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Asteroid approach, Science operations begin!
Marcin600
post Jun 9 2020, 08:43 PM
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Today, June 9, a very interesting article appeared in Nature Communications, regarding the issues we recently discussed in this forum thread:

Molaro et al. "In situ evidence of thermally induced rock breakdown on Bennu's surface" (pdf with open access)

It has been summarized on the OSIRIS-REx website: "NASA's OSIRIS-REx Discovers Sunlight Can Crack Rocks on Asteroid Bennu"


Few quotes:

“...This is the first time evidence for this process, called thermal fracturing, has been definitively observed on an object without an atmosphere...”

„ ...[OSIRIS-REx] found evidence of exfoliation, where thermal fracturing likely caused small, thin layers (1 – 10 centimeters) to flake off of boulder surfaces. The spacecraft also produced images of cracks running through boulders in a north-south direction, along the line of stress that would be produced by thermal fracturing on Bennu...”

„...Meteoroid impacts do occur on Bennu and can certainly crack rocks, but they would not cause the even erosion of layers from boulder surfaces that were seen. Also, there’s no sign of impact craters where the exfoliation is occurring...”

“...We don’t have good constraints yet on breakdown rates from thermal fracturing, but we can get them now that we can actually observe it for the first time in situ,” said OSIRIS-REx project scientist Jason Dworkin of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Laboratory measurements on the properties of the samples returned by the spacecraft in 2023 will help us learn more about how this process works...”
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Holder of the Tw...
post Jun 17 2020, 01:49 PM
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NASA has released a mosaic picture of the prime landing site Nightingale.

Here is a LINK to the news release which in turn will provide a link to picture selection.

The full resolution mosaic is 345 PolyCam images stitched together, at a resolution of 4mm, is a 152 MB download and is 14371 X 14488 in size.
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Marcin600
post Jun 19 2020, 05:08 PM
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Another amazingly flat boulder on Bennu, close to Osprey - taken by OSIRIS-REx PolyCam on May 26, from 0.3 km
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