CAPE CANAVERAL, FLORIDA – On Monday, a NASA spacecraft fired its engines and began the long trip back to Earth, leaving the ancient space rock in its rearview mirror, with debris from an asteroid hidden inside.
Osiris-Rex, the robotic prospector, would take two years to return home.
Dante Lauretta, the principal scientist at the University of Arizona, figures that the spacecraft carries between a half pound and a pound (200 grams and 400 grams) of mainly bite-size chunks. It comfortably passes the target of at least 2 ounces in either case (60 grams).
That will be the United States’ first cosmic haul since the Apollo moon rocks. NASA has previously returned comet dust and solar wind samples, but this is the first time it has gone after asteroid fragments. Japan has done so twice, but only in small numbers each time.
Monday’s departure from Bennu’s neighborhood was characterized as bittersweet by scientists.
“I’ve been trying to get a sample back from an asteroid since my daughter was in diapers, and now she’s graduating from high school, so it’s been a long road,” NASA project scientist Jason Dworkin said.
“We’ve grown used to being at Bennu and seeing fresh and thrilling photographs and data flowing back to us here on Earth,” Lauretta said.
When news of the spacecraft’s departure came, Lockheed Martin flight controllers in Colorado ecstatically exclaimed, “We’re taking the samples along!”
Scientists expect that the samples vacuumed last October from Bennu’s dark, rugged, carbon-rich soil would reveal some of the solar system’s secrets. The asteroid is 4.5 billion years old and measures 1,600 feet (490 meters) in diameter.
Bennu, a fractured chunk of a larger asteroid, is thought to contain the solar system’s intact building blocks. The returned fragments may provide insight into the formation of planets and the origins of life on Earth. They can also increase Earth’s chances of surviving any incoming rocks.
Osiris-Rex will bring another 1.4 billion miles (2.3 billion kilometers) on the odometer to catch up with Earth, despite being 178 million miles (287 million kilometers) distant.
The SUV-sized spacecraft would complete two orbits around the sun before deploying its tiny sample capsule to Utah’s desert floor on Sept. 24, 2023, bringing the mission’s $800 million budget to a close. In 2016, it took off from Cape Canaveral.
The priceless samples will be stored at NASA’s Johnson Space Center in Houston, which still houses hundreds of pounds of lunar content obtained by the 12 Apollo moonwalkers between 1969 and 1972.
Scientists originally estimated that the spacecraft held 2 pounds (1 kilogram) of asteroid debris, although they have since updated their estimation. They won’t know for sure how much is on board until after the capsule has landed.
Dworkin said, “Any bit of sample is useful.” “We’ll have to wait.”
Lucy, a spacecraft set to launch in October, will sail past swarms of asteroids near Jupiter, while Dart, a spacecraft set to launch in November, will aim to divert an asteroid as part of a planetary defense drill. The Psyche spacecraft will then launch in 2022 for an odd, metallic asteroid of the same name. None of these missions, though, include the return of samples.