Planetary Defense: How to Become Armed and Ready

NASA's Near Earth Object (NEO) observation program has been finding and tracking NEOs for about a quarter of a century uncovering about 40% of the 100,000 objects expected. Today it has been determined that a collision of a very large NEO with the Earth would be a rare but life altering occurrence. The near miss of comet Siding Spring to Mars moving at a phenomenal 56 km/s and at a size of half a kilometer should be humanities wakeup call. This comet came out of the Oort Cloud at an inclination of 129o to the ecliptic and was first spotted only 22 months before its near miss of Mars. It was a complete surprise to scientists worldwide. The close flyby of the comet caused Mars to be nearly engulfed by the comet’s coma and dust tail, leading to significant but short-lived changes in the Martian atmosphere. Had this comet hit the Earth, based on our current unprepared state, it would have been impossible to stop a significant extinction event. The recent detection of three interstellar comets presents another low probability but high impact danger. It is now clear that Earth impacts from Oort Cloud comets and interstellar objects are a type of “Black Swan” event which are extremely rare, unpredictable events that have massive, wide-ranging consequences. Planetary defense techniques have become more mature for Earth bound asteroids while cometary “Black Swan” threats have been largely ignored to date. This paper proposes to mitigate this problem by implementing a quick reaction kinetic impactor system using the Space Launch System (SLS) to provide the largest impactor mass with the greatest possible velocity in space ready to go. This requires the SLS launch of the large impactor mass to be placed into cislunar space such that the payload can quickly reach an incoming comet at any inclination by using the Earth or Moon as the appropriate gravity assist or to newly discovered incoming asteroids approaching from unfavorable orbital paths, such as directions close to the Sun.