It's big. Rose Bowl-sized big.
It's bad. 510 megatons of TNT bad.
What would that type of firepower equate to? Well, the largest atomic weapon ever detonated was the Tsar Bomba, a Soviet hydrogen bomb yielding roughly 50 megatons of destructive force. Simultaneously discharge ten of those babies, and you'd have a pretty good idea.
"Fat Man," the nuclear device dropped on Nagasaki, Japan, in 1945, was equivalent to 21 kilotons, nowhere near a single megaton of dynamite. Keep in mind, one thousand kilotons equal a megaton. Most estimates assert roughly 39,000 folks perished immediately from this blast.
Now, consider a force tens of thousands of times greater. We're no mathematicians, but it sounds like something of that magnitude could result in hundreds of millions of human deaths.
So, what exactly are we referring to?
Known as 99942 Apophis, it's a near-Earth asteroid headed toward the celestial body we call home.
In this particular case, the term near-Earth does not denote an object, as of yet, adjacent this planet. Instead, in the year 2029, Apophis is calculated to pass closer to us than communications satellites in geosynchronous orbit.
The bad news comes from what's known as the "keyhole," a theoretical window through which this asteroid may traverse as it glides by Earth. Should Apophis thread this region, which is about 2,000-feet wide, it will return again in the year 2036, striking the planet with 510 megatons of awesome force.
Astronomers have calculated that if Apophis impacts Earth, it'll do so in the Pacific Ocean, somewhere between Hawaii and San Francisco. Where this chunk of space debris traverses the keyhole becomes an important factor. A little to either side of this hypothetical portal, and the asteroid could hit further inland, or further out to sea.
The problem is there isn't only one keyhole. In fact, there are thousands. This means, even if Apophis fails to pass through the 2,000-foot wide ingress scientists have calculated, it's gonna thread some keyhole. Thus, the asteroid will return, at a date beyond 2036, to hit the planet.
"So, what's gonna happen if it does?" you tensely inquire.
Picture a tsunami so immense it obliterates not only the entire West Coast of North America, but Hawaii, Japan, and all the nations of the Pacific Rim. A tidal wave that makes the Indonesian Tsunami of 2004 seem like a lap pool.
"How come we haven't heard about this?!" you query.
Actually you have. Chances are, like most folks, you've engaged in other, more pressing activities; i.e. perusing Facebook, obsessing over who the next American Idol might be, or determining whether or not Kirstie Alley is fat this week. Apophis has been in the news, and you've had ample opportunity to read about it. You just haven't.
Yes, you may find this article depressing, but it doesn't have to be. Humans possess the level of intellect that could render Apophis a pleasant sighting in the nighttime sky, as opposed to a catastrophic asteroid.
Even though all technologically advanced countries on this planet are aware of Apophis, not much is being done to mitigate the problem it poses. You'd think something of this nature would be top priority. Unfortunately, it seems most governments have their hands full starting wars. We have a space program, and although we've allegedly been to the Moon, we haven't returned in 38 years. It's the same scenario. We can do something, but instead, we don't.
On the bright side, scientists have proposed methods for averting Apophis. Such scenarios include a gravity tractor, a spacecraft launched to divert the asteroid's path, without touching the celestial body. The gravitational field of this discharged probe, once adjacent Apophis, would, in theory, drag the space debris from a collision course with Earth.
A second method of mitigation is known as kinetic impact, actually striking the asteroid with an object. A sizable spacecraft, traveling at high velocity, may knock Apophis off its current course.
Don Quijote, a mission undertaken by the European Space Agency, is the first kinetic impact deflection strategy with the potential of being tested. Unfortunately, "Donny Boy" is currently in its blueprint stage. This being said, there's no way of knowing whether or not DQ could prevent an asteroid from colliding with Earth.
Focused solar energy is another option. Such a technique merely involves construction of a massive space station, comprised of gigantic lenses and an immense magnifying glass, directed toward the Sun. Why don't we just build a second Moon, and place it in orbit, while we're at it? In theory, these reflective devices would capture solar energy, and aim it toward the asteroid. Over an extended period of time, this conductivity may alter Apophis' path.
A fourth alternative involves attaching a "plasma engine, powered by a nuclear reactor" to the hunk of space junk, firing it, and thereby, pushing the celestial body off course.
The problem here is that Apophis is pretty big, and traveling at a high velocity. We'd need some serious firepower, over an extended period of time, to create a significant change in its trajectory. As long as the reactor remained operational, though, it may be a good option.
Unfortunately, Apophis, like all asteroids, is spinning. As a result, scientists would have to devise some sort of method for firing the plasma engine at constantly changing intervals, so that the celestial body doesn't veer back into harm's way.
"Couldn't we just blow the hell out of Apophis? We've got more nukes than we need. Why not send a couple skyward, and annihilate this pesky hunk of cosmic clutter?"
This one's probably the worst defensive strategy we could engage in. Nuking an asteroid may reduce it to fragments, but then you've got thousands of smaller asteroids headed toward Earth. Plus, resultant of the Partial Test Ban Treaty, it's been illegal to detonate atomic weapons in space since 1963.
Additionally, Apophis' composition may absorb nuclear devices launched its way. It's been proven numerous asteroids are as dense as Styrofoam. Should Apophis be one of these objects, it would simply suck up as many missiles as we could pump into it.
Currently, these proposals are no more than theories. We don't know if any would work. Ideally, scientists would love to have a hundred year advanced notice of potential impactors. Since these mitigation plans concern altering an asteroid's path over an extended period of time, the longer one has to do so, the better. If a celestial body was a hundred years from Earth, we'd need to deflect it far less than than an object a year from impact.
Most astronomers assert detection of space debris, ten years prior to collision, is sufficient time to avert disaster. Well, 2029 isn't that far off, and we don't have a defensive strategy anywhere near in place.
If you're wondering about the odds of you being killed by an asteroid, they're approximately the same as dying in a plane crash, one in nearly 700,000. Roughly a couple dozen folks have been wasted by stellar scraps over the last four hundred years. This number is deceiving, as Earth tends to be hit by something sizable on an average of every two centuries.
In 1908, three hundred square miles of Tunguska, Siberia, were wiped clean by either an asteroid or comet that exploded above the middle of nowhere. Had this object discharged over New York City, we would've been lookin' at millions of deaths. After all, this event yielded a devastating blast somewhere between five and 30 megatons.
To paraphrase astrophysicist Neil deGrasse Tyson, let's not be the dumb-asses of the Universe. We possess advanced intellect. Dinosaurs had brains the size of pebbles, and they were wiped out by a cosmic impact. Should we suffer the same fate, in the midst of our heightened intelligence, we'd only have ourselves to blame.
© 2011. Hugh Mungus
Plait, Philip, Ph.D. (2008). Death From the Skies: These Are the Ways the World Will End. pp. 1-32, 300-301. Penguin Books Ltd. ISBN 978-0-670-01997-7
Tyson, Neil deGrasse. (2007). Death by Black Hole: And Other Cosmic Quandaries. pp. 254-262. W.W. Norton & Company, Inc. ISBN-13: 978-0-393-06224-3