NASA's Historic Asteroid Space Probe will return to Earth after 7 years

In 2016 the US space probe OSIRIS-REx launched...

NASA's first mission to retrieve an asteroid sample and return it to the US is expected to reach a perilous finale on Sunday with a descent into the Utah desert.

Scientists hope the material possibly the most ever retrieved by such a mission will provide humanity with a better understanding of the formation of our solar system and how Earth became habitable.

In 2016 the US space probe OSIRIS-REx, launched, scooped up the sample from an asteroid called Bennu almost three years ago.

Touchdown is scheduled for Sunday at around 9:00 am local time (1500 GMT), at a military testing site in the western state.

Some four hours earlier, at about 67,000 miles (108,000 kilometers) away from Earth, the Osiris-Rex probe will release the capsule containing the sample.

The final descent lasts 13 minutes: the capsule enters the atmosphere at a speed of around 27,000 miles (43,000 kilometers) per hour and reaches a maximum temperature of 5,000 degrees Fahrenheit (2,800 degrees Celsius), NASA said.

If all goes well, two successive parachutes will bring the capsule to a soft landing on the desert floor, where it will be retrieved by prepositioned staff.

Hitting the target area of 250 square miles (650 square kilometers) is like "throwing a dart across the length of a basketball court and hitting the bullseye," Rich Burns, OSIRIS-REx project manager at NASA, told a press conference last month.

The night before landing, controllers will have a final opportunity to abort if conditions are not correct. If so, the probe would then circle the Sun before its next attempt -- in 2025.

Sample return missions are hard. There's a number of things that can go wrong," said Sandra Freund, Lockheed Martin's OSIRIS-REx program manager.

Teams have meticulously prepared for the capsule's return -- even a "hard landing scenario" according to Freund -- in order to preserve the asteroid material in its pristine form.

A final dress rehearsal took place in August, with a replica capsule dropped from a helicopter.