A time capsule containing a sample of ancient rock and dirt that is 4.5 billion years old is on its way to Earth.
Nasa is planning for its Osiris-Rex asteroid probe to return from outer space in September 2023. On board will be a special cargo of around 60g of dust from the near-Earth asteroid Bennu.
It is the largest sample collected from outer space since the Apollo Moon missions more than 50 years ago.
Scientists believe it may provide clues on how the Solar System was formed.
The Osiris-Rex probe started its two-and-a-half-year return journey from Bennu on Monday.
The spacecraft was launched in 2016 off the coast of Florida, US.