TC4: How NASA Plans to Test its Planetary Defense Systems on Close-Approach Asteroid

NASA and FEMA Conduct Asteroid Impact Emergency Planning Exercise
(Image by NASA)   Details   DMCA

Paul Chodas from NASA’s CNEOS says the exercise will be the same as if the asteroid were on course to hit Earth.

A network of astronomers will be tracking TC4. You want to know early on the composition and the size. We have a rough idea of its size from its brightness in optical wavelengths but we have to make an assumption on its reflectivity. Dark asteroids are known to have low densities, and bright asteroids are known to have rockier, higher densities.