An Analysis of the Correction Problem for the Near-Earth Asteroid (99942) Apophis=2004 MN4
A hazard mitigation problem for the Apophis-Earth collision (with an impact energy of about 103 megatons TNT) is analyzed in the paper. According to the asteroid observations performed and the asteroid orbit calculated on the base of these observations, the asteroid Apophis will fly in 2029 at ~ 40,000 km distance from the Earth without the collision. However, it is shown in the paper that some its trajectories, which are close to the nominal one, will hit on the Earth in 2036. The necessary correction of the asteroid velocity to deflect it from the Earth in 2036 is analyzed. The velocity impulse for the correction is evaluated depending on the correction scheme and the correction time. It is shown that it is desirable to perform the correction of the Apophis orbit before the asteroid-Earth collision in 2029. In this case, the necessary velocity impulse for the correction will be less considerably than for the correction after this collision. Possibilities to use thermo-nuclear effect and impact-kinetic one for this correction are estimated, too. It is noted that observations during the Apophis-Earth approaches in 2013 and 2021 will give good information to determine more precisely the Apophis orbit and its physical characteristics. This is important to design and perform the reliable correction.