NASA secures sample of asteroid Bennu to send home to Earth
NASAscompleted an important part of his mission last week by managing to snatch rocks from the surface of the potentially dangerous space rock Bennu. The sample was so abundant that it ended up in space and triggered an early stowage maneuver that the mission team reported Thursday was successful.
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. On October 21, the space agency shared the first pictures of the daring operation, 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 on October 22nd showed that so much specimen was collected that some larger stones did not appear to make it inside. They clamped a mylar flap that was supposed to partially open the container, leaving a few small dust particles and pebbles to escape back into space.
The sample stowage was originally scheduled for November 2nd, but NASA has instead postponed the multi-day process to Tuesday.
“The abundance of material we have collected from Bennu made it possible to expedite our stowage decision,” said Dante Lauretta, OSIRIS-REx investigator at the University of Arizona, in a statement.
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 different from 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 Oct. 23 that it believes Osiris-Rex has collected enough sample and moved around to quickly stow it away, skip a scheduled measurement of the sample mass, and stop a brake burn to keep the spacecraft’s acceleration to a minimum to restrict.
“We are working to keep up with our own success here and my job is to safely return as large a sample of Bennu as possible,” said Lauretta.
While the process of collecting the sample was carried out autonomously by the spacecraft, stowing the sample is a much slower, step-by-step process in which mission control sends commands and evaluates the results before proceeding to the next step.
The mission joins Japan’s Hayabusa andin 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.
With the sample now stowed on Osiris-Rex, the team will begin preparations for a long journey back to Earth and land in the Utah desert in September 2023.