U.S. spacecraft touches asteroid for rare rubble grab

CAPE CANAVERAL, Fla. — A NASA spacecraft descended to an asteroid Tuesday and, dodging boulders the size of buildings, momentarily touched the surface to collect a handful of cosmic rubble for return to Earth.

It was a first for the United States — only Japan has scored asteroid samples.

“I can’t believe we actually pulled this off,” said lead scientist Dante Lauretta of the University of Arizona. “The spacecraft did everything it was supposed to do.”

The Osiris-Rex spacecraft sent back confirmation of its contact with asteroid Bennu more than 200 million miles away, drawing cheers from the mission team. But it could be a week before scientists know how much, if anything, was grabbed and whether another try will be needed. If successful, Osiris-Rex will return the samples in 2023.

Following commands sent well in advance by ground controllers near Denver, the spacecraft took 4 ½ hours to make its way down from its tight orbit around Bennu.

Bennu’s gravity was too low for the spacecraft to land — the asteroid is 1,670 feet across. As a result, Osiris-Rex had to reach out with its 11-foot robot arm while dodging boulders the size of buildings and attempt to grab at least 2 ounces of Bennu.

It promised to be the most harrowing part of the mission, which began with a launch from Cape Canaveral in 2016.

“We’ll only be kissing the surface with a short touch-and-go measured in just seconds,” said the University of Arizona’s Heather Enos, the deputy scientist for the mission.

A van-sized spacecraft with an Egyptian-inspired name, Osiris-Rex aimed for a spot equivalent to a few parking spaces on Earth in the middle of the asteroid’s Nightingale Crater. After nearly two years orbiting Bennu, the spacecraft found this location to have the biggest patch of particles small enough to be swallowed up.

The plan called for Osiris-Rex to shoot out pressurized nitrogen gas to stir up the surface, then suck up any loose pebbles or dust. Contact was expected to last 5 seconds to 10 seconds, with the spacecraft quickly backing away.

NASA won’t know until later this week how much was actually collected — or whether the spacecraft got anything at all.

Unlike the exceptionally fast Mars descents — described by NASA as seven minutes of terror — “this is much more of 4 ½ hours of mild anxiousness,” Enos said on the eve of the big grab. “We have practiced and rehearsed with the spacecraft ... so we’ve seen almost all of this already.”

Osiris-Rex got as low as 130 feet during the final dry run in August.

By the time flight controllers near Denver hear back from Osiris-Rex, the action already will have happened 18 ½ minutes earlier, the time it takes radio signals to travel each way between Bennu and Earth.

Scientists want to get between 2 ounces and 4 pounds of Bennu’s black, carbon-rich material — thought to contain the building blocks of our solar system.

NASA’s science mission chief, Thomas Zurbuchen, likened Bennu to the Rosetta Stone: “something that’s out there and tells the history of our entire Earth, of the solar system, during the last billions of years.”

Osiris-Rex can make up to three touch-and-go maneuvers in case it comes up short. Regardless of how many tries it takes, the samples won’t return to Earth until 2023 to close out the $800 million-plus quest. The sample capsule will parachute into the Utah desert.

“That will be another big day for us. But this is absolutely the major event of the mission right now,” NASA scientist Lucy Lim said Tuesday.