After decades of work and more than 2 billion miles of travel, a Tucson-born space mission is poised to make a few seconds of history on Tuesday afternoon.
If everything goes according to plan, the OSIRIS-REx spacecraft will touch the surface of the asteroid Bennu at 3:12 p.m. Tucson time Tuesday, Oct. 20, and linger there for about 10 seconds — just long enough to collect a few ounces of pebbles and dirt.
The unmanned craft the size of a passenger van will then rocket safely back into orbit around the asteroid, as the University of Arizona-led team monitors its progress from more than 206 million miles away.
“I’m very excited,” said the UA’s Heather Enos, deputy principal investigator for OSIRIS-REx, during a news conference Monday. “I’ve been working on this mission for 12 years to date.”
The NASA television network will broadcast Tuesday’s touch-and-go live from the mission’s operation center at Lockheed Martin, in the Denver suburb of Littleton, Colorado. The event will also be carried online at nasa.gov/nasalive.
The OSIRIS-REx website (asteroidmission.org) will provide simulated views of the spacecraft as it moves through each step of the process starting at 10:25 a.m.
Because of an 18-minute communication delay between the Earth and Bennu, the spacecraft will guide itself to the surface using a command sequence that was uploaded into its onboard computer in advance.
When the craft gets close enough to the boulder-strewn collection site, its 11-foot sampling arm will reach down and touch the surface with a disc resembling the air filter from a classic car. A blast of nitrogen will be used to stir up the surface, sending dust and small rocks into the collection disc.
The team from the UA, Lockheed Martin and NASA’s Goddard Space Flight Center will only get basic telemetry — beamed back at a rate far slower than a text message — as OSIRIS-REx moves through the series of maneuvers.
The craft is slated to transmit a more detailed report — including photos and video — on Wednesday, Oct. 21.
It could take more than a week for the team to determine if the sampling mission was a success.
OSIRIS-REx principal investigator and UA professor Dante Lauretta said they will examine footage from the spacecraft’s sampling camera to see if the arm made good contact with the surface and what happened when the compressed nitrogen gas was triggered.
They will also visibly inspect the sampling disc using one of the spacecraft’s other cameras and conduct a spin maneuver to estimate the approximate mass of the asteroid debris collected.
Though the craft can hold more than 4 pounds of dirt and rocks up to the size of a nickel, the goal of the mission is to return to Earth with at least 60 grams — or just over 2 ounces — of material left over from the formation of the planets some 4.5 billion years ago.
Scientists believe the rocks and dust could provide clues about the origins of life and the solar system.
If the spacecraft fails to collect enough material Tuesday, the team could try again at the same location or a backup site.
OSIRIS-REx is scheduled to leave Bennu sometime next spring and return to Earth with its precious cargo Sept. 24, 2023.
The spacecraft was launched in 2016 and entered orbit around Bennu at the end of 2018, after a 1.25 billion-mile journey to chase down the asteroid. Since then, OSIRIS-REx has traveled another 1 billion miles.
The mission marks the first U.S.-led attempt to pick up a sample of pristine material from an asteroid.
In 2019, the Japan Aerospace Exploration Agency’s Hayabusa2 spacecraft collected tiny fragments from the asteroid Ryugu.
That unmanned spacecraft is scheduled to return to Earth this year.
