UA-led asteroid mission announces May 10 departure date for spaceship's return trip to Earth

The University of Arizona-led mission announced plans Tuesday to send the unmanned probe on a final pass by the asteroid Bennu to gather some high-resolution pictures before heading home with its precious payload of rock samples.

Mission spokeswoman Erin Morton said the spacecraft was originally scheduled to head for home as soon as its departure window opens in March, but the team has since plotted out a new, more efficient return route. By waiting until May 10, the spaceship will save more than enough fuel for one last approach to the asteroid, while still arriving back at Earth as planned on Sept. 24, 2023.

The proposed flyby in early April will give researchers a look at the scars left on Bennu’s surface when the probe successfully touched down there in October.

The sampling arm on OSIRIS-REx made contact with the surface for about six seconds, just long enough to blast the asteroid with compressed nitrogen gas and send up a cloud of debris so big it surprised even the experts.

Morton said the mission team just couldn’t pass up a chance to study the physics and the fallout of that man-made explosion one last time before heading home.

OSIRIS-REx has been slowly drifting away from Bennu since it made contact with the asteroid on Oct. 20. It is now about 1,250 miles from the spinning top of space rock.

The planned flyby would bring the craft back to within about 2 miles of Bennu.

The maneuver will also give the team a chance to test the spacecraft’s cameras and other scientific equipment to see if it was clogged with dust during the sample collection maneuver. If the instruments are sufficiently clean, OSIRIS-REx could be sent on a bonus mission to a second asteroid after its scheduled rendezvous with Earth in 2023.

First, though, the spaceship must complete its primary objective.

The goal of NASA’s first-ever asteroid sampling mission is to return to Earth with at least 60 grams — or just over 2 ounces — of pristine dust and pebbles that date back roughly 4.5 billion years and could hold clues to the formation of the solar system and the origins of life.

Team members believe they collected well over 60 grams of material. Those samples are now sealed away inside a return capsule roughly the size of a pizza box, which eventually will be jettisoned into Earth’s atmosphere to parachute down to a designated landing site inside the U.S. Air Force’s massive Utah Test and Training Range west of Salt Lake City.

Recovery of the return capsule will mark the end of the OSIRIS-REx mission, but the spacecraft could be sent out again with NASA’s approval.

One possible target is an asteroid called Apophis, which is expected to pass within 20,000 miles of Earth in April 2029.

UA planetary scientist Dante Lauretta, who heads up the OSIRIS-REx mission as its principal investigator, recently told the website Space.com that the spacecraft could be put into orbit around Apophis roughly a week after its near miss of Earth.

There would be no sample collection the second time around, but the probe could beam back high-resolution images and other data from the asteroid, just as it did of Bennu.

“But that’s all hypothetical,” Morton said of a possible trip to Apophis or elsewhere. “We’re so far away from actually looking at another mission. We need to get home first.”

Right now, OSIRIS-REx is approximately 205 million miles away from Earth, on the opposite side of the sun.