NASA's OSIRIS-REx spacecraft, fresh from its groundbreaking mission to gather samples from an asteroid in deep space, has been assigned a new task: to study another asteroid during its close approach to Earth.
The spacecraft concluded its seven-year, 4 billion-mile round trip to collect samples from the asteroid Bennu in September. However, instead of decommissioning the spacecraft, the team proposed a second mission to the asteroid Apophis, which is anticipated to pass closer to Earth in 2029 than any other asteroid of comparable size in recorded history.
The spacecraft has been renamed OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification, and Security Apophis Explorer).
Dani Mendoza DellaGiustina, the principal investigator for OSIRIS-APEX, described the close approach as a "great natural experiment" in a NASA press release last week. "We know that tidal forces and the accumulation of rubble pile material are foundational processes that could play a role in planet formation. They could inform how we got from debris in the early solar system to full-blown planets."
Apophis, a space rock over 1,000 feet wide, was first discovered in 2004. Named after an Egyptian deity and nicknamed the "God of Chaos," the asteroid is expected to pass within 20,000 miles of Earth's surface closer than some satellites on April 13, 2029.
Asteroids of this size are estimated to pass Earth this closely only once every 7,500 years. Initially, scientists estimated a 3% chance of the asteroid colliding with Earth. However, over time, they concluded that there would be no collision in 2029, nor during Apophis' return trip in 2036.
The close encounter with Earth will alter the asteroid's orbit and the length of its day typically 30.6 hours. It could also trigger quakes and landslides on Apophis, potentially exposing material beneath the asteroid's surface.
Amy Simon, the missions project scientist, stated in the NASA press release, "OSIRIS-APEX will study Apophis immediately after such a pass, allowing us to see how its surface changes by interacting with Earths gravity."
Approximately two weeks before the asteroid passes Earth, OSIRIS-APEXs cameras will begin photographing it. The spacecraft will then arrive at Apophis on April 13, 2029, and remain with it for the next year and a half to study any changes caused by the close encounter.
Unlike its mission to Bennu, OSIRIS-APEX will not make contact with Apophis. Instead, the spacecraft will descend within 16 feet of the asteroid's surface and fire its thrusters to stir up rocks and dust, providing scientists with a glimpse of what lies beneath.
NASA is hopeful for unexpected discoveries. "We learned a lot at Bennu, but now were armed with even more questions for our next target," Simon said in the press release.
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