NASA’s OSIRIS-Rex spacecraft will “mark” the asteroid Bennu on Tuesday (October 20) and collect a sample to return to Earth.
OSIRIS-REx is NASA’s first asteroid sampling spacecraft. The Touch and Movement (TAG) sampling attempt involves a series of maneuvers that will bring the spacecraft to the asteroid’s surface. The location chosen for the touchdown is called Nightingale, which is a rocky area 16 feet (16 meters) in diameter and is located in the northern hemisphere of Bennu, according to NASA.
“We have never done this before,” said NASA̵
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To achieve this, the spacecraft has been orbiting Bennu since 2018 and studying the asteroid in great detail, looking for the optimal landing site – a place that is large enough, relatively flat and covered with fine-grained materials.
However, finding this type of area was a challenge, which led to a number of additional close flights and observations to select a suitable sampling site. The OSIRIS-REx team looked at other potential locations such as Osprey, Kingfisher and Sandpiper before choosing Nightingale, which has the largest amount of unobstructed fine-grained material, according to NASA.
How TAG will work
NASA’s OSIRIS-REx spacecraft will perform three separate maneuvers to reach the asteroid’s surface. The first step is called a checkpoint burn, during which the spacecraft will launch its pushers to adjust its position relative to the Nightingale test site. When OSIRIS-REx reaches an approximate height of 177 feet (54 m), another maneuver called burning a match point will slow down the spacecraft’s descent and direct a path that corresponds to the asteroid’s rotation during contact, according to NASA.
The spacecraft’s robotic sampling arm, called the touch-and-go sampling mechanism (TAGSAM), will then make contact with Bennu’s surface in less than 16 seconds before returning to orbit. Upon contact with the asteroid, one of the three pressurized nitrogen containers will fire, stirring sample dust and small rocks, which can then be captured in the collector head of the hand and stored to return to Earth.
It will take about four hours to get to the surface of Bennu. The spacecraft will use natural tracking (NFT) to recognize landmarks during its descent and update its position, if necessary, to navigate around large rocks and ensure a safe landing in relatively clean space, explained David Lorenz. campaign manager in TAG video.
“There are a few things that can go wrong, and we also need to be prepared that we will not succeed on our first attempt at Nightingale,” said Mike Moreau, deputy project manager for OSIRIS-REx. “
In the event that the first TAG attempt is unsuccessful, the spacecraft will be equipped with spare pressure nitrogen containers, which will allow additional sampling attempts. The team hopes to collect 2 ounces. (60 grams) of fine-grained material from the asteroid’s surface, which will be the largest sample returned from space since the Apollo program, according to NASA.
The OSIRIS-REx team also studied Nightingale to identify areas within the test site that could potentially damage the spacecraft. A hazard map of the site has been developed and programmed into the spacecraft’s navigation system, so that if the NFT system detects a dangerous landmark, the spacecraft will retreat autonomously from the asteroid. This will allow the mission to retry sampling at a future date, according to the video.
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After taking its sample, OSIRIS-REx will fire its pushers to retreat from Bennu. If everything goes according to plan during the collection, the team will check the sample by taking a picture of the TAGSAM head to see if it contains surface material. A rotation maneuver will also be performed on Saturday (October 24th) to measure the mass of the sample and provide at least 2 ounces. (60 grams) of material has been collected and could be stored for return to Earth in 2023. However, if not enough sample is collected, the spacecraft will be able to make two more experiments, according to the video.
“It’s really exciting to know that we will finally be able to touch the asteroid’s surface and collect a sample to get back to Earth,” Castro said.
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