The asteroid has a poorly constrained orbit and often makes close approaches to Earth, and should make one such approach sometime between March 6–10, 2016.[2] While the nominal (best-fit) orbit suggests that it will pass 0.03 AU (4,500,000 km; 2,800,000 mi) from the Earth on March 8, it may pass as close as 0.0002 AU (30,000 km; 19,000 mi) (0.07 LD).[2] It may also pass as far away as 0.1 AU (15,000,000 km; 9,300,000 mi).[2] There is no risk of an Earth impact in 2016.[3] The asteroid is 21–52 meters (69–171 ft) across, making it approximately twice as large as the Chelyabinsk meteor.
“No chance”?
That’s not how probabilities work. The likely distance from Earth at the object’s closest approach can be plotted as a bell curve. The asteroid’s “best fit” orbit projects passage at 2.8 million miles away. It is said it “may” get as close as 19,000 miles, or, putting it another way, it may stray as close as 2.781 million miles away from the “best fit”, toward the Earth. If there is a 0.01% chance that the asteroid will come as close as 2.781 million miles from “best fit”, then the odds it will stray as close as 2.8 million miles from “best fit” are only slightly lower.
BTW, is the text you cite old data? A range of 21-52 meters diameter is fairly significant: We are looking at (assuming the thing does at least collide destructively with Earth’s atmosphere), on the low end, a Chelyabinsk type event, and on the high end, almost 18 times as much energy released as the Chelyabinsk event. (This assumes incoming velocity is the same — if this baby is coming in significantly faster, that increases the energy yield too. (The Chelyabinsk meteor, B4 it hit the atmosphere, is calculated to have been traveling at ~ 19 km/s, just over “average.)
Another way to look at it is that the Barringer crater meteorite is estimated to have been 50m diameter, with an impact speed of 12.8 km/s. Chelyabinsk is estimated at 500 kilotons, Barringer is estimated at 10 megatons, or a 20x bigger bang: not too far off my 18x calculation above.
The atmosphere slows down “little ones” more, assuming equal angles of entry, but, then, Chelyabinsk did not make it through the atmosphere, luckily for the locals! If it had come in near vertical at a city...
At any rate, should our new friend defy the odds and land on, say, me, the “bang” is going to be serious.