NASA OSIRIS-REx Returning to Earth With Asteroid Samples

After accomplishing its mission on Asteroid Bennu, NASA's OSIRIS-REx spacecraft has departed from the giant rock and is set to return to Earth carrying the samples it collected.

The NASA asteroid study and sample return mission, whose full name translates to Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, officially started the final phase of its mission on Monday, May 9, 1:23 PM PST. Igniting its boosters for about seven minutes, OSIRIS-REx has begun moving away from its orbit around asteroid Bennu before recalibrating for its homebound flight.

Its sample, which will be studied once returned to Earth, is a 2.1 ounce (60 grams) asteroid rock and soil from the asteroid. The sample is expected to be airdropped at the Utah Test and Training Range on September 24, 2023.

"OSIRIS-REx's many accomplishments demonstrated the daring and innovate way in which exploration unfolds in real time," said Thomas Zurbuchen, NASA's associate administrator for science.

According to NASA, OSIRIS-REx "exceeded many expectations," the latest being its successful collection of the soil samples from the asteroid's surface.

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Final Phase of a Seven-Year Mission

OSIRIS-REx was first launched on September 8, 2016 via an Atlas V rocket (made by ULA) from Space Launch Complex 41 at Cape Canaveral. Three months into space, on December 28, 2016, the spacecraft began its first deep-space maneuver to change its trajectory. It ended its cruise phase upon contact with Bennu in December 2018, starting the science and sample collection phase of its mission.

After matching the speed and orbit of Bennu, it started passing through the asteroid at increasingly shorter distances, fine-tuning the shape and the orbit of the giant space object. Its survey of Bennu reached the asteroid by as close as 0.62 miles (1 kilometer).

In preparation for its collection phase, OSIRIS-REx first conducted rehearsals, preparing its solar arrays to be raised at a particular angle to prevent it from accumulating dust and provide better clearance to the sections of the spacecraft below.

Afterwards, its Touch-and-Go Sample Acquisition Mechanism (TAGSAM) began the collection of the sample with a sample head on the end of a robotic arm.

Marking the largest space sample brought back to earth by NASA mission since the Apollo mission, the OSIRIS-REx souvenir will only use a small part of the collected materials for immediate study. Parts of the collected sample will be sent to other laboratories around the world, while a part of the collected samples will be set aside for future studies.

About Asteroid Bennu

Formally tagged as 101955 Bennu, the provisional designation being 1999 RQ36, the Asteroid that has hosted OSIRIS-REx for the past few years is a C-type (carbonaceous) asteroid first discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) project back in September 1999.

Bennu has a mean diameter of about 1,610 feet (490 meters) throughout its loosely round shape. Although initial Earth-based observations made it look like the asteroid has a generally smooth surface, higher-resolution observations sent back by OSIRIS-REx show that the asteroid surface is rougher, housing more than 200 boulders measuring more than 10m from the surface.