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nprev
Now that the 'boop' has been completed (with spectacular success!), we'll move the discussion to here for subsequent mission events. smile.gif
walfy
Boosted the shadows to reveal what I assume are the rocks wedged in the mylar flap. Looks like our little robot gorged like a T-REx!
Click to view attachment

The third image in the sequence was the most over exposed, so the rocks hiding in the shadows are the least grainy when revealed:
Click to view attachment
dsmillman
The audio of the 10/23/2020 teleconference can be accessed for 30 days at:

1-866-373-4996
Tom Tamlyn
Thanks to for that link.

It was a great press conference. Even though Brian's helpful summary covered most of the the major points, it made fascinating listening, with detailed, clear, and fluent presentations and answers from Dante Lauretta and Thomas Zurbuchen, and sharp, business-like questions from well-informed reporters.

The stow operation is currently expected to begin on Tuesday. As Brian mentioned, the mission is seeking substantial extra DSN coverage in order to do something unusual for robotic spacecraft: conduct an operation interactively with "the ground in the loop." The revised stow plan will have a number of check points, at which the operation will pause while images are downloaded and analyzed to determine whether to proceed with the plan or try something different. As a result the stow operation is expected to last three days, instead of several hours as originally planned.

The previously scheduled activity of spinning the spacecraft with the arm extended to obtain a moment of inertia measurement has been cancelled, and Lauretta pretty much ruled out any other possibility for measuring the sample mass (as opposed to estimating the mass from images) prior to landing. However, he did seem to acknowledge that there had not been any occasion to think about a different way such a measurement could be taken during the return trip. I suppose it's possible they might come up with a way to tease some sample mass information out of trajectory telemetry during the return voyage.
JRehling
Looking at the apparent fragility of those "rocks" I wonder what is going to happen during the high g forces during entry. None of it will vanish, but it might lose some of the original structure.
marsbug
It's a nice problem to have in a way... but it's still a problem . Still it sounds like the team have it in hand.
Explorer1
QUOTE (Tom Tamlyn @ Oct 24 2020, 01:55 PM) *
However, he did seem to acknowledge that there had not been any occasion to think about a different way such a measurement could be taken during the return trip. I suppose it's possible they might come up with a way to tease some sample mass information out of trajectory telemetry during the return voyage.

Assuming the mass without the sample (including fuel and subtracting the nitrogen gas used) is known precisely enough, there should be a slight difference in how it 'handles' during maneuvers like the Earth return burn and any TCMs.
dtolman
So they cancelled the spin because visual inspection confirmed an abundance of material?
Marcin600
QUOTE (dtolman @ Oct 25 2020, 12:42 AM) *
So they cancelled the spin because visual inspection confirmed an abundance of material?


"...To preserve the remaining material..."
"...Any movement to the spacecraft and the TAGSAM instrument may lead to further sample loss..."
"...The loss of mass is of concern to me, so I’m strongly encouraging the team to stow this precious sample as quickly as possible - said Dante Lauretta..."
["some of sample particles appeared to be escaping slowly from the TAGSAM head - passing through small gaps where a mylar flap is slightly wedged open by larger rocks"]
(here)

I think that with very gentle and careful moving the TAGSAM head while enclosing it in the return capsule, and doing it without undue delay, the final loss of the collected mass (they collected about 400 g - much more than planned 60 g) will be insignificant. We have to keep our fingers crossed for this
Reed
QUOTE (dsmillman @ Oct 24 2020, 06:30 AM) *
The audio of the 10/23/2020 teleconference can be accessed for 30 days at:

FWIW, also on youtube (starts at ~13 minutes) https://www.youtube.com/watch?v=n274YX4xk_0 - just audio except for showing the gif from the press release for a while
rlorenz
QUOTE (Explorer1 @ Oct 24 2020, 05:56 PM) *
Assuming the mass without the sample (including fuel and subtracting the nitrogen gas used) is known precisely enough, there should be a slight difference in how it 'handles' during maneuvers like the Earth return burn and any TCMs.


