They won't know the precise amount of the cosmic haul from asteroid Bennu, more than 200 million miles (322 million kilometers) away, until the capsule parachutes into the Utah desert in 2023. They moved up a maneuver to seal the collection device into a capsule created to bring it safely through Earth's atmosphere for a landing now expected in September 2023.
The spacecraft launched in 2016 and will begin its journey back to Earth next March.
Officials behind the Osiris-Rex probe, which landed on Bennu earlier this week, were anxious after a rock wedged open the door of a container.
The University of Arizona planned and leads the Osiris Rex mission. Material leaking from the collector made scientist worry the sample would be lost but controllers avoided maneuvers that might shake material out of the container.
"Even though my heart breaks for the loss of sample, it turned out to be a pretty cool science experiment and we're learning a lot", Lauretta told reporters.
The slow, tedious stowing operation took 36 hours.
I've officially closed the Sample Return Capsule!
Osiris-Rex is set to come home in September 2023, hopefully with the largest sample returned from space since the Apollo era.
Scientists believe asteroids are pristine samples of materials that will offer clues to how the solar system, and maybe life, formed. Will not depart when the planet and the earth are properly aligned. Samples can also help improve our problems, he said, if a doomsday rock is on our way.
Bennu - a black, roundish rock bigger than New York's Empire State Building - could come dangerously close to Earth late in the next decade. The odds of a strike are 1-in-2,700. The second batch is due to arrive in December.