Washington (dpa) - The US space agency is poised to launch a probe to the long-watched asteroid Bennu, which astronomers say could menace future generations on Earth.
The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft is scheduled to launch at 7:05 pm Thursday (2305 GMT) from Cape Canaveral Air Force Station, NASA said.
If delayed, the window for blastoff atop a United Launch Alliance (ULA) Atlas V rocket extends until 9:05 pm (0105 GMT Friday).
The mission is the United States' first to sample an asteroid.
The asteroid, with a diameter greater than the height of the Empire State building, was discovered in 1999 and was found to have the possibility of passing dangerously close to Earth in the 22nd century.
Though the risk to Earth is very slight, NASA still considers the rocky object one of the most dangerous known asteroids.
The spacecraft would reach Bennu in August 2018, get close enough in 2020 to scoop up a sample of between 60 and 2,000 grams using a robotic arm, then return to Earth in 2023. It will travel more than 650 million kilometres over the entire trip.
In addition to improving the understanding of asteroids that could impact Earth, the mission will help scientists investigate the solar system's evolution and the history of Bennu over the last 4.5 billion years, NASA said.