It will take the craft nearly 2 1/2 years to get back to Earth.
(CN) — The first NASA spacecraft scheduled to bring asteroid samples to Earth has begun the long journey home, four years after reaching the ancient asteroid Bennu. The craft carries rock and sediment from the asteroid, which could strike our planet in the late 22nd century.
After a two-year, 76-million-mile journey from Earth, NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer craft — Osiris-Rex for short — reached the diamond-shaped Bennu asteroid on Dec. 3, 2018.
The nearly 5,000-pound NASA spacecraft has sent back stunning images of Bennu’s large boulder-studded face and its massive collection of iron ore and clay minerals.
Weeks after reaching the ancient rock, the robotic explorer became the first U.S. spacecraft to orbit such a small celestial body.
The asteroid — which once formed part of the main asteroid belt between Mars and Jupiter — is estimated to be just 1,600 feet wide.
Last year, a Japanese spacecraft delivered rock samples to Earth from another asteroid named Ryugu. Both Bennu and Ryugu are considered potentially hazardous asteroids, with Bennu considered a high risk of hitting Earth in the late 22nd century.
First discovered in 1999 by NASA, Bennu is named after ancient Egypt’s mythological heron and the sun god Ra, the deity representing creation. Osiris is the god of the afterlife.
The SUV-sized Osiris-Rex craft briefly touched down on Bennu on Oct. 20, 2020, shoveling about 2 ounces of sediment and rock samples from a site named Nightingale, according to NASA.
Last week, the spacecraft completed its last flyover of Bennu and began its drift away from the space rock.
On Monday, Osiris-Rex turned toward Earth and ignited its engines for the long journey home. When it completes the mission on about Sept. 24, 2023, the craft will have brought the first asteroid samples delivered to our planet by the U.S. space agency.
But when it reaches Earth, Osiris-Rex won’t land. Instead, a capsule containing the Bennu sediment sample will deploy to Earth by parachute while the craft continues on for a journey around the sun.
NASA scientists are eager to inspect the samples from Bennu, which is expected to contain evidence of cosmic conditions at the dawn of our solar system 4.5 billion years ago.
Materials from the early solar system preserved in Bennu’s body could help planetary scientists better understand how the universe formed.
The mission — developed by scientists at the University of Arizona — could also help NASA understand potential threats asteroids may pose to Earth should they impact our planet in the future.
Researchers said in a 2020 study the asteroid may have once been part of a larger planet or protoplanet and the bright lines on its surface potentially point to a past proximity to flowing water.