Hyper-velocity Asteroid Mitigation Mission for Emergency Response (HAMMER) is a concept study by NASA on a spacecraft (8 tonnes) capable of detonating a nuclear bomb to deflect an asteroid, if it was on a collision course to Earth. The study is a collaboration between the National Nuclear Security Administration, NASA, and two Energy Department weapons labs.[1][2][3]
Bennu
NASA is working on a modelling study that considers the asteroid 101955 Bennu, which has a diameter of 246 meters and capable of a 1.15 gigaton impact, as a modelling target for the HAMMER concept.[4][5] It is circling the Sun at 63,000 mph and 54 million miles from the Earth.[6]
The two realistic responses considered in the study are the use of a spacecraft functioning as either a kinetic impactor or a nuclear explosive carrier to deflect the approaching asteroid.[7]