NASA has embarked on an ambitious new mission to study the near-Earth asteroid Apophis up close, an asteroid known as the ‘God of Chaos’ that will make an extremely close approach to Earth in 2029. The mission repurposes the OSIRIS-REx spacecraft, which recently returned samples from asteroid Bennu, equipping it with new instruments to investigate Apophis during the 2029 flyby.
OSIRIS-REx Reborn as OSIRIS-APEX
After successfully completing its primary mission of collecting samples from the asteroid Bennu and delivering them safely to Earth earlier this month, NASA has now tasked the OSIRIS-REx spacecraft with a new adventure – visiting the asteroid Apophis during its close Earth approach in 2029.
The mission has been dubbed OSIRIS-APEX, with APEX standing for Apophis Explorer. By intercepting Apophis in 2029, OSIRIS-APEX will be able to study changes in the asteroid over time and analyze its surface up close during the critical flyby that brings it within just 19,000 miles of Earth’s surface.
“OSIRIS-REx was a phenomenal mission and now we have a chance to utilize the hardware that we invested in to study Apophis,” said Lori Glaze, director of NASA’s Planetary Science Division. “It will allow us to observe how an object like Apophis evolves over time.”
The table below outlines the instruments onboard OSIRIS-APEX and what they will measure:
| Instrument | Measurement Capabilities |
|---|---|
| Camera Suite (OCAMS) | High-resolution color images of the asteroid’s surface features |
| Visible and Infrared Spectrometer (OVIRS) | Mineral and organic composition of Apophis |
| Thermal Emission Spectrometer (OTES) | Mineral and temperature maps of the surface |
| Laser Altimeter (OLA) | Precise shape model and gravity field |
| X-ray Spectrometer (REXIS) | Elemental composition of the surface |
Why Study Asteroid Apophis?
Discovered in 2004, asteroid Apophis quickly gained notoriety after initial observations indicated it had a 2.7% chance of striking Earth during its 2029 close approach. Further tracking has since ruled out an impact, but the 2029 flyby will bring Apophis within 19,000 miles of Earth’s surface – closer than some satellites in geosynchronous orbit.
Due to its size, a 340-meter-wide asteroid like Apophis colliding with Earth would cause widespread devastation across an entire region. By studying Apophis up close, scientists hope to better understand what factors make some near-Earth asteroids more likely to remain threats.
“Apophis is one of the most potentially hazardous asteroids that we know of,” said Marina Brozović, a scientist at NASA’s Jet Propulsion Laboratory working on the mission. “By observing Apophis during its 2029 flyby, we’ll gain important scientific knowledge that could one day be used for planetary defense.”
Preparing for Intercept in 2029
Over the next five years before reaching Apophis in 2029, the OSIRIS-APEX spacecraft will conduct several deep space maneuvers to precisely align itself with Apophis’ path.
In late 2026, OSIRIS-APEX will fly by Earth for a gravity assist maneuver that sets it on course for the 2029 asteroid rendezvous. NASA chose this extended flight plan rather than launching a dedicated mission in 2024 both for cost savings and to allow ample time for spacecraft checkouts before the Earth gravity assist.
Throughout the journey, the mission team will conduct instrument calibration activities and test out various operation scenarios using Apophis orbital models. This will ensure everything is prepared to collect maximum science when OSIRIS-APEX soars past the asteroid at over 24,000 mph in 2029.
Key Science Goals During 2029 Earth Flyby
The 2029 flyby offers a rare opportunity to study Apophis from multiple vantage points. As Apophis approaches Earth, OSIRIS-APEX will collect data on changes in the asteroid’s spin state, surface morphology, and composition – measurements that ground-based telescopes can simultaneously make from Earth.
Comparing the spacecraft data to ground observations will allow scientists to link remote properties like color and lightcurves to surface characteristics like boulders, craters, and loose dusty regions up close. These linked measurements can then be applied to other near-Earth asteroids only observed from afar to better interpret their hazardous potential.
In addition to surface change detection across epochs, another priority science goal is measuring the Yarkovsky effect on Apophis. This thermal force subtly alters the course of asteroids over time and plays a major role in impact hazard assessments. By precisely tracking Apophis position over 5 years, OSIRIS-APEX will quantify the strength of this effect.
Mission Future After the 2029 Flyby
After successfully collecting data during the 2029 flyby, OSIRIS-APEX has enough fuel to potentially visit other asteroids. However the most likely outcome is an extended mission orbiting Earth to enable long-term comparison studies with Apophis.
In 2036, Apophis will make another close approach allowing ground assets to make follow-up asteroid change detection measurements. If still operational in 2036, OSIRIS-APEX would provide the complementary space platform to connect these newer ground observations to the up-close 2029 baseline dataset. Such before-and-after change detection over decades could offer insights into space weathering processes difficult to study on such short timescales.
Before entering Earth orbit in 2030 however, NASA may task OSIRIS-APEX with a flyby of asteroid 2001 CC21 – which also makes a close approach to Earth in 2029 just months after Apophis. A bonus flyby of CC21 would further maximize the science return on this ambitious mission to characterize near-Earth asteroids.
Conclusion: Paving the Way for Future Planetary Defense
The launch of OSIRIS-APEX represents a major milestone in understanding potentially hazardous near-Earth asteroids. The knowledge gained from exploring Apophis up close during its 2029 flyby will bring invaluable insights that inform both impact modeling efforts and future asteroid deflection technologies.
As countries around the world ramp up plans to demonstration asteroid deflection methods over the next decade, the OSIRIS-APEX mission serves as a shining example of how scientific curiosity and planetary defense go hand in hand. 2029 will certainly be an exciting year for asteroid science – and thanks to this mission – NASA is now poised to collect groundbreaking observations leading up to and during this rare close encounter event.
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