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The former OSIRIS-REx spacecraft sets off on a journey to study asteroid Apophis and take advantage of the asteroid\u2019s 2029 flyby of Earth, the likes of which hasn\u2019t happened since the dawn of recorded history.<\/p>\n<\/div>\n
At the end of a long-haul road trip, it might be time to kick up your feet and rest awhile \u2013 especially if it was a seven-year, 4 billion-mile journey to bring Earth a sample of asteroid Bennu. But OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security \u2013 Regolith Explorer), the NASA mission that accomplished this feat in September, is already well on its way (with a new name) to explore a new destination.<\/p>\n
When OSIRIS-REx left Bennu in May 2021 with a sample aboard, its instruments were in great condition, and it still had a quarter of its fuel left. So instead of shutting down the spacecraft after it delivered the sample, the team proposed to dispatch it on a bonus mission to asteroid Apophis, with an expected arrival in April 2029. NASA agreed, and OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification, and Security \u2013 Apophis Explorer) was born.<\/p>\n
After considering several destinations (including Venus and various comets), NASA chose to send the spacecraft to Apophis, an \u201cS-type\u201d asteroid made of silicate materials and nickel-iron \u2013 a fair bit different than the carbon-rich, \u201cC-type\u201d Bennu.<\/p>\n
The intrigue of Apophis is its exceptionally close approach of our planet on April 13, 2029. Although Apophis will not hit Earth during this encounter or in the foreseeable future, the pass in 2029 will bring the asteroid within 20,000 miles (32,000 kilometers) of the surface \u2013 closer than some satellites, and close enough that it could be visible to the naked eye in the Eastern Hemisphere.<\/p>\n
Scientists estimate that asteroids of Apophis\u2019 size, about 367 yards across (about 340 meters), come this close to Earth only once every 7,500 years.<\/p>\n
\u201cOSIRIS-APEX will study Apophis immediately after such a pass, allowing us to see how its surface changes by interacting with Earth\u2019s gravity,\u201d said Amy Simon, the mission\u2019s project scientist based at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.<\/p>\n
Apophis\u2019 close encounter with Earth will change the asteroid\u2019s orbit and the length of its 30.6-hour day. The encounter also may cause quakes and landslides on the asteroid\u2019s surface that could churn up material and uncover what lies beneath.<\/p>\n
\u201cThe close approach is a great natural experiment,\u201d said Dani Mendoza DellaGiustina, principal investigator for OSIRIS-APEX at the University of Arizona in Tucson. \u201cWe 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.\u201d<\/p>\n
Apophis represents more than just the opportunity to learn more about how solar systems and planets form: As it happens, most of the known potentially hazardous asteroids (those whose orbits come within 4.6 million miles of Earth) are also S-types. What the team learns about Apophis can inform planetary defense research, a top priority for NASA.<\/p>\n
By April 2, 2029 \u2013 around two weeks before Apophis\u2019 close encounter with Earth \u2013 \u00a0OSIRIS-APEX\u2019s cameras will begin taking images of the asteroid as the spacecraft catches up to it. Apophis will also be closely observed by Earth-based telescopes during this time. 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 will be best detected by the spacecraft.<\/p>\n \n