In theory, yes (I think I remember reading a scifi story where a stowaway on a spacecraft is discovered this way). But in practice, this is a very small signal to look for (if you want to measure a 400g sample to 10%, as part of a 400kg spacecraft, that's a 0.01% precision)

I think thruster performance is probably not more consistent than 1%, maybe worse.

Measuring spin rates, and changes therein is something that can be done with exquisite precision, but more particularly putting the sample mass out on the TAGSAM arm gives a large moment arm, so the sample mass 'signal' component of the vehicle's moment of inertia. So having a viable retrieval of sample mass from this spin exercise does not mean you can do it with useful precision in a translation manoeuvre....
mcaplinger
QUOTE (rlorenz @ Oct 25 2020, 02:16 PM) *
In theory, yes (I think I remember reading a scifi story where a stowaway on a spacecraft is discovered this way). But in practice, this is a very small signal to look for (if you want to measure a 400g sample to 10%, as part of a 400kg spacecraft, that's a 0.01% precision)... I think thruster performance is probably not more consistent than 1%, maybe worse.

Agreed, I don't think thruster firing is going to tell you anything.

But the other small forces on the spacecraft (e.g., radiation pressure) might be well enough characterized. Time will tell.

The story is of course https://en.wikipedia.org/wiki/The_Cold_Equations
JRehling
Apollo 13 had a bit of a concern regarding sample mass, but it was an issue of many kg, not g:

http://www.collectspace.com/news/news-0416..._souvenirs.html
stevesliva
QUOTE (mcaplinger post Oct 23 2020 @ 06:56 PM Post #210)
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?


Any word on this? I wonder in the context of an extended mission (proposal? idea?).
jccwrt
If Bennu regolith is anywhere near as sticky as lunar regolith, that whole part of the spacecraft is probably filthy from the compressed nitrogen burst.
Explorer1
Expedited stow begins tomorrow. Images will be returned at each step. https://www.nasa.gov/press-release/nasa-s-o...asteroid-sample
Marcin600
An excerpt from Dante Lauretta speech about the dust on the camera - from the quoted audioconference [44:50 - 45:35]:

„...We have seen that there is dust loading on our other optical elements, the navigation camera... and the sam cam which used to document the interaction with the asteroid surface. So we do need to know the state of that camera. And the dust loading isn’t a problem, it just changes the exposure times. I like to think about, you know, when you’re wearing glasses and the glasses are pretty dirty, you don’t really notice it until you take the glasses away and look and clean them, but not as much light as passing through those lenses, so you just need to stare integrate the camera time longer for that activity. So that is one reason and one thing we plan on doing on monday, is checking out the camera. So we’re hoping to begin the stow activities on tuesday...”
HSchirmer
QUOTE (JRehling @ Oct 24 2020, 07:24 PM) *
Looking at the apparent fragility of those "rocks" I wonder what is going to happen during the high g forces during entry. None of it will vanish, but it might lose some of the original structure.
First, more interesting will be whether there are clathrates and volatiles that decompose on the return, or during reentry.
More worrisome is whether they will be lost in a "burp" when the sample return container is opened.

Second, (I haven't read the sample return protocol, so excuse the presumptions, BUT) I'm hoping they're going to amend the sample retrieval process to include dropping the sample return capsule in mylar-kevlar and then dunking the entire sample return into liquid nitrogen to prevent any further decomposition of clathrates or loss of volatiles.

Third, this sounds like a WONDERFUL opportunity to seek funding for a "WildFire" sample analysis module on the ISS. Something where you could keep samples in a micro-gravity environment, at cryogenic temperatures, while "decanting" them from probes.
HSchirmer
QUOTE (rlorenz @ Oct 25 2020, 10:16 PM) *
In theory, yes (I think I remember reading a scifi story where a stowaway on a spacecraft is discovered this way).

