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Scientists say last month the touch and landing of NASA’s OSIRIS-REx spacecraft on the asteroid revealed new insights into the structure of loose rocks that can cover the surfaces of many small planetary bodies, a material that is more similar. to a pit of balls on the field than to a solid bedrock.
The structure of the asteroid’s outermost layer is evident from images captured by the OSIRIS-REx spacecraft, which plunged into the airless world more than 200 million miles (330 million kilometers) from Earth on October 20.
The next day, NASA released images of a narrow-angle camera aimed at a robotic arm of a 3.4 meter long spacecraft. When the spacecraft touched the surface of the asteroid Bennu, a small planetary body about a third of a mile in diameter, a sampling device fired a bottle of compressed nitrogen at the end of its arm at dinner.
The nitrogen gas discharge helped push the asteroid samples into the collection chamber. After six seconds on the surface of the asteroid, OSIRIS-REx repelled the jets from Bennu.
The scientists later received detailed images of the sampling head, which showed it was loaded with material collected from the asteroid’s surface. Some asteroid particles were visible leaking out of the collection chamber, leading those responsible to order the probe to place the sample head in its case back to Earth earlier than expected, minimizing sample loss.
The sampling device was sealed in the OSIRIS-REx probe return capsule on October 28.
At the end of last week, officials released another series of images taken during the spacecraft’s landing and landing. These were captured by a wide angle navigation camera on OSIRIS-REx.
According to the OSIRIS-REx science team, images from the navigation camera – or NavCam – were captured in about three hours. The sequence begins about an hour after OSIRIS-REx performs an orbital departure maneuver to begin descent and ends about two minutes after the probe burned out, officials said.
The turn or maneuver is visible in the middle of the image sequence as OSIRIS-REx directs its sampling arm towards the sampling target on the asteroid Bennu, a region called “Nightingale”.
“As the ship approaches Slavik, a shadow of the sampling arm appears at the bottom of the frame.” Shortly thereafter, the sampling head hits the nightingale’s position (just outside the camera’s field of view at the top right) and fires a bottle of nitrogen, which mobilizes a significant amount of sample site material, “the team wrote. NavCam of the OSIRIS-REx team.
“A few seconds later, the pod will burn out and the shadow of the sampling arm will be visible against the disturbed surface material.” The team continues to investigate what caused the extremely dark areas visible in the top and center of the frame, “the team wrote.” The top area may be the edge of the depression formed by the sampling arm, the strong shadow cast from the material floating off the surface, or a combination of these. “
“Likewise, the dark center area that appears first in the lower left corner of the image could be the depression caused by one of the rocket missiles when fired, a shadow caused by lobed material, or a combination of these. “
The OSHIS-REx spacecraft, manufactured by Lockheed Martin, relied on black and white navigation camera images to be guided autonomously into the safe contact zone on Benn. The navigation algorithms compared the camera images to a map preloaded into the spacecraft’s computer, which helped OSIRIS-REx determine its position relative to the asteroid.
With the sample secured in the return capsule, OSIRIS-REx prepares to leave asteroid Benn next year and begin its journey back to Earth. The spacecraft will release a return capsule to re-enter Earth’s atmosphere and land at the Utah Test and Training Camp on September 24, 2023.
The NASA Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer mission was launched on September 8, 2016 from Cape Canaveral aboard the United Launch Alliance Atlas 5. The main objective of OSIRIS-REx is to return asteroid samples to Earth. for detailed analysis by scientists who hope they reveal traces of the origin of the solar system.
The mission’s task was for OSIRIS-REx to collect at least 60 grams of asteroid material. Prior to the touch and landing on October 20, scientists said the probe could have collected much more and evidence suggests it may have captured more than 2.2 pounds or 1 kilogram of asteroid samples, according to Dante Lauretta. chief investigator of the university. Arizona.
Data from a brief tap on the asteroid indicated that the spacecraft’s robotic arm had plunged into Benn’s soft surface at a height of 48 centimeters.
As the mission’s scientific payment awaits the asteroid samples to return to Earth, Lauretta said on Thursday that scientists were already learning Benn’s physical properties.
The spacecraft discovered small particles flying off Benn shortly after arriving at the asteroid in December 2018. These particles look similar to the scaly material that escaped from TAGSAM’s head.
“It looks like a box of cornflakes in space,” Lauretta said. “And they hang around as if by chance.” They usually come from the head of TAGSAM, but they collide with each other. They turn and fall. We can solve many of them.
“So it’s an excellent calibration dataset to better understand the particle ejection events and particle trajectories that we observed during the encounter with the asteroid,” Lauretta said. “Even though my heart is breaking due to the loss of the sample, it turned out to be a pretty good science experiment.”
OSIRIS-REx’s contact with the asteroid’s surface on October 20 also provided a rich body of data, suggesting that the outer soil layer of asteroids and low-density rocks lacked great cohesion. The spacecraft’s robotic arm touched the asteroid as OSIRIS-REx approached at a speed of just 0.2 miles / h or 10 cents per second, which is about one-tenth the speed of a typical walking pace.
“When TAGSAM’s head came into contact with the regolith, it was simply drained like a liquid,” Lauretta said. “And I think it would happen to an astronaut if he tried to walk on the surface of an asteroid.” It would drop knee-deep or deeper, depending on how loose the ground was, until you hit a larger boulder or bed of rock. “
He said “basic truth” data collected by OSIRIS-REx would help scientists rethink geological models of asteroids.
“It is fascinating that there was so little resistance to the probe surface from the asteroid surface,” Lauretta said. “It’s basically like a ball pit in a playground.” You jump in and dive.
“Fortunately, we had these return jets to reverse the direction of movement, otherwise we could have flown through the asteroid,” joked Lauretta.
The new asteroid density measurements from OSIRIS-REx will help scientists improve their assessment of the impact risk Bennu could pose to Earth. Scientists have calculated a 1: 2,700 chance that Bennu could hit Earth at the end of the 21st century.
Much of the asteroid could burn in Earth’s atmosphere due to its porosity.
“Thermal analysis suggests that much of the material on Benn’s surface – especially the large boulders with black humps that are a major part of the surface – appears to have material properties that would not survive an intact passage through the atmosphere,” Lauretta said. “They would crumble and much of the material would be lost.”
This means that the original samples collected by Benn are different from any meteorite or asteroid fragment that fell to Earth and reached an intact surface.
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Follow Stephen Clark on Twitter: @ StephenClark1.
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