Astronomers employ various methods to detect and track incoming asteroids to determine if they pose a potential threat to Earth. Here are some of the key approaches:
Surveys: Dedicated sky surveys, such as the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and the Asteroid Terrestrial-Impact Last Alert System (ATLAS), scan the sky repeatedly, searching for moving objects. These surveys use wide-field telescopes and advanced imaging techniques to detect asteroids.
Optical Telescopes: Astronomers use ground-based telescopes to observe and track asteroids. By repeatedly observing their positions over time, astronomers can calculate their orbits and predict their future paths. This allows them to determine if an asteroid's orbit intersects with Earth's orbit.
Radar Observations: Radar is another powerful tool for studying asteroids. Radar systems bounce radio waves off the surfaces of asteroids, allowing scientists to measure their size, shape, rotation, and trajectory with great precision. Radar observations can be performed from Earth-based observatories or using spacecraft equipped with radar instruments, such as NASA's Goldstone Deep Space Communications Complex.
Space-based Telescopes: Space telescopes, such as the Near-Earth Object Surveillance Mission (NEOSM) and the future NEOCam (Near-Earth Object Camera), offer advantages in terms of reduced atmospheric interference and the ability to observe asteroids at different wavelengths. These space-based observatories can complement ground-based observations and provide additional data.
Once an asteroid is detected and its trajectory indicates a potential Earth impact, scientists and space agencies collaborate to evaluate the threat and consider possible mitigation strategies. Depending on the size and trajectory of the asteroid, options like gravitational tractor, kinetic impactor, or deflection missions could be planned to divert or mitigate the threat. However, it's important to note that no asteroid has been identified as an imminent threat to Earth.