Washington — NASA’s OSIRIS-REx spacecraft has secured the material collected from the asteroid Bennu into the sample return capsule. After the images showed that the material had leaked into space, the mission accelerated.
At a briefing on October 29, project officials said that they had installed a sample collection device called a “ready to use” sample collection device (TAGSAM) into the cabin of the spacecraft. The robotic arm moves the TAGSAM head to the position inside the capsule, and then seals it off.
TAGSAM’s head touched the surface of the asteroid Bennu for a few seconds on October 20, and it appeared to have captured a lot of material. However, officials said on October 23 that TAGSAM collected so much material, and the Mylar flap, which was designed to seal the material in place, was wedged away by a few large rocks, causing some material to leak out from spaceflight. It can be seen in the image of the device.
Then, NASA decided to speed up the process of loading the TAGSAM head into the capsule, which would return the material to Earth without the need to perform operations to weigh the sample. The controller spent approximately 36 hours on October 26 and 27, using the robotic arm to move the TAGSAM head to the position where the sample returned to the capsule, and confirm that it was locked in place, and then sealed the capsule.
“Storage is a stressful period of operations. Our flight team works around the clock, much shorter than we thought.”
The stored procedure was originally scheduled to take place in early November, so moving it up means that you can ensure the time of other users on the Deep Space Network (DSN). Lori Glaze, director of NASA’s Planetary Science Division, said: “At the last minute, there are many tasks that need to be renegotiated.”
Dante Lauretta, the lead researcher on the mission at the University of Arizona, said he was confident that despite the material leakage, when the TAGSAM head was sealed in the capsule, there was still a lot of material in the head. He said: “We continue to analyze the images and do estimate that tens of grams of samples may have been leaked during the entire operation.”
The accelerated stowage process means that the project skipped the slow rotation of the spacecraft, thereby measuring the change in the moment of inertia before self-sampling, and estimated the mass of matter collected from the asteroid accordingly. This action may cause more material to escape.
However, Laureta said he is confident that the spacecraft retains much more material than its target of 60 grams. He said the image inside the head showed at least 400 grams of substance. He added that these images only cover 17% of the TAGSAM head. He said: “We can see a large number of samples everywhere we can see in TAGSAM.” “We may be more than one kilogram of material.”
There may be other ways to estimate the quality of the material, for example, the way the robot moves during the loading process. Flender said: “We absolutely hope to have an estimated sample mass before 2023,” when the spacecraft returns to Earth.
Scientists have been analyzing the images taken during and after sampling to better understand the surface. He said that the material leaked from TAGSAM is “flaky” in appearance. He said: “It looks like you have thrown a box of corn flakes in space. They are flying around, kind of moving randomly.”
The surface of Bennu itself is very weak. The TAGSAM head will drop into a depth of half a meter when it is briefly touched. “Basically, there is almost no force between the grains to bind them together. They are not interdependent in any way,” Lauretta said. If an astronaut steps on the surface, “she will sink to the knees or deeper, depending on how loose the soil is, until you hit a larger boulder or some kind of bedrock.”
However, a deep drop may allow OSIRIS-REx to collect material from below the surface. He said that this material should be protected from direct sunlight and is rich in volatiles.
After securing the materials collected by Bennu in the sample return module, the mission now focuses on returning these samples to Earth. Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center, said that the maneuver window for the spacecraft to leave near Bennu will open in early March 2021. The departure maneuver will return the spacecraft to Earth in September 2023.