NASA Spacecraft Carrying Asteroid Sample Starts 2.5-Year Earthbound Journey

When it arrives on Earth, it could reveal some of the solar system's oldest secrets.
Chris Young

A NASA spacecraft, called OSIRIS-REx, which collected samples from the asteroid Bennu 200 million miles (320 million km) away from Earth, started a two-and-a-half-year voyage back to our planet on Monday, May 10, a press statement from NASA explains.

The May 10 departure date was chosen specifically as it coincided with the asteroid Bennu's closest alignment to Earth as it travels through our solar system.

At 16:23 EDT (20:23 UTC) on May 10, the spacecraft fired its main engines full throttle for seven minutes, powering the spacecraft away from Bennu at 600 mph (almost 1,000 km/h).

Staff cheered — in similar scenes to those seen for NASA's first controlled flight on Mars by its Ingenuity helicopter — when the OSIRIS-REx launched off the asteroid, roughly three years after it first arrived in 2018, with the event live streamed on NASA's YouTube channel.

Investigating the early years of our solar system

The OSIRIS-REx mission — the acronym stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer — launched in 2016 with the goal of latching onto Bennu to collect samples that could potentially help the scientific community discover more about the early days of our solar system.

"We have a primordial piece of our solar system headed back to Earth where many generations of researchers can unlock its secrets," said Thomas Zurbuchen, associate administrator for science at NASA Headquarters.

NASA Spacecraft Carrying Asteroid Sample Starts 2.5-Year Earthbound Journey
A picture of asteroid Bennu taken by OSIRIS-REx as it pushed away from the space rock on May 10, 2021. Source: NASA

Asteroids are essentially debris from the solar system's formation approximately 4.5 billion years ago, meaning their chemical composition acts as a window into the very distant past.

As per Dr. Jason Dworkin, NASA Project Scientist on the Bennu mission, asteroids are remnants of the early solar system, so the OSIRIS-REx mission's survey of asteroid Bennu, as well as its sample collection of pebbles and dust, could help to reveal vital hints as to how life formed in the early solar system.

OSIRIS-REx successfully completed its mission objective on Bennu

The mission's most critical moment occurred in October 2020, after the OSIRIS-REx unfurled an 11-foot (3.35 meter) sampling arm known as Touch-And-Go Sample Acquisition Mechanism (TAGSAM).

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NASA announced that same month the spacecraft sampling arm collected more than enough to meet one of its main mission requirements of acquiring at least 2 ounces (60 grams) of material from the asteroid.

NASA Spacecraft Carrying Asteroid Sample Starts 2.5-Year Earthbound Journey
Footage captured by OSIRIS-REx of its sampling arm collecting material in October 2020. Source: NASA

The mission also found trace amounts of hydrogen and oxygen on the asteroid's rocky surface, principal ingredients for water, and therefore life.

Following the news of the successful launch away from Bennu, Apollo 11 astronaut Buzz Aldrin tweeted "congratulations to both NASA and the OSIRIS-REx team on a successful sample-collecting mission – the first since the Apollo program! Looking forward to learning more about the asteroid material you collected!"

A long journey awaits for OSIRIS-REx

The OSIRIS-REx spacecraft will now travel towards Earth on a two-and-a-half-year trip guided mainly by the Sun's gravity. The spacecraft will orbit the Sun twice before reaching Earth on Sept. 23, 2023.

When it reaches Earth, a capsule containing the samples from Bennu will separate from the spacecraft and enter Earth's atmosphere, where it will deploy a parachute and land on the Utah Test and Training Range in Utah's West Desert, with scientists on standby for the retrieval.

NASA will actually be the second organization to bring a substantial asteroid sample back to Earth after Japan's JAXA. Following a six-year journey, the Hayabusa-2 mission returned a sample from the asteroid Ryugu in a "perfect" state last year.

JAXA also brought a smaller sample back to Earth with its Hayabusa-1 mission, with scientists subsequently discovering water and organic matter in the samples.

NASA explained that the OSIRIS-REx samples will be distributed to research organizations worldwide, though the majority (75 percent) of the sample will be preserved at the Johnson Space Center in Houston for future scientists to study using tools and methods that have not yet been invented. 

Editor's note 12/05/21: This article was updated to include the image of asteroid Bennu taken by OSIRIS-REx as well as Buzz Aldrin's tweet congratulating NASA, both of which were published shortly after the article was originally published.