APOD: Tagging Bennu: The Movie (2020 Nov 03)

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APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by APOD Robot » Tue Nov 03, 2020 5:05 am

[img]https://apod.nasa.gov/apod/calendar/S_201103.jpg[/img] Tagging Bennu: The Movie

Explanation: This is what it looks like to punch an asteroid. Last month, NASA's robotic spacecraft OSIRIS-REx descended toward, thumped into, and then quickly moved away from the small near-Earth asteroid 101955 Bennu. The featured video depicts the Touch-And-Go (TAG) sampling event over a three-hour period. As the movie begins, the automated probe approaches the 500-meter, diamond-shaped, space rock as it rotates noticeably below. About 20 seconds into the video, Nightingale comes into view -- a touchdown area chosen to be relatively flat and devoid of large boulders that could damage the spaceship. At 34 seconds, the shadow of OSIRIS-REx's sampling arm suddenly comes into view, while very soon thereafter rocks and gravel fly from the arm's abrupt hard impact. The wily spacecraft was able to capture and successfully stow some of Bennu's ejecta for return to Earth for a detailed analysis. This long return is scheduled to start in 2021 March with arrival back on Earth in 2023 September. If the return sample does successfully reach Earth, it will be scrutinized for organic compounds that might have seeded a young Earth, rare or unusual elements and minerals, and clues about the early history of our Solar System.

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by rj rl » Tue Nov 03, 2020 5:40 am

My visual cortex struggles to process the last few seconds 🤔

Curtis

Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by Curtis » Tue Nov 03, 2020 3:08 pm

Has consideration been given to the possibility that the sample being returned to earth by OSIRIS-REx contains a hazardous organic or inorganic compound that could create a wide spread pandemic on the earth?

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by Chris Peterson » Tue Nov 03, 2020 3:26 pm

Curtis wrote:
Tue Nov 03, 2020 3:08 pm
Has consideration been given to the possibility that the sample being returned to earth by OSIRIS-REx contains a hazardous organic or inorganic compound that could create a wide spread pandemic on the earth?
No compound can create a pandemic. And anything living in such an environment (which is extraordinarily unlikely) would necessarily be so different from life on Earth that pathogenicity (or even the ability to survive or reproduce) would be equally unlikely.
Chris

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NCTom

Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by NCTom » Tue Nov 03, 2020 4:34 pm

A 500 meter pile of gravel can create enough gravity to hold its pebbles together! Do we have any idea what property of matter creates gravity? My physics classes never discussed that question.

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by Chris Peterson » Tue Nov 03, 2020 4:54 pm

NCTom wrote:
Tue Nov 03, 2020 4:34 pm
A 500 meter pile of gravel can create enough gravity to hold its pebbles together! Do we have any idea what property of matter creates gravity? My physics classes never discussed that question.
To the extent that we want to call mass a property of matter, that is what is responsible for the force of gravity (indirectly, in that mass changes the shape of spacetime, which is basically what gravity is).
Chris

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by johnnydeep » Tue Nov 03, 2020 5:57 pm

Chris Peterson wrote:
Tue Nov 03, 2020 4:54 pm
NCTom wrote:
Tue Nov 03, 2020 4:34 pm
A 500 meter pile of gravel can create enough gravity to hold its pebbles together! Do we have any idea what property of matter creates gravity? My physics classes never discussed that question.
To the extent that we want to call mass a property of matter, that is what is responsible for the force of gravity (indirectly, in that mass changes the shape of spacetime, which is basically what gravity is).
And as for what causes "mass", we have the mysterious Higgs boson and the Higgs field. From https://simple.wikipedia.org/wiki/Higgs_field:
The Higgs field is a field of energy that is thought to exist in every region of the universe. The field is accompanied by a fundamental particle known as the Higgs boson, which is used by the field to continuously interact with other particles, such as the electron. Particles that interact with the field are "given" mass and, in a similar fashion to an object passing through a treacle (or molasses), will become slower as they pass through it. The result of a particle "gaining" mass from the field is the prevention of its ability to travel at the speed of light.

Mass itself is not generated by the Higgs field; the act of creating matter or energy from nothing would violate the laws of conservation. Mass is, however, gained by particles via their Higgs field interactions with the Higgs Boson. Higgs bosons contain the relative mass in the form of energy and once the field has endowed a formerly massless particle, the particle in question will slow down as it has now become "heavy".

If the Higgs field did not exist, particles would not have the mass required to attract one another, and would float around freely at light speed. Also, gravity would not exist because mass would not be there to attract other mass.

Giving mass to an object is referred to as the Higgs effect. This effect will transfer mass or energy to any particle that passes through it. Light that passes through it gains energy, not mass, because its wave form doesn't have mass, while its particle form constantly travels at light speed.
"To Boldly Go......Beyond The Fields We Know."

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by neufer » Tue Nov 03, 2020 8:36 pm

https://en.wikipedia.org/wiki/OSIRIS-REx#Sample_acquisition wrote:
<<Rehearsals were performed before the sampling event, during which the solar arrays were to be raised into a Y-shaped configuration to minimize the chance of dust accumulation during contact and provide more ground clearance in case the spacecraft tips over (up to 45°) during contact. The descent was very slow to minimize thruster firings prior to contact in order to reduce the likelihood of asteroid surface contamination by unreacted hydrazine propellant. Contact with the surface of Bennu was to be detected using accelerometers, and the impact force was meant to be dissipated by a spring in the TAGSAM arm.

