From NASAcompleted a key part of his mission this week by successfully catching rocks on the surface of potentially dangerous asteroid Bennu, NASA reported on Friday.
The spacecraft traveled over 200 million kilometers and four years to briefly strike Bennu, detonate him with compressed gas, and collect pieces from its surface. The space agency shared the first batch of footage from the daring operation on Wednesday, revealing a delicate but explosive moment between rock and robot.
NASA TV reported on Tuesday that the spacecraft’s robotic sampling arm, known as the Touch-And-Go, or Tagsam, sample acquisition mechanism had landed on Bennu. During the brief contact, he performed what amounts to a cosmic pick-pocketing maneuver. Mission planners expected the total contact time between the arm and the asteroid to be less than 16 seconds. When the preliminary data was released, it showed the contact period was only six seconds, with much of the sample collection occurring only in the first three.
The spacecraft, which operates largely autonomously due to the 18-minute communication delay with mission control on Earth, fired a gas canister through Tagsam that disrupted Bennu’s surface and forced a sample into the collector head of the arm.
Photos taken of the head Thursday showed so many samples had been collected that some larger rocks seemed unable to get inside, wedging a mylar flap meant to seal the partially open container, allowing small pieces of dust and pebbles to escape into space.
“Bennu continues to surprise us with great science and throwing a few curved balls as well,” Thomas Zurbuchen, NASA associate administrator for science, said in a statement. “And while we may need to act faster to put the sample away, that’s not a big deal to have. We are so excited to see what appears to be a plentiful sample that will inspire science for decades beyond this historic moment.
Osiris-Rex was designed to land on a flat, even surface, but Bennu is so rocky that the team couldn’t find any suitable space. Fortunately, Osiris-Rex surpassed its design and was able to sample at a site dubbed Nightingale, which measures only a few parking spaces.
Osiris-Rex marks a rock
As the spacecraft approached and then spent two years orbiting Bennu, it became clear that this little world was different from what scientists expected. The team were hoping to find a number of ideal sandy surfaces for sampling, but it turns out Bennu is a pile of rubble, with rough terrain strewn with boulders.
About 24 hours after the operation, NASA shared the first images of the touchdown operation captured by the spacecraft. The Tagsam snaps into place and its sampling head contacts Bennu’s surface before the explosive nitrogen explosion is triggered. The operation lifts a ton of debris which flies around the acquisition arm. It really is something!
Although the GIF above appears relatively fast, the operation went much more smoothly. The arm was lowered at about 10 centimeters per second, much slower than the walking pace, when it touched the sampling site.
The team’s goal is to collect around 60 grams of dust, dirt and pebbles from Bennu’s surface. He reported on Friday that he believed Osiris-Rex had collected a sufficient sample and moved to start putting it away quickly, skipping a planned sample mass measurement and canceling a brake burn to reduce to the minimum acceleration of the spacecraft.
“We’re working to maintain our own success here, and my job is to safely render as large a Bennu sample as possible,” said Dante Lauretta, Osiris-Rex principal investigator at the University of Arizona.
The mission joins the Japanese Hayabusa andin the annals of asteroid exploration. Hayabusa has sampled and returned a very small piece of material from asteroid Itokawa, and Hayabusa2 is returning a large sample of space rock Ryugu.
Once the sample is stowed away, the team will begin preparations for a long trip back to Earth, with a planned landing in the Utah desert in September 2023.