NASAs Asteroid hunter Osiris Rex NASA completed an important part of its mission on Friday by managing to snag some stones from the surface of the potentially dangerous asteroid Bennu.
The spaceship traveled over 200 million miles and four years to briefly encounter Bennu, blast it with pressurized gas, and collect parts of its surface. The space agency shared the first pictures of the daring operation on Wednesday, revealing a delicate but explosive moment between rock and robot.
When the spacecraft's robotic sampling arm called the Touch-and-Go Sample Acquisition Mechanism (Tagsam) landed on Bennu, he was performing a cosmic pickpocketing maneuver. Mission planners expected a total arm-to-asteroid contact time of less than 16 seconds. When preliminary data were released, it was found that the contact time was only six seconds, with much of the sampling only occurring in the first three.
The spaceship, which works largely autonomously due to the 18-minute communication delay with mission control on Earth, fired a gas canister through Tagsam, which destroyed the surface of Bennu and pressed a sample into the collecting head of the arm.
Photos taken of the head Thursday showed that so much sample was collected that some larger stones did not appear to make it inside. They clamped a mylar flap to partially seal the container and allow some small bits of dust and pebbles to escape back into space.
"Bennu continues to surprise us with great science and also throws a few curveballs," said Thomas Zurbuchen, NASA's associate science administrator, in a statement. "And while we may need to move faster to stow the sample, this isn't a bad problem. We're so excited to see what an abundant sample appears to be that will inspire science for decades beyond this historic moment. "
Osiris-Rex was designed to sit on a flat surface, but Bennu is so rocky that the team couldn't find a suitable spot. Fortunately, Osiris-Rex outperformed its design and was able to conduct its sampling on a site called Nightingale, which is only about the size of some parking lots.
Osiris-Rex marks a boulder
As the spaceship approached and then circled and surveyed Bennu for two years, it became clear that this tiny world is not what scientists expected. The team hoped to find a number of sandy surfaces ideal for sampling, but it turned out Bennu was a heap of rubble with a rough terrain full of boulders.
Around 24 hours after the operation, NASA announced the first images of the touchdown operation captured by the spaceship. The Tagsam moves into position and its sampling head touches Bennu's surface before the explosive burst of nitrogen is fired. The operation throws up a ton of debris flying around the detection arm. It really is something!
Although the above GIF appears relatively quick, the operation went much finer. The arm was lowered at about 10 centimeters per second, much slower than the walking pace when it contacted the sample site.
The team's goal is to collect about 60 grams of dust, dirt, and pebbles from the surface of Bennu. It reported Friday that it believes Osiris-Rex has collected enough sample and moved around to quickly tuck it away, skip a scheduled sample mass measurement, and stop a brake burn to keep the spacecraft's acceleration to a minimum.
"We are working to keep up with our own success and my job is to safely return as large a sample of Bennu as possible," said Dante Lauretta, chief investigator for Osiris-Rex at the University of Arizona.
The mission joins Japan's Hayabusa and Hayabusa-2 missions in the annals of asteroid exploration. Hayabusa has collected and returned a small piece of material from the asteroid Itokawa, and Hayabusa2 is in the process of returning a significant sample of the Ryugu space rock.
Once the sample is stowed away, the team will begin preparations for a long journey back to Earth with a scheduled landing in the Utah desert in September 2023.
