NASA Responds

[srij]

We are very fortunate that there are people out there whose job is to look for these things and warn us about them.

This sort of impact has happened before. It is widely believed that such an impact by an asteroid is responsible for changing the Earth in such a way as to adversely affect the dinosaurs, wiping them out. Also, The Tunguska Event is believed to be an explosion of a meteorite in the air above Siberia.

NASA provided a formal response to the B612 Foundation's June communique via an October 12 letter from Mary Cleave, Associate Administrator for Science Mission Directorate.
That NASA reply came with an appended detailed analysis by Steven Chesley of NASA'S NEO Program Office at the Jet Propulsion Laboratory (JPL) in Pasadena, California. The study by Chesley dug into Apophis' orbit, under varying conditions, and contained other items pertaining to the space agency's findings about the Apophis matter.
"The key conclusion to be taken from this analysis," Cleave explained in the letter, "is that aggressive (i.e., more expensive) action can reasonably be delayed until after the 2013 observing opportunity. For Apophis, the 16 years available after 2013 are sufficient to recognize and respond to any hazard that still exists after that time."
Cleave noted in the letter that while Apophis "is an object whose motion we will continue to monitor closely in the coming years, we conclude a space mission to this object based solely on any perceived collision hazard is not warranted at this time."
Not ruled out by Cleave, however, is the prospect of Discovery-class, low-cost missions sent to Apophis, "based on purely scientific arguments," she said.
"Indeed, the asteroid's orbit is particularly attractive for spacecraft rendezvous, and the extraordinary close encounter in April 2029 provides a unique opportunity to investigate a number of scientific NEO issues," Cleave explained in the letter.