After two years of waiting for the perfect opportunity, NASA on Tuesday will try to collect a sample from an asteroid for the first time.
A spacecraft known as OSIRIS-REx will attempt to vacuum some space dust off the surface of the asteroid Bennu, which scientists think could hold clues about the beginnings of our solar system. The sample will be brought back to Earth in 2023, says Jason Dworkin, NASA project scientist for the mission.
Bennu is a near-Earth asteroid about the size of the Empire State Building that’s made up of a collection of rocks held together by gravity, Dworkin says. It’s “a leftover piece” from the origin of our solar system.
“It has the same chemicals and minerals that went into forming planets, that went into forming the materials that led to life on Earth or maybe elsewhere,” he says. “And so by looking at these materials in the best laboratories around the world, we can learn the history of life, the history of the solar system.”
The most exciting part of the mission, Dworkin says, is that 75% of the asteroid sample will be archived, so future scientists can use the latest technology to study it.
“Scientists not yet born, using techniques not yet invented, can answer questions not yet asked,” he says. “Things I don't even, I can't even think about, they could look at in 50 years.”
This is the first time NASA has tried to scoop a sample off an asteroid, and it’s a bit tricky, Dworkin says. For starters, getting the spacecraft to stay in Bennu’s orbit is difficult.
“The force of gravity on Bennu is about the same as the force of gravity felt on the International Space Station. So it's not zero, but it's very low,” he says. “And the orbit isn't stable over a long period of time.”
Scientists have been studying Bennu to figure out the size of the rocks on the surface, which from afar looked like pebbles and sand, Dworkin says. But it turns out that Bennu is very rocky and fragile.
“It also means that probably there are no meteorites that could be recovered that are like Bennu,” he says. “And so we had to redesign our maneuvers and our sampling strategy to find a site that was the safest ... that we could sample and was also scientifically exciting.”
NASA eventually decided on a landing site called Nightingale, Dworkin says. As the OSIRIS-REx spacecraft approaches the site, an arm that looks like a “10-foot-long pogo stick” will reach out and grab a sample. Dworkin likens the mechanism to an air filter in an old car.
“It uses basically a vacuum backwards to blow a sample of nitrogen gas, and we can capture anywhere between 2 ounces, up to 4 pounds of regolith, that is rocks and dust from the surface,” he says.
If all goes as planned, the spacecraft will return the sample to Earth on Sept. 24, 2023, Dworkin says.
“The spacecraft will point itself at Earth … [and] eject the sample return canister, which has the sample inside of it,” he says. “The spacecraft will then divert away from Earth, going into orbit around the sun, and the canister will descend to the atmosphere and on a parachute land in the Utah desert just before 9:00 a.m. Mountain Daylight Time on Sunday, Sept. 24, 2023.”
Mark your calendars.
This segment aired on October 20, 2020.