"The Cold Equations" https://docs.google.com/viewer?a=v&pid=...MmU1OTQ2YWViOWY
pbanholzer
Here's an article on contamination control for the SRC. Capturing/identifying sample outgassing is addressed in section 7.2 (and maybe other places I didn't catch).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350808/
Hungry4info
OSIRIS-REx in the Midst of Stow
https://www.asteroidmission.org/?latest-new...e-midst-of-stow

QUOTE
Today, after the head was seated into the SRC’s capture ring, 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 SRC.
Marcin600
NASA will host a media teleconference at 4 p.m. EDT (8 p.m. = 20:00 UTC) today, Thursday, Oct. 29 - stream live at: http://www.nasa.gov/live

"During the teleconference, OSIRIS-REx team members will discuss how the stowage process has gone so far, what else they have learned about the sample, and what the next steps are for the mission to return the sample to Earth." (here)
Marcin600
From teleconference: 400 g was visible in the camera, but they calculate that in reality there is currently maybe even well over 1 kg of samples in the TAGSAM head !!!

Most of the visible rocks (in the photos - flying around the TAGSAM head) are very flat - like corn flakes



The parcel is now packed and ready to ship to Utah:
Explorer1
Dante just said that the navcam was taking images (not yet released) that will show some of the surface effects from the thrusters and direct contact. So even if there's no return to Bennu's proximity, there should be some neat before/after images to look forward to.
Marcin600
From teleconference (+/-): "...The fact that TAGSAM has penetrated about 48 cm into regolith shows that the cohesive forces in regolith are very, very weak. There is almost no force between the crumbs that hold them together. The TAGSAM head sank in the regolith like in fluid...The same would happen with astronauts who would try to walk on an asteroid - they would sink into regolith to a depth depending on whether they were standing on loose soil, on a boulder or on some bedrock..."

https://www.youtube.com/watch?v=8kJLM87KGgQ...eature=emb_logo (starts around 13:27)
49:00 - 50:30
Marcin600
From teleconference (+/-): "...The ship's return engines left clear marks on the surface and launched a lot of debris... The regolith deeper below the surface appears to be composed of much smaller fragments than those visible on the surface..."

https://www.youtube.com/watch?v=8kJLM87KGgQ...eature=emb_logo (starts around 13:27)
1:07:24 - 1:09:55
Marcin600
Once again Dante Lauretta statement about Bennu's regolith, this time I post an exact transcription from the recording of the teleconference on YouTube (47:17 - 51:22):


Ivan Carone (AFP): „What have you learned from Bennu’s soil thanks to this operation and, to make it simple, if someone was to walk on Bennu what do you think it would be like?”

Dante Lauretta: „(...) i’ll just go back a little bit in time here and then and I did this after the TAG event I went back to a science team meeting from 2014 where we were discussing the possible interactions of TAGSAM with the Bennu soil or the regolith during the collection event. We had multiple teams trying to model this process. It seems like it should be straightforward but it’s actually pretty chellenging because you’re in a microgravity environment and all of the literature and all the previous studies that we were looking at the gravity field is a major component in describing the soil behavior in response to various forces. So, the question we were grappling with is how does the soil beheve when you remove gravity from the equation and all the other forces start to play a role. We’re particulary interested in understanding the cohesive forces between grains and any frictional forces that could arise due to the compression. The predctions ranged from we would penetrate three meters to we would penetrate three millimeters! So, it was really not helpful for me, except that we had a kind of a range of predictions based on inferred regolith properties.

Since we penetrated, we estimate, about that 48 cm, that’s much much closer to a very low cohesion regolith model. Basically there’s almost no forces between the grains that keep them bound together. They are not sticking to each other in any way. So when you slide two grains past each other there’s no force that really seems to be measasurable that’s prohibiting that motion. So, when the TAGSAM head made contact with the regolith, it just flowed away like a fluid.

And I think that’s what would happen to an astronaut if she were to attempt to walk on the surface of the asteroid. She would sink to her knees or deeper, depending on how loose the soil was until you hit a larger boulder or some kind of bedrock.

