Asteroid Deflection Aftermath - Apophis revisited
Lu, Edward; Lu, E.T.
B612 Foundation

The successful deflection of a threatening asteroid turns an impact trajectory into a near miss trajectory with a resulting close fly-by of Earth. This new trajectory therefore must be ensured to be clear of return impact keyholes at the time of the close approach. Thus the situation we are presented with Apophis, of a close approach followed by a potential impact in case of keyhole passage is therefore not a rare case, but rather a case that must be confronted with every deflection scenario. The response to an impact threat must be thought of as a deflection campaign, with several stages including initial asteroid orbit determination/confirmation, primary deflection, reassessment of the new asteroid orbit, and possible fine tuning to prevent keyhole passage. The results of the B612 Foundation - JPL Gravitational Tractor study will be used to illustrate this concept.