Asteroid defense refers to the strategies and technologies developed to protect Earth from potential asteroid impacts. Scientists monitor near-Earth objects (NEOs) using telescopes and radar to identify those that could pose a threat. If a dangerous asteroid is detected, various methods, such as deflection or disruption, can be employed to alter its trajectory. One proposed method for asteroid deflection involves using a spacecraft to collide with the asteroid, changing its path through kinetic impact. Another approach is to use a gravitational tractor, where a spacecraft's gravity gradually pulls the asteroid off its collision course. Organizations like NASA and ESA are actively researching these techniques to ensure planetary safety.