NASA's OSIRIS-REx spacecraft landed in the Utah desert in the United States on Sunday, bringing samples of asteroid Bennu to Earth.

Scientists have high hopes for the sample, saying it will provide a better understanding of the formation of our solar system and how Earth became habitable.

"Touchdown of the OSIRIS-REx sample return capsule!" a commentator said on NASA's live video webcast of the landing, as engineers and team members applauded at a nearby mission control center.

Completing a 6.21-billion-kilometer journey, it marked the United States' first sample return mission of its kind, the U.S. space agency said in a post on X, formerly known as Twitter.

NASA chief Bill Nelson hailed the mission and said the asteroid dust "will give scientists an extraordinary glimpse into the beginnings of our solar system."

Launched in 2016, the OSIRIS-REx probe had landed on the asteroid Bennu and collected what NASA estimated is roughly 250 grams of dust from its rocky surface four years later.

Even that small amount, NASA said, should "help us better understand the types of asteroids that could threaten Earth."

The sample return "is really historic," NASA scientist Amy Simon told AFP. "This is going to be the biggest sample we've brought back since the Apollo moon rocks" were returned to Earth.

On Monday, the sample will head to Johnson Space Center in Houston for additional study, and NASA plans to announce its first results at a news conference October 11.

Most of the sample will be conserved for study by future generations. Roughly one-fourth will be immediately used in experiments, and a small amount will be sent to mission partners Japan and Canada.

Japan had earlier given NASA a few grains from asteroid Ryugu, after bringing about 5 grams of dust to Earth in 2020 during the Hayabusa-2 mission. Ten years before, it had brought back a microscopic quantity from another asteroid.

But the sample from Bennu is much larger, allowing for significantly more testing, Simon said.

Scientists believe Bennu, about 500 meters in diameter, is rich in carbon – a building block of life on Earth – and contains water molecules locked in minerals.

Bennu surprised scientists in 2020 when the probe, during its brief contact with the asteroid's surface, sank into the soil, revealing an unexpectedly low density, like a children's pool filled with plastic balls. 

Understanding its composition could come in handy in the future, for that there is a slight, but non-zero, chance (one in 2,700) that Bennu could collide catastrophically with Earth, though not until 2182.