reflects more solar radiation (while dark colors absorb it). Similarly, paint part of an asteroid white and the colored section will feel more "push" from solar radiation, providing a slight nudge to push it gradually off of a course to kiss Earth goodbye. The "paint" in question could also take the form of light-colored dust or chalk -- anything to change the ratio between absorbed and reflected radiation.
Paint may not appeal to everyone, but using the sun's powerful wind of energy against an incoming asteroid plays a crucial role in several deflection strategies.
Take, for instance, sending a spacecraft to attach a giant solar sail to the surface of a near-Earth asteroid. This structure, once unfurled, would reflect solar radiation and gently push an asteroid away from its original destination. In some plans, the sail would even be adjustable to provide a certain degree of remote control. Many experts doubt about attaching anything to an asteroid, however, is a wise idea. After all, these rocks are tumbling and spinning and, while we've landed unmanned vessels on asteroids before, we've hardly set up anything as complex as a working solar sail there.
Netting a rogue asteroid may sound too much like a Wile E. Coyote ploy, but NASA has given the prospect some serious thought (and with nary an ACME Corporation mail-order catalog in sight).
Scientists within the space agency think a carbon-fiber mesh weighing somewhere in the neighborhood of 550 pounds (249 kilograms) could be enough to change the potentially incoming asteroid Apophis' course. The idea? The net material would act like a solar sail, increasing the amount of solar radiation absorbed and emitted by the asteroid. Apophis isn't slated to come dangerously close to Earth until 2029, and then again in 2036 if it's just teasing us the first time. Scientists predict a mere 18 years of entanglement in the net could cast such a doomsday object clear of our world for the foreseeable future.
Mirrors work on vampires and gorgons, so why not monstrous asteroids? Brandishing a mirror against an asteroid actually has much more in common with the nuclear option mentioned before. Strategically positioned mirrors could concentrate solar rays, heat a small portion of an asteroid's surface, and cause it to spew vapors. As this material ejects from the asteroid, it would provide a little thrust to alter the space rock's path. Early ideas called for a colossal single space mirror, but modern revisions lean toward a multiple-mirror system to work in unison. Among scientists, the mirror strategy is referred to as laser sublimation.
Enough with the "easy does it" methods to divert an asteroid. Why not just strap a big, honking rocket to one and light the fuse? At times, it pays to be more direct -- and some scientists agree. They propose landing a vessel on the surface of the asteroid, digging in and firing up some roof-mounted chemical rockets to push any naughty near-Earth objects steadily away from a cataclysmic rendezvous with our blue marble.
To many people, "gravitational tractor" may sound like some made-up technology in an episode of Star Trek, but the premise is fairly simple. Every object in the universe exerts a gravitational pull, including asteroids and man-made spacecraft. Gravity may be one of the weakest forces in the universe, but is also the most "ready-to-use" since all you need is a little mass -- so it makes sense to unleash it against asteroids. Theoretically, all we'd have to do is navigate a hefty robot close to the asteroid and tow it away with the gentle pull gravity.
Not everybody's onboard with this method, however. To keep a spacecraft from crashing into the surface of the asteroid, thruster may need to be aimed in the asteroid's direction. This could push against the asteroid enough to counter any towing action. Plus, the cost may be astronomical compared to other methods... How much was that painting idea again?
Rocketing packs of ravenous robots out to an asteroid to eat it sounds like the musing of a madman (or a 1980s arcade video game creator), then your hunch was right; the NASA-funded Modular Asteroid Deflection Mission Ejector Node -- aka MADMEN -- project involves just this.
The idea is to send nuclear-powered robots to a threatening asteroid, where they'd land and begin mining or "chewing" into the surface of the rock. They would then eject these fragments into space at high speed via electromagnets.
Ideally, this would provide the same sort of thrust that mounted rockets would deliver -- only without the need for any chemical fuels. As you might imagine, however, it will take serious research and development to see this plan through to fruition.
Hey, we deemed this list "ways to stop an asteroid" -- we didn't say it couldn't be Earth!
If none of the nine aforementioned asteroid deflection methods pan out, there may not be much else to do if a near-Earth asteroid's course can't be altered with decades or even centuries of advance warning. So we may need to fall back on panicking.
You know... chaotic exoduses from major population centers, food hoarding and manic attempts to break through the gates into underground government bunkers. Plan to spend any time of the roads? Brush up on "The Road Warrior," and if you plan on surviving make sure a few viewings of "Mad Max" are under your belt.
If the future's really bleak, leave a friendly note for the cockroaches -- or whatever you think the forces of nature will pick as the next dominant species on Earth.