What is one and one half football fields in diameter and is hurtling in from the outer void to smash the world to bits on the 15th of February, 2013? Nothing that is currently known about, but on that particular day asteroid 2012 DA14 is going to come just about as close as an extra planetary body can and still miss.
DA14 is a newly discovered arrival in the catalog of asteroids; it was only discovered on the 22nd of February 2012 less than two months ago at the time of this writing. When spotted, it had already passed close by the Earth in astronomical terms, whizzing by just a mere 1.5 million miles away. The astronomical team at the La Sagra Sky Survey located just outside of Grenada, Spain, was able to pick the intruder up as it was fading in the distance.
This was an admirable accomplishment because given the relatively small size of the asteroid, its velocity and low luminosity, it was a difficult object to target and track. The information that astronomers and mathematicians were able to extract from the partial orbital information reveal some interesting details.
For one, the orbit of DA14 is very much like that of the Earth at roughly the same distance from the sun, with a similar elliptical shape, and even a very similar period. DA14 orbits the Sun in 366.24 days taking just a day longer than Earth to make the trip.
The difference is that DA14’s orbit is tilted relative to that of the earth's, appearing above and then below the plane of that orbit. This means that twice each year, DA14 will cross Earth’s orbit, with greater or less proximity depending where in their interactive cycle the two celestial bodies are.
How close is close in 2013? Try a mere 17,000 miles as a best guess. That will bring DA14 14 times closer to the Earth than is the orbit of the moon and closer in fact than many of our artificial satellites. It is a very close shave, but NASA scientists and others are adamant, Earth will not be struck.
That’s definitive and reassuring, but then researchers at the Near Earth Program out of Pasadena California’s Jet Propulsion Laboratory seem to hedge their bets, stating that DA14 cannot possibly come closer than 12, 680 miles. Consensus at the greater distance would be highly desirable but the scientific community needs to refine their figures before consensus of any variety can be expected.
What if the asteroid should score a direct hit on Earth? Fortunately, it is not large enough to have a global impact; there will be no earthquakes or volcanic eruptions, no major tsunami. However, an object of that mass moving at that velocity does pack the wallop of a major nuclear bomb and should it strike a populated area the results would be tragic indeed. The impact has been compared to that of the object that exploded over Tunguska, Siberia in 1908, leveling 80 square miles of mostly uninhabited forest.
Had that same event occurred over Berlin, or Moscow, or London, the course of world history would have taken a very different path.
The real cautionary tale lies not so much in what DA14 may or may not do, it has made the voyage in and out of earths orbit millions of times with no negative results thus far. The greater concern is the estimated million or more near Earth space travelers which have not yet been located or tracked and which could arrive upon the scene at any moment, with possible cataclysmic result.