NASA has embarked on an ambitious new mission to explore the asteroid Apophis, launching a spacecraft named OSIRIS-APEX that will rendezvous with the asteroid in 2029. OSIRIS-APEX recently completed a mission to the asteroid Bennu, where it collected sample materials to bring back to Earth. Now the intrepid spacecraft has a new destination in its sights.
OSIRIS-REx Spacecraft Re-Tasked for New Mission
Originally named OSIRIS-REx, the spacecraft successfully operated around the asteroid Bennu for over two years before finally collecting samples from its surface in October 2020. It then began the long journey back to Earth to deliver the precious asteroid material for detailed analysis. However, mission planners at NASA decided to take advantage of the spacecraft’s fully functioning state and utilize it for another adventure, rather than let it drift lifelessly after delivering its cargo.
As OSIRIS-REx neared Earth in September 2023, engineers performed a precisely choreographed operation to redirect its trajectory towards Apophis. While still over 17 million miles away, the spacecraft fired its thrusters for over 10 minutes to adjust its approach angle and speed into Earth’s gravitational field. This would enable OSIRIS-REx to use Earth’s gravity to slingshot itself towards Apophis, saving time and fuel.
The maneuver was a resounding success, committing OSIRIS-REx to its new mission while still ensuring safe delivery of the precious Bennu samples. In mid-December, the spacecraft zoomed by Earth, providing some outstanding views of our planet while picking up the speed boost needed to reach Apophis in 2029.
OSIRIS-REx Re-Christened OSIRIS-APEX
With the major trajectory correction burn behind it and Earth receding in its figurative rearview mirror, NASA decided to give OSIRIS-REx a name more fitting of its ambitious new mission: OSIRIS-APEX. APEX stands for “Apophis Explorer”, encapsulating the spacecraft’s next adventure of investigating the enigmatic Apophis asteroid over a period of more than two years.
While in orbit around Apophis, OSIRIS-APEX will thoroughly characterize the asteroid’s shape, interior structure, composition, and orbital trajectory to gather critical data for evaluating any impact hazards Apophis may pose in the future.
|Original Spacecraft Name
|New Spacecraft Name
OSIRIS-APEX is equipped with an array of high-tech instruments ideal for mapping the asteroid’s surface geology and interactions with solar radiation pressure, while also measuring any subsurface distortions caused by gravitational tides from the Sun and planets. Radio tracking of OSIRIS-APEX while orbiting Apophis will enable precise refinements of the asteroid’s orbit.
Asteroid Apophis Poses Minimal Impact Risk
Discovered in 2004, asteroid 99942 Apophis quickly gained notoriety after initial orbital calculations indicated it had a small chance of hitting Earth in 2029 or later encounters. While an actual impact has been ruled out during the 2029 close approach, when Apophis will come within 20,000 miles of Earth’s surface, scientists want to improve their understanding of subtle orbital effects that could influence Apophis’ trajectory over centuries or millennia.
Recent radar observations during Apophis’ past close approaches in 2013 and 2029 have helped reduce uncertainties in its orbit, enabling NASA scientists to rule out any Earth impact over the next 100+ years. However, many unknowns still exist. By making precise in situ measurements from orbit around Apophis, OSIRIS-APEX will directly sample the asteroid’s weak but cumulative gravitational tug and minute pressure effects from solar radiation reflecting off its craggy surface. Such firsthand data will reduce key uncertainties in Apophis’ orbit by an order of magnitude over existing indirect observations from afar.
While Apophis still has an infinitesimally small chance of eventually hitting Earth many decades or centuries down the road due to these subtle effects, the OSIRIS-APEX mission will greatly shrink any residual uncertainties and enable calculations that extend farther into the future before losing precision.
Unique Opportunity for OSIRIS-APEX Mission
The OSIRIS-APEX mission offers an extremely rare opportunity for the spacecraft to rendezvous with Apophis. After 2029, Apophis will not pass this close to Earth again for over a century. By taking advantage of the precisely aligned trajectories of Earth, Apophis, and itself, OSIRIS-APEX can reach Apophis using minimal fuel in time for a 2029 launch window. Catching this launch window will enable several years of orbiting and studying Apophis before the asteroid ventures deeper into space once again.
|Apophis Orbit Close Approaches
|Distance from Earth
|Within 20,000 miles
|Over 2 million miles
In preparation for orbital operations starting in late 2029, OSIRIS-APEX will approach Apophis along its orbital path around the Sun, gradually matching velocities for smooth transition to orbit. After delivering samples from Bennu, OSIRIS-APEX still has plenty of fuel reserves for necessary trajectory adjustments on the multi-year journey. Its solar panels can provide ample power so far from the Sun, and most original science instruments remain in good health.
Mission Science Operations at Asteroid Apophis
OSIRIS-APEX will spend over 25 months orbiting Apophis, allowing time for thorough scientific measurements, data analysis, and even a special treat. In early 2031, Apophis will make an exceptionally close flyby of Earth, around 18,600 miles above the surface. For a short time, OSIRIS-APEX will have a direct radio connection path to Earth, facilitating quick-turnaround command sequences and data delivery at up to eight times higher than when communicating around the Sun.
OSIRIS-APEX Science Instruments
|High-resolution surface imaging, mineral/rock identification via spectrometry
|Precise asteroid shape and rotational state
|Gravitational perturbations, interior structure
|Thermal Emission Spectrometer
|Surface mineral composition, thermal inertia
|Student-Built Radiation Environment Monitors
|Characterize solar/galactic particle radiation fields
While the primary mission will last until mid-2032, OSIRIS-APEX carries enough fuel to keep operating for years to come if it remains in good health. Extending operations as long as possible will provide bonus data further refining Apophis’ orbit.
Critical Experience for Future Asteroid Exploration
In addition to better understanding Apophis itself, OSIRIS-APEX will demonstrate technologies and methodologies essential for future missions focused on investigating asteroids that could pose more serious Earth impact hazards. By practicing procedures like matching orbits with irregularly shaped minor planets and observing an asteroid’s orbital trajectory over an extended timeline, OSIRIS-APEX will help validate capabilities that could one day be critical if quick action is needed to deflect an incoming asteroid.
Lessons learned from OSIRIS-APEX could also feed forward to ambitious future concepts like robotic asteroid mining operations. By launching now, OSIRIS-APEX can provide operational experience with accessing asteroid resources years before such activities become commercially viable.
The OSIRIS-APEX mission signifies both an exciting new adventure for the seasoned OSIRIS-REx spacecraft and a major milestone in humanity’s expanding capabilities for asteroid exploration. As NASA’s first mission to perform long-term monitoring of an asteroid from orbit, OSIRIS-APEX will gather invaluable data to assess and predict the trajectory of asteroid Apophis for decades and centuries while demonstrating technologies essential for planetary defense and space utilization. Like the ancient Egyptian god it was named after, OSIRIS-APEX has risen from old glories to chart a bold new journey through the cosmos.
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