Planetary Defenders: This Is Not an Exercise

When a newly discovered asteroid posed a potential risk to Earth, a global planetary defense system was put to the test like never before.

Planetary Defenders: This Is Not an Exercise tells the story of how NASA, its international partners, the astronomy community, and scientists around the world raced to observe and track the asteroid, understand its orbit into the future, calculate its impact probabilities, and eventually retire it from the risk list.

Learn more about NASA’s efforts to find, track and monitor near-Earth asteroids: https://science.nasa.gov/planetary-defense/
Download this episode: https://images.nasa.gov/details/NHQ_2026_0928_Planetary%20Defenders%20This%20Is%20Not%20an%20Exercise
Watch the debut episode of "Planetary Defenders": https://www.youtube.com/watch?v=jOb2DQWvDvc