The first pictures from the OSIRIS-REx probe’s brief touchdown on the asteroid Bennu have boosted scientists’ confidence that they’ll be getting a good sample of out-of-this-world dust and gravel when the spacecraft swings back to Earth.
“We really did kind of make a mess on this asteroid, but it’s a good mess,” the University of Arizona’s Dante Lauretta, principal investigator for the $800 million NASA mission, said today during a news briefing at which the imagery was released.
The image sequence shows OSIRIS-REx’s arm smashing a foot-wide, circular sample collection head — known as the Touch-and-Go Sample Acquisition Mechanism, or TAGSAM — down into Bennu’s crumbly surface, more than 200 million miles from Earth. The impact, and a well-timed blast of nitrogen gas, sent bits of material flying into space.
Based on an analysis of the images, the collection head penetrated about an inch (2 centimeters) beneath the surface, shattering a rock in the process. “Literally, we crushed it,” Lauretta said.
The collection head was designed to snare some of the material that was ejected during the touch-and-go. It was in contact with Bennu’s surface for only six seconds, but the probe’s performance during the maneuver was “as good as we could have imagined,” Lauretta said.
That’s good news for OSIRIS-REx’s scientists and engineers, who have been tasked with bringing back at least 60 grams (2 ounces) of material from the asteroid in 2023.
The van-sized OSIRIS-REx spacecraft was launched in 2016 and arrived at the roughly 1,600-foot-wide asteroid two years ago. The Oct. 20 operation marked the first time NASA tried grabbing a sample of an asteroid for return to Earth. (The Japanese have done it twice in the past 15 years.)
Scientists hope the fresh sample of material from a multibillion-year-old asteroid will bring new insights about the origins of the solar system and the chemical precursors of life.
“Origins” is the first word in the phrase that forms OSIRIS-REx’s Egyptian-sounding acronym: “Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer.” The mission is also designed to help scientists figure out what kinds of resources could be extracted from asteroids, and what strategies would work best if a potentially hazardous asteroid ever had to be diverted.
In order to gauge the success of the sample collection effort, OSIRIS-REx’s team had to wait for imagery and data to be transmitted overnight. Lauretta said the crucial images were received at Lockheed Martin’s Mission Support Area near Denver at 2 a.m. and assembled into a video showing the full sampling operation.
“I must have watched it about a hundred times,” Lauretta said.
Just after the touch-and-go maneuver, the spacecraft began backing away from the asteroid surface. It’s due to go into a holding pattern at an altitude of about 50 miles (80 kilometers) on Oct. 23.
Although the initial indications look good, scientists aren’t yet certain whether the operation grabbed enough of a sample to satisfy the mission requirements.
In the days ahead, they’ll turn the sampling arm toward the spacecraft and capture imagery of the inside of the sample collection head. They’ll also spin the spacecraft and measure changes in its moment of inertia, to estimate how much extra mass is now being carried.
If scientists determine that less than 60 to 80 grams of material was collected, they could try again at a different site on the asteroid’s surface in January. But if they’re good to go, OSIRIS-REx will start heading back toward Earth next March, and drop off the sample capsule over Utah in 2023.
Lauretta said he hasn’t gotten much rest over the past few days. “Science never sleeps in these kinds of conditions,” he said.
Now he’s ready for a change.
“The only thing I’m looking forward to is maybe being able to sleep well tonight, knowing that we’ve had a job really well done,” he said.