Upon surface contact by the TAGSAM instrument, a burst of nitrogen gas was released, which was meant to blow regolith particles smaller than 2 cm into the sampler head at the end of the robotic arm. A five-second timer limited the collection time to mitigate the chance of a collision. After the timer expired, the back-away maneuver executed a safe departure from the asteroid.

The plan was then for OSIRIS-REx to perform a braking maneuver a few days later to halt the drift away from the asteroid in case it was necessary to return for another sampling attempt. It would then take images of the TAGSAM head to verify a sample had been acquired. If a sample was acquired, the spacecraft would rotate about the short axis of the sample arm to determine sample mass by measuring moment of inertia and determine if it was in excess of the required 60 g.

Both the braking and rotation maneuvers were canceled as images of the sample container clearly showed a large excess of material was collected, a portion of which was able to escape through the container's seal due to some material jamming the mechanism open. The collected material was scheduled for immediate storage in the Sample-Return Capsule. On 28 October 2020, the sample collector head was secured in the return capsule. Following the severance of the head from the collector arm, the arm will then be retracted into its launch configuration, and the Sample-Return Capsule lid will be closed and latched preparing to return to Earth.

In addition to the bulk sampling mechanism, contact pads on the end of the sampling head made of tiny stainless steel loops (Velcro) passively collected dust grains smaller than 1 mm.

On 20 October 2020 at 22:13 UTC, OSIRIS-REx successfully touched down on Bennu. NASA confirmed via images taken during sampling that the sampler had made contact. The spacecraft touched down within 92 cm of the target location. After imaging the TAGSAM head, NASA concluded that there are rocks wedged in the mylar flap that is meant to keep the sample in, causing the sample to slowly escape into space. In order to prevent further loss of the sample through the flaps, NASA canceled the previously-planned spinning maneuver to determine the mass of the sample as well as a navigational braking maneuver and decided to stow the sample on 27 October 2020 rather than 2 November 2020 as was originally planned, which was completed successfully. It was seen that the collector head hovering over the SRC after the TAGSAM arm moved it into the proper position for capture and later the collector head secured onto the capture ring in the Sample Return Capsule.

When the head was seated into the Sample-Return Capsule's capture ring on 28 October 2020, the spacecraft performed a "backout check", which commanded the TAGSAM arm to back out of the capsule. This maneuver is designed to tug on the collector head and ensure that the latches – which keep the collector head in place – are well secured. Following the test, the mission team received telemetry confirming that the head is properly secured in the Sample-Return Capsule. Thereafter, on 28 October 2020, two mechanical parts on the TAGSAM arm must first be disconnected – these are the tube that carried the nitrogen gas to the TAGSAM head during sample collection and the TAGSAM arm itself. Over the next several hours, the mission team commanded the spacecraft to cut the tube that stirred up the sample through the TAGSAM head during sample collection, and separate the collector head from the TAGSAM arm. Once the team confirmed these activities were done, it commanded the spacecraft on 28 October 2020, to close and seal the Sample-Return Capsule, the final step of the sample stowage process of Bennu's samples. To seal the SRC, the spacecraft closes the lid and then secures two internal latches. Additionally, on inspecting images, it was observed that a few particles had escaped from the collector head during the stowage procedure, but it was confirmed that no particles would hinder the stowage process, since the team was confident that a plentiful amount of material remains inside of the head, being more than the needed amount,60 g. Now, the sample of Bennu is safely stored and ready for its journey to Earth. Now that the collector head is secure inside the SRC, pieces of the sample will no longer be lost.>>
Art Neuendorffer

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by sillyworm 2 » Tue Nov 03, 2020 9:45 pm

Besides a marble or 2 ,a top or a tiddlywink I wonder what else we will find.

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Re: APOD: Tagging Bennu: The Movie (2020 Nov 03)

Post by neufer » Tue Nov 03, 2020 11:19 pm

sillyworm 2 wrote:
Tue Nov 03, 2020 9:45 pm

Besides a marble or 2 ,a top or a tiddlywink I wonder what else we will find.
  • With an escape velocity of just ~17 cm/s
    there probably won't be any "winks"
    although there might be a "squidger" or two.
https://en.wikipedia.org/wiki/Tiddlywinks wrote:
<<Tiddlywinks is a game played on a flat felt mat with sets of small discs called "winks", a pot, which is the target, and a collection of squidgers, which are also discs. Players use a "squidger" to shoot a wink into flight by flicking the squidger across the top of a wink and then over its edge, thereby propelling it into the air. The offensive objective of the game is to score points by sending your own winks into the pot. The defensive objective of the game is to prevent your opponents from potting their winks by "squopping" them: shooting your own winks to land on top of your opponents' winks. As part of strategic gameplay, players often attempt to squop their opponents' winks and develop, maintain and break up large piles of winks.>>
Art Neuendorffer