NASA’s OSIRIS-REx mission, now OSIRIS-APEX, is gearing up to study Apophis, a space rock named after the Egyptian god of chaos and darkness, as it comes within 20,000 miles of Earth in approximately 5 ½ years. OSIRIS-APEX, short for Origins, Spectral Interpretation, Resource Identification, and Security-APophis Explorer, will closely orbit Apophis for 18 months after its April 13, 2029, close approach, using Earth’s gravity to do so. This mission is vital for scientific exploration and Earth’s defense against potential asteroid threats. It follows OSIRIS-REx’s successful delivery of NASA’s first asteroid sample, although it won’t collect samples from Apophis; instead, it will use gas thrusters to stir up dust and rocks for study. Understanding Apophis, an S-type asteroid, compared to C-type Bennu, offers insights into stony asteroid composition and potential impacts on Earth, while aiding in planetary defense strategies.

“Apophis is one of the most infamous asteroids,” says Dani DellaGiustina, principal investigator of OSIRIS-APEX. Despite initial concerns about an impact in 2029, subsequent observations ruled out this risk. However, Apophis will make the closest approach of an asteroid of its size in recent history, passing within one-tenth the distance between Earth and the moon. This presents a unique opportunity for scientific observation, and people in Europe and Africa will be able to see it with the naked eye during the 2029 encounter. Continuous monitoring of Apophis will provide crucial data on its orbit, surface, and rotation rate, ensuring Earth’s safety from potential future impacts.