Ummm.... I wonder if Nasa’s calculations include the impact of earth’s gravity on the asteroid’s path?
Go here:
http://ssd.jpl.nasa.gov/horizons.cgi#results
take the tutorial.
The object you want is:
Asteroid (2012 DA14)
Your location is 500 (Geocenter)
Time span is =2013-feb-15 19:00 UT, Stop=2013-feb-15 20:00
Table settings: Table Settings [change] : QUANTITIES=20,22
This is a three body problem (Earth, Moon, Asteroid) the math is pretty hairy on a 3 body problem, but it is solvable. So if NASA and the rest of the scientific community say near miss then it is a near miss, THIS TIME. However the asteroids’ orbit will be effected by passing so close to the earth, so who knows maybe next time?