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In a briefing today and press release, the OSIRIS-REx science team announced that they estimate that they have gathered a lot of material from the asteroid Bennu, at least 100s of grams, about twice the minimum of what they hoped to get.
In fact, images of the TAGSAM sample grab equipment suggest that there are some larger rocks lodged in its opening (preventing the flap from closing), and that the small movements they have done to photograph it has caused some of the captured material to escape. The image to the right shows this. You can see floating specks and their shadows (the horizontal streaks) that have escaped. At about 9 o’clock you can see a curve in the contact between a lighter material and blackness to its outside, bending towards the center of the TAGSAM. At other exposures they can clearly see a rock there, distorting the shape and thus preventing the flap from closing properly.
Because of this, they are foregoing the spin maneuver that would have weighed the sample, as well as one engine burst that would have slowed the spacecraft’s movement away from Bennu.
This means they will not know the exact amount captured until the sample gets back to Earth. This is a gamble, but they are confident that they have gotten a lot of material. According to Dante Lauretta, the principal investigator, the sample grab-and-go “got very down” into Bennu, as much as 19 inches. He is also confident that they grabbed more than a 100 grams.
They are therefore going to as quickly as possible store the samples in the Sample Return Capsule for return to Earth, beginning on October 27. They need to do a complex series of steps to make this happen, which is why it cannot happen until then.
One more detail: In their simulations prior to the touch-and-go, they had a range of estimates of how deep the spacecraft would penetrate. According to Lauretta, OSIRIS-REx plunged into Bennu at the softest part of that range, telling them that the asteroid is probably much more loosely packed than expected.
Because they are not doing that last engine burst means that they are moving away from Bennu for good. They will not return to the asteroid. Whether they will be able to get post sample grab images of Nightingale is unknown.
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