Inside a small canister 200 million miles from Earth is something that University of Central Florida physics professors Humberto Campins and Kerri Donaldson Hanna have only dreamed of: a sample of an asteroid.
NASA had never collected one until Oct. 20, when its OSIRIS-REx spacecraft, four years after launching from Cape Canaveral, at last made contact with the asteroid Bennu and with a quick grab of its robotic arm managed to scoop up a clawful of rocks and pebbles. Only Japan had ever sampled an asteroid before, when its Hayabusa2 spacecraft visited asteroid Ryugu in 2018.
Before the “touch and go” event, there was a chance OSIRIS-REx might have to try a second or even third time to get a good sample. The result was better than expected. On its first try, the probe collected about 400 grams, or 14.1 ounces, of material, surpassing the 60 grams hoped for.
But images revealed the overflowing sample had jammed the lid of the canister open and was letting some leak out, NASA officials disclosed. So instead of sealing the canister next week, NASA planned to start the several-day process Tuesday so no more can escape. The accelerated timeline means NASA will have to skip some tests, meaning the team won’t fully know how big of a sample it got until it arrives on Earth.
“We were almost a victim of our own success here,” said Dante Lauretta, the principal investigator for the mission at the University of Arizona, during a news conference. “I think we’re going to have to wait till we get home to know precisely how much we have, and that, as you can imagine, that’s hard."
It’ll be hard for Campins and Donaldson Hanna, who for years have worked behind the scenes to ready OSIRIS-REx for the moment it would meet Bennu.
Campins, who came to UCF in 2002, helped analyze data and images taken of Bennu while the spacecraft orbited the asteroid, along with associate professor Yan Fernandez. Donaldson Hanna, while she was at Oxford, worked on testing Bennu-like materials.
Alumni of the Florida Institute of Technology in Melbourne also worked on the mission, including Amy Simon, whose team developed the instrument to pinpoint water and other organic materials within the asteroid, and Christian d’Aubigny, who helped develop the cameras OSIRIS-REx used to photograph Bennu, which to the human eye would only register as void blackness.
Bennu, a spinning asteroid about the size of the Empire State Building, is believed to have originally formed 700 million to 2 billion years ago in the asteroid belt between Mars and Jupiter and then collided with another body and drifted toward Earth.
It was selected as a sample site because it could be made of materials that were present when life first formed on Earth. The sample could help scientists understand how the planet formed with just the right balance of oxygen, water, carbon and other elements humans need to survive.
The technology used to pierce the surface of Bennu could also be used to advance space mining, so astronauts don’t have to lug weighty supplies of oxygen and water with them into space, an expensive carry-on in the commercial space industry, where every pound matters.
“The engineering feats that happened to successfully collect the sample could feed into sampling any surface, whether that’s Mars or the moon, Deimos or Phobos, Mars' moons,” Donaldson Hanna said in an interview. “It certainly opens a wide range of possibilities.”
Added Campins: “The moment [NASA or private companies] can produce those resources for less than it costs to launch, they’re going to have a huge clientele willing to buy their product.”
Successfully gathering an asteroid sample bookends a mission that started in 2016 when United Launch Alliance sent up an Altas V rocket and with it the 4,650-pound OSIRIS-REx spacecraft, built by Lockheed Martin. It took two years to get to Bennu and another two years to orbit and map its surface using super-precise cameras to find a safe place to extract a sample.
But Bennu was full of surprises, Campins and Donaldson Hanna said.
Telescopic imaging from Earth had led scientists to believe the asteroid would be fine and sandy, perfect so OSIRIS-REx’s robotic arm could find a vast, flat landing spot. But after observing Bennu closer, “we quickly realized there was no such area,” said Campins. Instead, the surface was full of boulders, some up to 14 feet that may have originated from another asteroid, Vesta, the brightest known asteroid in the sky.
NASA also discovered the asteroid was active and shooting off particles, another potential hazard for OSIRIS-REx.
“That prompted a very big discussion and decision making because we needed to change the way the spacecraft approached the surface. The surface was too rough, too dangerous to bring down the spacecraft the way we wanted to," Campins said, explaining there’s a chance the spacecraft may have also picked up samples from Vesta.
So with the mission already underway, the team had to change tactics. They installed a new software so that OSIRIS-REx could navigate away from areas too risky to take a sample — much like the navigation software NASA’s recently launched Perseverance rover will use when it arrives on Mars. The 18-minute time delay from Bennu to NASA’s Goddard Space Flight Center in Maryland meant the spacecraft would have to perform the entire process autonomously.
After two rehearsal digs in April and August, finally the spacecraft descended at 10 cm, or about 4 inches, per second to Bennu’s Nightingale crater, on the way passing a menacing boulder nicknamed Mount Doom. Then the spacecraft’s robotic arm dug into Bennu’s surface and fired nitrogen gas, sending up a flurry of snow-like dust and particles.
“We have touchdown! Touchdown declared!” announced the team back at Goddard.
The samples won’t arrive on Earth until September 2023, when they parachute down into the Utah desert to be taken to NASA’s Houston facility.
“I think all of us, especially those of us who work in the lab, we’re certainly really anxious to get the samples back as soon as possible and see what the asteroid is really made of,” Donaldson Hanna said.
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