The document discusses the asteroid Apophis 99942, which has a small chance of impacting Earth on April 13, 2036. Apophis 99942 was discovered in 2004 and is estimated to be approximately 390 meters wide. If it were to impact Earth, the explosion would be over 100,000 times more powerful than the Hiroshima atomic bomb. The document outlines several potential methods to deflect an asteroid on a collision course with Earth, including using kinetic impactors, ion thrusters, gravity tractors, nuclear explosions, solar sails, or swarms of mining robots.