Asteroid approach, Science operations begin! |
Asteroid approach, Science operations begin! |
Oct 22 2020, 06:33 PM
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#196
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Newbie Group: Members Posts: 2 Joined: 7-July 15 Member No.: 7562 |
Good spray of material with the nitrogen blast. This is what they were looking for to indicate a good potential for a sample https://youtu.be/LJBv4reH9IU Thank you for making the retimed video. Really like it touchdown on the rocky equivalent of styrofoam or cheese puff. The rocks are "just" hold" together. Nitrogen pressure might have been overkill. Hope they got a good sample. |
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Oct 22 2020, 06:45 PM
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#197
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Wow, the expectation was that these rocks would be unlike anything in our meteorite collections because they couldn't survive entering the Earth's atmosphere. That turns out to be a profound understatement. These samples really could represent something we've never seen before.
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Oct 22 2020, 08:28 PM
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#198
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Member Group: Members Posts: 404 Joined: 5-January 10 Member No.: 5161 |
I'm having a little trouble understanding the dark background, starting the instant the gas is released and debris starts flying. Is the debris cloud so dense that it instantaneously blocks almost all sunlight from reaching the ground below? I guess that's the case, but it seems surprising. And then why is there such a well-defined edge to the shadow in the final frames? Why does the debris cloud have sharp enough edge to cast a shadow like that? John I was wondering exactly the same thing. Very perplexing. Neo56's excellent sequence (click here for it) makes me think it's a crater and not a shadow, but then again, the edge of the "crater" seems to shift, like it's a dust shadow. Or perhaps the edge of the crater is settling and shifting slowly. Considering that the astroid is active, popping up little parts of itself that slowly settle back on the surface, played out over billions of years the surface might be somewhat like a children's ball bit with light plastic balls to easily sink into. |
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Oct 22 2020, 11:28 PM
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#199
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
It reacts like a frozen clump of sand or gravel.
Not unlike the lumps you get in a salt shaker near the ocean - Random video- https://www.facebook.com/watch/?v=10155535292172786 |
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Oct 23 2020, 03:22 PM
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#200
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Member Group: Members Posts: 540 Joined: 17-November 05 From: Oklahoma Member No.: 557 |
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Oct 23 2020, 04:33 PM
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#201
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Member Group: Members Posts: 699 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
Neo56's excellent sequence (click here for it) makes me think it's a crater and not a shadow, but then again, the edge of the "crater" seems to shift, like it's a dust shadow. Or perhaps the edge of the crater is settling and shifting slowly. Considering that the astroid is active, popping up little parts of itself that slowly settle back on the surface, played out over billions of years the surface might be somewhat like a children's ball bit with light plastic balls to easily sink into. Thanks- Neo56's sequence makes things clearer. It does look like the gas release rapidly excavated a surprisingly large crater, which is responsible for most of the shadowing. In that sequence the crater shape appears to be relatively stable (because the shadow edge is relatively stable) but the stuff inside it is still churning around in the microgravity. I hope there are frames later in the sequence that we haven't seen yet, which show the view from a greater distance. Hopefully the surface put up enough resistance to provide the back-pressure necessary to propel material upward into the sample chamber. John |
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Oct 23 2020, 09:20 PM
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#202
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
Is there a minimum weight requirement in the sample to be considered a successful sample return?
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Oct 23 2020, 09:28 PM
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#203
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Senior Member Group: Members Posts: 2511 Joined: 13-September 05 Member No.: 497 |
Is there a minimum weight requirement in the sample to be considered a successful sample return? Yes, 60 grams. https://www.asteroidmission.org/?latest-new...-asteroid-bennu -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Oct 23 2020, 09:58 PM
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#204
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Newbie Group: Members Posts: 8 Joined: 6-August 11 From: Bariloche, Argentina Member No.: 6102 |
So much sample was collected that some of it is actually slowly escaping the sampling head. Sample mass measuremente has been cancelled to protect the sample, and they will store it as it is.
https://twitter.com/OSIRISREx/status/1319750746741612546 -------------------- Guillermo Abramson
Leés español? Visitá mi blog! |
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Oct 23 2020, 10:54 PM
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#205
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Member Group: Members Posts: 435 Joined: 14-December 15 Member No.: 7860 |
"...Analysis by the OSIRIS-REx team suggests that bits of material are passing through small gaps where the head’s mylar flap is slightly wedged open. The mylar flap (the black bulge on the left inside the ring) is designed to keep the collected material locked inside, and these unsealed areas appear to be caused by larger rocks that didn’t fully pass through the flap..."
"All data so far suggest that the collector head is holding much more than 2 ounces of regolith" (here) I wonder if these escaping pieces of rocks will not cause a problem with the tight closure of the sampler head in the return capsule |
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Oct 23 2020, 11:09 PM
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#206
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Senior Member Group: Members Posts: 2082 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Wow, it is literally chock-full of sample! A nice problem to have....I almost expected that given the enormous cloud, but good to know for sure!
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Oct 23 2020, 11:14 PM
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#207
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Member Group: Members Posts: 406 Joined: 18-September 17 Member No.: 8250 |
"All data so far suggest that the collector head is holding much more than 2 ounces of regolith" (from here) From the audio teleconference:
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Oct 23 2020, 11:36 PM
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#208
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Member Group: Members Posts: 435 Joined: 14-December 15 Member No.: 7860 |
"...Continued to move forward for an additional 3 seconds after gas release while backoff thrusters were firing before moving away..."
Could the gases from the backoff thrusters "contaminate" the samples? |
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Oct 23 2020, 11:55 PM
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#209
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Member Group: Members Posts: 444 Joined: 1-July 05 From: New York City Member No.: 424 |
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Oct 23 2020, 11:56 PM
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#210
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Senior Member Group: Members Posts: 2511 Joined: 13-September 05 Member No.: 497 |
One thing that surprised me was Dante talking about "dust loading" (I think he said) on Navcam and SamCam. I wonder how dirty the nadir panel of the spacecraft is now?
-------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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