It’s not graffitti in space. The OSIRIS-REx mission is returning a large sample of an ancient asteroid to Earth.

Credit: NASA/Goddard/University of Arizona

On October 20, 2020, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) spacecraft unfurled its robotic arm, and in a first for the agency, briefly touched an asteroid to collect dust and rocks from the surface for delivery to Earth in 2023. The maneuver is called “Touch-And-Go” or TAG.

This well-preserved, ancient asteroid, known as Bennu, is currently more than 200 million miles (321 million kilometers) from Earth. Bennu offers scientists a window into the early solar system as it was first taking shape billions of years ago and flinging ingredients that could have helped seed life on Earth. It has a very dark surface and is classified as a B-type asteroid. Such asteroids are considered “primitive”, having undergone little geological change from their time of formation nearly 4.6 billion years ago.

Bennu may contain molecular precursors to the origin of life and the Earth’s oceans. It is also one of the most potentially hazardous asteroids, as it has a probability of impacting the Earth late in the 22nd century.

“This amazing first for NASA demonstrates how an incredible team from across the country came together and persevered through incredible challenges to expand the boundaries of knowledge,” said NASA Administrator Jim Bridenstine. “Our industry, academic, and international partners have made it possible to hold a piece of the most ancient solar system in our hands.”

At 1:50 p.m. EDT, OSIRIS-REx fired its thrusters to nudge itself out of orbit around Bennu. It extended the shoulder, then elbow, then wrist of its 11-foot (3.35-meter) sampling arm, known as the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), and transited across Bennu while descending about a half-mile (805 meters) toward the surface. After a four-hour descent, at an altitude of approximately 410 feet (125 meters), the spacecraft executed the “Checkpoint” burn, the first of two maneuvers to allow it to precisely target the sample collection site, known as “Nightingale.” After the sample, the spacecraft rapidly left the surface and began the long journey back home.



The spacecraft captured images of its own sample collector head as it moved through several different positions. In reviewing these images, the OSIRIS-REx team noticed both that the head appeared to be full of asteroid particles, and that some of these particles appeared to be escaping slowly from the sample collector, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) head. They suspect bits of material are passing through small gaps where a mylar flap – the collector’s “lid” – is slightly wedged open by larger rocks. The OSIRIS-Rex team will now focus on stowing the sample in the Sample Return Capsule (SRC), where any loose material will be kept safe during the spacecraft’s journey back to Earth.

The name Bennu was selected from more than eight thousand student entries from dozens of countries around the world who entered a “Name That Asteroid!” contest run by the University of Arizona, The Planetary Society, and the LINEAR Project in 2012. Third-grade student Michael Puzio from North Carolina proposed the name in reference to the Egyptian mythological bird Bennu.

OSIRIS-REx launched from Cape Canaveral Air Force Station in Florida Sept. 8, 2016. It arrived at Bennu Dec. 3, 2018, and began orbiting the asteroid for the first time on Dec. 31, 2018. It took over a year to find a safe landing site. The spacecraft is scheduled to return to Earth Sept. 24, 2023, when it will parachute the SRC into Utah’s west desert where scientists will be waiting to collect and study the asteroid sample.

OSIRIS is the 3rd asteroid sample mission. The Japanese probe Hayabusa returned samples from 25143 Itokawa in 2010, and Hayabusa2 will return from 162173 Ryugu in December 2020. They traveled to closer objects with a small sample size.

NASA also has a collection of free mission posters, including space Valentines, We have three of them here, but there’s a lot more where that came from.

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