So, that’s already I can guarantee you the team is off now that we have this ground truth calibration data set to re-evaluate models of asteroid geology, and especially soil response and soil creep, and mass wasting, and other movements on the surface of the body. So, it’s fascinating that there was so little resistance to the spacecraft from the asteroid surface. Basically it’s kind of like a ball pit at a kid’s playground right you kind of jump into it and you just sink in. And that’s what the spacecraft did. And so luckily we had those back away thrusters to reverse the direction of motion, or we might have just flown all the way through the asteroid smile.gif "


Ivan Carone (AFP): "But do you think it could go very deep, like this kind of low cohesion?"

Dante Lauretta: "Yeah, I believe the model suggested, like I said, to three meters of penetration in a completly cohesionless environment, and that seems to be the way the soil responded. We were moving at almost full velocity after we made contact, and the deceleration that we experienced before the back away thrust was primarily from the TAGSAM, recall that the TAGSAM collects material by ejecting nitrogen gas, it’s basically like a cold gas thruster. And if we hadn’t done that and we hadn’t fired the back way thrusters, there was no resistance that’s measurable coming from the actual asteroid regolith."
mcaplinger
QUOTE (Explorer1 @ Oct 29 2020, 01:03 PM) *
Dante just said that the navcam was taking images (not yet released) that will show some of the surface effects from the thrusters and direct contact.

While waiting for these (I have no idea when they will be released) one could amuse oneself figuring out what they might look like relative to the SamCam images (SamCam is 20x20 degrees and basically pointed at the TAGSAM head); Navcam1 has an FOV of 21x16 degrees and is rotated 6 degrees about Y and -70 degrees about Z. I've never seen a good visualization of this and it's pretty confusing. All of this stuff is in https://naif.jpl.nasa.gov/naif/data_comet.html [EDIT: these images were taken with what is being called Navcam 2 or NFTCam; we called it Navcam1 when we were building it, but I guess they swapped the numbers?]
Hungry4info
Absolutely spectacular video of the sampling. We see the ejecta blanket expanding away from the impact site and creating the massive shadow we saw earlier. I've uploaded one of the frames. This is amazing. Best thing I've seen since the New Horizons image of Pluto back-lit from the sun.

TAG Captured by NavCam 2
https://www.asteroidmission.org/navcam2_tag...lete_small_gif/

Marcin600
A little lightened. Could it be a crater? (dug by one of the return engines)
Marcin600
Animated gif
FOV
Click to view attachment

I agree Hungry4info. Spectacular. My messing about with filters and such.
Marcin600
a little earlier - and closer
Marcin600
edge of the hole ?
Marcin600
first stages
Explorer1
Wow! dusting off the old swear jar! The liquid metaphor from the telecon is a great description, it really looks like its seething. Spaceflight image of the year!

Too bad about not returning to Bennu to see the wider view, but a bird in the hand (or SRC) is worth two in the bush, as they say.
Marcin600
the second stage

I wonder if all these thin, elongated shadows (almost black, thick lines) are the silhouettes of flat grains of regolith right next to the camera?
Brian Swift
Before and After. Frames 274 and 469 from NavCam2_TAG_single_loop_complete_small_gif.gif.
"After" frame has been brightened by 2.5x to better match "before".
The rocks(boulders?) along the right and bottom edge of "after" image can be matched to "before" image which covers a somewhat wider area.
Click to view attachment
Marcin600
QUOTE (Brian Swift @ Oct 31 2020, 08:25 AM) *
Before and After. Frames 274 and 469 from NavCam2_TAG_single_loop_complete_small_gif.gif.
"After" frame has been brightened by 2.5x to better match "before".
The rocks(boulders?) along the right and bottom edge of "after" image can be matched to "before" image which covers a somewhat wider area.
Click to view attachment


Looking at this brilliant before-after compilation, it now seems to me that all these dark areas and other things are happening on or above the surface, and that it is not a crater or a depression after all.
PS Of course except the pre-existing shallow crater (the target of the operation). These black areas can be hanging clouds or spots of very fine, dark debris (?)
Greenish
Agree that these are fantastic images, most inspiring to get engaged with for me since some of the early Curiosity stuff.

