Chapter 1: Introduction to OSIRIS-REx

While the world focused on the Perseverance rover's journey to Mars, NASA's asteroid sampling mission was preparing for its significant moment. The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (commonly known as OSIRIS-REx) has successfully finished its final test approach towards the surface of asteroid Bennu. During its next descent, OSIRIS-REx will gather samples from Bennu to bring back to Earth.

In 2016, NASA launched OSIRIS-REx, directing it to intercept the carbon-rich asteroid 101955 Bennu, which measures approximately 1,610 feet (490 meters) in diameter. Bennu orbits near Earth at times, presenting a slight risk of impact over the coming centuries. At present, it remains a safe distance away, about 2 astronomical units (AU) from Earth (1 AU being the distance from Earth to the sun).

OSIRIS-REx reached Bennu in 2018, and the team immediately began searching for suitable landing zones. They faced challenges similar to those encountered by Japan’s Hayabusa2 mission, discovering that Bennu's surface was far more rugged than anticipated. To collect a sample, OSIRIS-REx must make contact with the uneven terrain, which poses risks due to rocky outcrops. Eventually, NASA identified multiple potential landing sites, naming them after birds, with the Nightingale site, located in a crater near Bennu's north pole, being chosen as the primary target.

On August 11th, OSIRIS-REx completed its second rehearsal for the actual sampling attempt. The spacecraft ignited its engines to exit the "safe home orbit" and descended to approximately 410 feet (125 meters) above Bennu's surface. As it approached, OSIRIS-REx synchronized its rotation with that of Bennu and reached an altitude of just 131 feet (40 meters) above the Nightingale site. The video above illustrates this descent, showcasing Nightingale appearing at the top of the frame near the conclusion of the flight. At that moment, the engines were activated again to return OSIRIS-REx to a safe orbit.

With the practice runs concluded, the team is now concentrating all efforts on the sample collection operation scheduled for October 20th. On that day, OSIRIS-REx will descend to the surface of Bennu, using its sampling arm to collect material. A burst of nitrogen gas will, ideally, propel particles from Bennu into the sample container. NASA aims to gather approximately 60 grams of material from the asteroid. Following this collection, OSIRIS-REx will embark on its journey back to Earth, with the return capsule expected to land in September 2023.

Chapter 2: Upcoming Milestones

In this chapter, we will explore the key milestones ahead for the OSIRIS-REx mission, including the planned sample return and its implications for science and planetary defense.

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