Asteroid Apophis to skim by Earth in 2029 as NASA’s OSIRIS-APEX trails to study gravity’s effect
In April 2029, asteroid 99942 Apophis will pass about 32,000 km above Earth — closer than geostationary satellites — and NASA’s OSIRIS-APEX will watch from afar and then trail the asteroid to map how Earth’s gravity changes its orbit, rotation and surface. The mission will use cameras, spectrometers and a laser altimeter to characterize Apophis’s shape and composition, with a close ground-proximity pass later used to study surface changes, while Earth provides a well-understood gravitational test for a potentially hazardous, rubble-pile body.