Over two-years after launch, the NASA probe OSIRIS-REx will arrive at a skyscraper-sized asteroid for the first US mission to carry asteroid samples back to earth.
The over $US800 million ($A1.1 billion) undertaking will provide pristine asteroid samples necessary for studying the early solar system, NASA says, and it will allow scientists to better understand the flight paths of potentially hazardous asteroids.
OSIRIS-REx is scheduled to rendezvous with the asteroid, known as Bennu, around 4am on Tuesday (AEDT). The landing will be live-streamed on the NASA website.
The spacecraft was launched from Florida in September 2016 and has since hurled through space at speeds of over 100,000km/h.
After extensive observation and mapping throughout next year and into 2020, the space probe will extend a probe to the surface to collect a sample of up to 2 kilograms.
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One of the key goals of the OSIRIS-REx mission is to study the impact of the sun's heat on the orbits of asteroids with the potential to hit Earth and cause substantial damage.
Bennu - named after a mythological Egyptian deity by a third-grade contest winner - is one of the most hazardous asteroids known to NASA because of its large size and orbit.
The chances of Bennu striking earth are still a fraction of a per cent.
