Washington, Oct 30 (IANS): NASA on Friday said that its OSIRIS-REx spacecraft has completed the most challenging phases of its mission after it successfully stowed samples of asteroid Bennu.

The mission team sent commands to the spacecraft on Wednesday, instructing it to close the Sample Return Capsule (SRC).

NASA decided to expedite sample stowage, originally scheduled for November 2, in the spacecraft's SRC after the OSIRIS-REx mission team received images on October 22 that showed the spacecraft's collector head overflowing with material collected from Bennu's surface -- well over the 60-gram mission requirement.

The mission team then decided to go with early stowage to minimise further sample loss.

"This achievement by OSIRIS-REx on behalf of NASA and the world has lifted our vision to the higher things we can achieve together, as teams and nations," said NASA Administrator Jim Bridenstine.

"Samples like this are going to transform what we know about our universe and ourselves, which is at the base of all NASA's endeavours."

As of late October 28, the sample of Bennu is safely stored and ready for its journey to Earth, NASA said.

"I'm very thankful that our team worked so hard to get this sample stowed as quickly as they did," said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

"Now we can look forward to receiving the sample here on Earth and opening up that capsule."

The OSIRIS-REx team will now focus on preparing the spacecraft for the next phase of the mission - Earth Return Cruise.

The departure window opens in March 2021 for OSIRIS-REx to begin its voyage home, and the spacecraft is targeting delivery of the SRC to Earth on September 24, 2023.