NASA samples asteroid for secrets of life
NASA spent mere seconds on a billions-year-old asteroid on Tuesday. If the brief encounter went right, it got rocks and dust to learn more about the origin of life on Earth — and how to protect said life should the asteroid come too close for comfort.
The Bennu asteroid, formed nearly 4.5 billion years ago, is like a time capsule for the solar system’s earliest years. And some scientists believe that when ancient asteroids or comets crashed into the Earth, they may have been carrying water and carbon-based molecules that helped initiate life on our planet.
“The returned samples from OSIRIS-REx are going to be able to help us answer key astrobiology questions, such as how water and organic material were delivered to Earth and the role that those key ingredients have played in the early initiation of life on Earth,” said Lori Glaze, director of NASA’s Planetary Science Division, during a Sept. 24 news conference.
And since Bennu has a 1in-2,700 chance of colliding with the Earth between the years 2175 and 2199, knowing more about its composition could help future generations create a deterrence plan should it be needed.
Those questions, and more, are hoped to be addressed by OSIRIS-REx, the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer mission.
Its spacecraft completed a “touch-and-go” — or TAG — maneuver on Tuesday, hopefully collecting at least 60 grams of material from the surface of Bennu and, potentially, up to almost 4½ pounds. Scientists won’t know the exact amount until additional analysis is completed.
Bennu is about as tall as the Empire State Building. The OSIRIS-REx spacecraft is the size of a 15-passenger van. Nightingale, where the spacecraft landed to collect samples, had an 8-meter safe area targeted by the spacecraft.
“This spot is just the
width of a few parking places, and it’s surrounded by large boulder-like structures the size of small buildings,” Mike Moreau, OSIRISREx deputy project manager at NASA’s Goddard Space Flight Center, said during the news conference.
One of those rocks is “reverently referred to as Mount Doom by members of our team,” Moreau added.
Mount Doom and its brethren were a surprise to the OSIRIS-REx team. Based on information from various telescopes, they launched the spacecraft in 2016 expecting a beach-like environment with sand-size particles. They were shocked upon seeing the first images returned from the spacecraft once it reached Bennu in 2018.
“I knew right away we were in for a challenge,” said Dante Lauretta, the OSIRIS-REx principal investigator at the University of Arizona. “First of all, there is nothing that looks like a beach anywhere on this asteroid.”
They were also surprised to see regular eruptions of particles off the surface of Bennu. However, this would later provide some reassurance: These eruptions provided visual confirmation of particles small enough to be collected by the spacecraft, which can collect fine-grain materials up to 2 centimeters in diameter.
Images of the Nightingale site helped researchers confirm that it’d be a good spot to collect samples.
“We have a team of students here at the University of Arizona that are expert asteroid rock counters,” Lauretta said. “And they counted hundreds and thousands of rocks at the scale of 2 centimeters and smaller, so we knew Nightingale was the place to go.”
The spacecraft had to be refined to make this suddenly more complex approach, Moreau said, including adding a new capability to track features on the asteroid to improve navigation. A hazard map enabled the spacecraft to abort its approach should the spacecraft detect a hazardous item in its landing path. These capabilities were initially planned as backup measures, but they were needed for primary measures.
“There were just no places on Bennu that even came close to what we had designed the system for,” Moreau said.
The OSIRIS-REx spacecraft began its descent toward Bennu Tuesday around 1 p.m. CDT. It slowly moved toward the surface of Bennu over a four-hour period.
Because it takes 18.5 minutes to send signals one way, the OSIRIS-REx spacecraft landed autonomously. Reaching Bennu a little before 5:15 p.m. CDT.
The “tag” portion lasted just a few seconds; the spacecraft fired a pressurized nitrogen bottle to agitate and lift Bennu’s surface material. That was to be caught by the spacecraft, which then backed away from the asteroid.
If the spacecraft didn’t collect enough material from Bennu, there could be a backup mission in January at a different site on Bennu.
But if the collection is sufficient, the sample will be secured for its journey home. NASA said Tuesday night that the spacecraft will begin its return to Earth in March. It’s set to land in
Utah in September 2023.
“It’s going to probably be Christmas in September,” Lauretta said. “The best Christmas present I’ve ever had. These pristine samples from asteroid Bennu that I’ve been dreaming — literally dreaming about — for at that point almost 20 years of my life.”