Apophis would pass through a "gravitational keyhole", a specific region in space no more than about 400 meters across that would set up a future impact on 13 April 2036.
Planetary Society is offering a $50,000 prize for the best plan to put a tracking device on or near the asteroid. It is predicted that the comet will change its orbit and might attack us again in 2036. The University of Hawaii's Pan-STARRS program is training four powerful digital cameras towards the heavens to watch for the attack. Impact Summary
Its a 5x1010kg asteroid and has a temperature of -290K. Additional observations through 2006 resulted in Apophis being lowered to Torino Scale 0 on August 6, 2006. NASA astronaut Edward Lu is campaigning for a new space tractor, costing between $200 million and $300 million that would divert this asteroid on a path to slam into Earth by changing the space rock's orbit."We're only trying to get a really tiny change in the velocity of the asteroid to prevent an impact," said Lu, a former University of Hawaii solar physicist.