OSIRIS-APEX is a mission to shadow Apophis, a giant asteroid, just after the rock barely avoids hitting Earth. If successful, OSIRIS-APEX will take modern humanity’s closest call with a major asteroid and turn it into an opportunity: a chance to better understand asteroids, learn more about how the Solar System formed, and help prevent future impacts.

On April 13, 2029, the asteroid Apophis — which is about as tall as the Empire State Building and three times as wide and long — will pass closer to Earth than the orbits of some satellites. If the asteroid hit Earth, the energy of the collision would be roughly equivalent to 1,000 of the most powerful nuclear bombs in the United States’ arsenal.

But Apophis won’t hit Earth. Instead, OSIRIS-APEX will watch from a distance as the asteroid flies by, then catch up to study it in more detail. The spacecraft will map Apophis, track its trajectory, and eventually fire thrusters to stir up its surface.

If this sounds familiar, that’s because OSIRIS-APEX is an extension of the OSIRIS-REx mission to study the asteroid Bennu and collect rocks from its surface. After the probe successfully sent samples back to Earth in 2023, it still had fuel left — so the mission charted a course for Apophis and was reborn under a new name.