The spacecraft’s sampling arm, called the Touch-And-Go Sample Acquisition Mechanism, over the target sample site during a dress rehearsal in April.
NASA
NASA’s asteroid-chaser, Osiris-Rex, completed a brief and historic landing on the potentially hazardous asteroid Bennu, over 200 million miles away from Earth on Tuesday. On Wednesday, the space agency revealed the first batch of images from the daring operation, revealing a delicate-yet-explosive moment between rock and robot.
Osiris-Rex traveled all that way to perform a short touch-and-go maneuver. Its major goal is to collect a sample from the asteroid’s surface and transport it back to Earth for study.
On Tuesday, NASA TV reported the spacecraft’s robotic sampling arm, named Touch-And-Go Sample Acquisition Mechanism, or Tagsam, did touch down on Bennu. During the brief contact, it performed what amounts to a cosmic pickpocketing maneuver. Mission planners expected that the total time of contact between the arm and asteroid would be less than 16 seconds. When preliminary data was released on Wednesday, it showed that the period of contact was just six seconds, with much of the sample collection happening in only the first three seconds.
The spacecraft, which operates largely autonomously due to the 18-minute communications delay with mission control on Earth, fired a canister of gas through Tagsam that disrupted the surface of Bennu and should have enabled a sample to make its way up into the arm’s collector head.
Osiris-Rex was designed to touch down on a flat, even surface, but Bennu is so rocky the team found no suitable space. Fortunately, Osiris-Rex outperformed its design and was able to perform its sampling on a site dubbed Nightingale, which is only about as big as a few parking spaces.
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NASA successfully lands Osiris-Rex spacecraft on an asteroid…
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Osiris-Rex tags a boulder
Around 24 hours after the operation, NASA shared the first images of the touchdown operation captured by the spacecraft. The Tagsam moves into position and its sampling head makes contact with Bennu’s surface before the explosive burst of nitrogen is fired. The operation kicks up a ton of debris that flies around the acquisition arm. It’s really something!
Touchdown!
NASA
Although the above GIF appears relatively fast, the operation proceeded much more delicately. The arm was lowered at around 10 centimeters per second, much slower than 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. To determine if that goal has been met, Osiris-Rex has maneuvered to a safe distance and will now move its arm into position to take photos of the collector head and weigh how much mass lies within.
There’s no guarantee Osiris-Rex has collected a significant sample. As the spacecraft approached and then spent two years orbiting and surveying Bennu, it became clear this tiny world is different from what scientists expected. The team hoped to find a number of sandy surfaces ideal for sampling, but it turns out Bennu is a rubble pile, with a rugged terrain strewn with boulders.
The Osiris-Rex team celebrates at the moment of touchdown.
NASA TV
More measurements will be required to confirm material is within the sampling head, but if Osiris-Rex has succeeded, it will join Japan’s Hayabusa and Hayabusa-2 missions in the annals of asteroid exploration. Hayabusa sampled and returned a tiny bit of material from asteroid Itokawa, and Hayabusa2 is in the process of returning a significant sample of space rock Ryugu.
Should the mission gather up a sample, it will begin a long journey back to Earth, with a planned landing in the Utah desert in September 2023.
Updated Oct. 21: To clarify the amount of time Osiris-Rex spent on Bennu.
