Scientists say touching and landing by NASA’s Osiris Rex spacecraft on an asteroid last month revealed new insights into the bulk structure of rocks that may cover the surfaces of many small planetary bodies – material more like a ball pit in the field than solid. Foundation stone.

The structure of the asteroid’s outer layer is evident in images taken by the OSIRIS-REx spacecraft as it descended into the airless world more than 200 million miles (330 million km) from Earth on October 20.

The next day, NASA released images from a narrow-angle camera aimed at the robotic arm of the spacecraft’s 11 feet (3.4 meters) long. A dinner plate-sized sampling device at the end of the arm released a bottle of compressed nitrogen gas when the spacecraft touched the surface of asteroid Bennu, a small planetary object about a third of a mile in diameter.

Discharge of nitrogen gas forced asteroid samples into the collection chamber. After six seconds on the surface of the asteroid, Osiris Rex launched thrusts away from Bennu.

Scientists later received close-up pictures of the sample collection head, showing that it was packed with material captured from the asteroid’s surface. Some asteroid particles were visible as they were escaping from the collection room, prompting managers to order the spacecraft to store the sample head inside the capsule back to Earth sooner than expected, thus minimizing sample loss.

The sampling device inside the return capsule of the OSIRIS-REx spacecraft was closed on 28 October.

Late last week, officials released another series of photos taken while the spacecraft was touching and landing. Captured with a wide-angle navigation camera in OSIRIS-REx.

According to the OSIRIS-REx science team, the images were captured with a navigation camera – or NavCam – over a period of approximately three hours. Officials said the sequence begins about an hour after Osiris Rex performs an exit maneuver to begin the descent, and ends about two minutes after the spacecraft combusts.

A large number of maneuvers or rotations can be seen in the middle of the image sequence as OSIRIS-REx directs the sampling arm towards the target sampling site on the asteroid Bennu, an area called “Nightingale”.

“As the spacecraft approaches the position of Nightingale, the shadow of the sampling arm appears at the bottom of the frame. Soon after, the sampling head impacts the Nightingale position (just outside the camera’s field of view to the top right) and releases the nitrogen gas bottle, which crowds a great deal From the sample site material, “the OSIRIS-REx team wrote in a description from the NavCam images.

“After several seconds, the spacecraft performs a backburn and a shadow of the sampling arm appears on the turbulent surface material. The team is continuing to investigate why the very dark areas appear in the upper and middle parts of the frame.” “The upper region could be the edge of the drop caused by the sampling arm, or the strong shadow caused by material raised from the surface, or a combination of the two.

“Likewise, the middle dark region that first appears in the lower left portion of the image could be a drop from one of the spacecraft propulsion engines as it launched, a shadow from elevated matter, or a combination of both.”

Lockheed Martin’s OSIRIS-REx spacecraft relied on black-and-white navigation camera images to independently orient itself to a safe landing area at Benno. Navigation algorithms compared the camera images to a map pre-loaded in the spacecraft’s computer, helping OSIRIS-REx determine its position in relation to the asteroid.

With the specimen locked in the return capsule, Osiris Rex is set to leave the vicinity of the asteroid Benno next year to begin its return journey to Earth. The spacecraft will launch a re-entry capsule to re-enter Earth’s atmosphere and land at Test and Training Field in Utah on September 24, 2023.

The NASA Asset, Spectral Interpretation, Resource Identification, Security, and Regolith Explorer Mission’s $ 1 billion mission were launched on September 8, 2016, from Cape Canaveral aboard the United Launch Alliance Atlas 5 rocket. OSIRIS-REx’s primary goal is to return samples from the asteroid. To Earth for detailed analysis by scientists, who hope to uncover clues about the origins of the solar system.

The mission requirement was for Osiris Rex to collect at least 60 grams, or 2.1 ounces, of the asteroid material. Scientists said before October 20, the spacecraft could collect much more, and evidence suggests that it will likely catch more than 2.2 pounds, or 1 kilogram, of asteroid samples, according to Dante Loretta, the mission’s lead investigator from the university. Arizona State.

Data from the short landing on the asteroid indicates that the spacecraft’s robotic arm sank up to 19 inches (48 cm) into Benno’s soft surface.

While the scientific payoff for the mission will wait until the asteroid samples return to Earth, Loretta said Thursday that scientists are already learning about the physical properties of Pino.

The spacecraft detected small particles flying off Benno shortly after it reached the asteroid in December 2018. These particles look similar to crustacean material that leaked from TAGSAM’s head.

“It’s like a box of cornflakes in space,” said Loretta. “And they’re flapping in some kind of random movement. They come from the head of TAGSAM mostly, but they’re bumping into each other. It’s spinning and going down. We can solve a lot of it.”

“So it’s a great imaging calibration dataset for understanding the particle ejection events and particle trajectories that we observed throughout the entire encounter with the asteroid,” said Loretta. “Even though my heart was broken due to missing a sample, it turned out to be a great science experiment.”

OSIRIS-REx contact with the asteroid’s surface on October 20 also provided a rich data set, indicating that the outer layer of asteroid soil and low-density rocks lacked much cohesion. The robotic arm of the spacecraft touched the asteroid as Osiris Rex approached at 0.2 miles per hour, or 10 centimeters per second, about a tenth of the speed of the usual walking rhythm.

“When TAGSAM’s head touched the regolith, it flew away like a liquid,” said Loretta. “I think this would happen to an astronaut if she tried to walk on the surface of the asteroid. She would sink down her knees or deeper – depending on how loose the soil is – until she collides with a larger rock or some kind of fundamental rock.”

He said the “ground truth” data collected by Osiris Rex will help scientists re-examine asteroid geology models.

“It’s amazing that there was so little resistance to the spacecraft from the surface of the asteroid,” said Loretta. “Basically, it’s like a ball pit on a kid’s playground. You kind of jump into it as you dive in.

“Fortunately, we had those rear thrusters to reverse the direction of motion, or we might have flown all the way through the asteroid,” Loretta joked.

New measurements of the asteroid density from OSIRIS-REx will help scientists improve assessments of the hazards that Bennu may pose to Earth. Scientists have calculated a probability of 1 in 2,700 that Bennu might hit Earth in the late 21st century.

A large portion of an asteroid may burn out in Earth’s atmosphere due to its porosity.

“Thermal analysis indicates that a lot of the materials on Benno’s surface – especially the large, black rocks that make up one of the main components of the surface – appear to have physical properties that will not survive their passage through the atmosphere intact,” Loretta said. . “It’ll crumble, and you’ll lose a lot of material.”

This means that the original samples collected from Bennu do not resemble any meteorites or asteroid fragments that fell to the ground and reached the surface intact.

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