Dusting off some of my tool from then (like StereoPhotoMaker, which has improved!) here's some quick pseudo-3D views from nearby frames at the end of the sequence. Contrast stretched.

Cross-eye view
Click to view attachment
"Rotating illusion" gif (click to animate)... this one I turned 90 deg because it was easier for me to visually process.
Click to view attachment
Greenish
And here are two more, from adjacent frames (no shadow appearing suddenly and the disparity is less exaggerated). Also rotated so the motion is ~horizontal to align with eye separation.
crosseye: Click to view attachment
gif:Click to view attachment

QUOTE (Marcin600 @ Oct 31 2020, 08:27 AM) *
... seems to me that all these dark areas and other things are happening on or above the surface, and that it is not a crater or a depression after all.
PS Of course except the pre-existing shallow crater (the target of the operation). These black areas can be hanging clouds or spots of very fine, dark debris (?)


From these shots it appears to me that the dark areas are shadowed by the curtain of suspended material. What look like streaks of light under the "sheet" of particles are really cool, and there does appear to be a depression. Edit: The center of the impact zone is at about at the edge of the frame by this part of the sequence.
Marcin600
My attempt to make "before-and-after" animation (frames: 279 and 476):
Marcin600
Now it looks to me as if a cloud of debris was coming from the top of the photo (from the sampling site) and was being pushed from the bottom left corner (by the engine blast?). A black veil is created where the cloud thickens (on the border of the interaction of these two forces). This thickened veil also seems to cast a shadow towards the left and bottom of the photo...
This is just my speculation.
Greenish
Animated movie of the 'blast,' starting from where ground becomes visible again.
Click to view attachment

Full-res all frames here: https://imgur.com/a/Wp8swJD... had to make it pretty small, and use every other frame, to upload here as a GIF.

(I did NOT think this would work. All the hard part done by those who implemented the SIFT-based stack alignment tools in ImageJ! It is quite possible there are some distortions, but I'm learning as I go.)
monty python
Wow Greenish! Emptied my wallet into the swear jar.
Guillermo Abramson
QUOTE (Greenish @ Nov 1 2020, 01:46 AM) *
Animated movie of the 'blast,' starting from where ground becomes visible again.


Oh, this is the one that convinced me. Thanks!
Guillermo
Marcin600
QUOTE (Greenish @ Nov 1 2020, 05:46 AM) *
Animated movie of the 'blast,' starting from where ground becomes visible again.
Click to view attachment

Full-res all frames here: https://imgur.com/a/Wp8swJD... had to make it pretty small, and use every other frame, to upload here as a GIF.

(I did NOT think this would work. All the hard part done by those who implemented the SIFT-based stack alignment tools in ImageJ! It is quite possible there are some distortions, but I'm learning as I go.)


I just can't stop looking at this movie. Outstanding compilation!!!

Although the movement of the cloud relative to the surface is probably slightly exaggerated (?) by the movement of the camera and the associated change in the angle of view, you can still see the huge dynamics of the debris! And this amazing creep of shadows on the surface! It looks a bit like a version of a dust storm with large stones in it. Very unique and informative shots!

I would love to see what's in the black area at the top and outside of the pictures, in the place where TAGSAM "touched" the surface. I wonder if we will see such pictures from a distance?
Marcin600
My rough attempt to put the post sampling picture in the context of Nightingale, including scale and orientation of the picture.
I used this Nightingale mosaic and frames 279 and 476 of the NavCam 2 TAG animation.
As the shots from NavCam 2 were taken slightly obliquely to the Bennu surface, there is a shortening of the perspective compared to the mosaic and some view distortion.
Marcin600
And also an attempt to superimpose a post sampling picture on the Nightingale mosaic
Marcin600
SamCam and NavCam 2 Imaging Footprint During TAG - now "officially" on the OSIRIS-REx website
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