Apophis Exploration
Quick Facts
Apophis was discovered on June 19, 2004, by astronomers Roy Tucker, David Tholen, and Fabrizio Bernardi
The asteroid is named for Apophis, the ancient god of evil and destruction.
Apophis is little longer than an NFL football field, and it's about the height of the Eiffel Tower.
Apophis is an S-type, or stony-type asteroid.
Apophis was discovered on June 19, 2004, by astronomers Roy Tucker, David Tholen, and Fabrizio Bernardi at Kitt Peak National Observatory in Tucson, Arizona. They were only able to observe the asteroid for two days because of technical and weather problems. Fortunately, a team at the Siding Spring Observatory in Australia spotted the asteroid again later in the same year.
NASA has redirected a spacecraft to study Apophis. After successfully completing its mission to gather a sample of asteroid Bennu and deliver it to Earth in September 2023, OSIRIS-REx was sent to study Apophis. Now renamed OSIRIS – APophis EXplorer (OSIRIS-APEX), it will rendezvous with Apophis shortly after the asteroid's 2029 Earth close-approach.
OSIRIS-APEX will pass by Earth just an hour behind Apophis, using Earth’s gravity to put it on a parallel course to Apophis. It will then arrive at Apophis in June for an 18-month campaign to map the asteroid’s surface and analyze its chemical makeup. OSIRIS-APEX’s cameras will begin taking images of the asteroid as the spacecraft catches up to it, just before the asteroid’s close-approach with Earth.
The European Space Agency, ESA, also is sending a spacecraft to study Apophis. The Rapid Apophis Mission for Space Safety (Ramses), will rendezvous with the asteroid and accompany it through its close flyby of Earth in 2029. The current plan is for Ramses to launch in April 2028 and arrive at Apophis in February 2029, two months before the close approach.
Apophis will also be closely observed by Earth-based telescopes during this time. Observatories around the world and in space will observe asteroid Apophis’ historic close approach to better understand its physical properties. NASA also organizes the International Asteroid Warning Network (IAWN), which will coordinate Earth-based telescopic observing campaigns before and around the time of the asteroid’s flyby with our planet.
But in the hours after the close encounter, Apophis will appear too near the Sun in the sky to be observed by ground-based optical telescopes. This means any changes triggered by the close encounter with Earth will be best detected by the spacecraft.
In addition to studying changes to Apophis caused by its Earth encounter, the spacecraft will conduct many of the same investigations OSIRIS-REx did at Bennu, including using its instrument suite of imagers, spectrometers, and a laser altimeter to closely map the surface and analyze its chemical makeup. The spacecraft will maneuver around Apophis, taking images and spectra from a wide variety of viewing angles. It will then orbit Apophis from about half a mile (1 kilometer) away, so that OLA, its Canadian-built laser altimeter, can completely measure Apophis’ shape. It will use more maneuvers and orbits to map the surface as completely as possible with all its instruments.
As an encore, OSIRIS-APEX may reprise one of OSIRIS-REx’s most impressive acts, dipping within 15 feet of the asteroid’s surface and firing its thrusters downward. This maneuver will stir up surface rocks and dust to give scientists a peek at the material that lies below. Unlike Bennu, the spacecraft will not collect a sample from Apophis.
