OSIRIS-REx Asteroid Sample Return

[tater]

 

[tater]

 

[kerbiloid]

The wrecked Imperial Star Destroyer (right-down quadrant, exactly above the dark square shadow).

Spoiler

 

[cubinator]

It's interesting because we've all seen rocks with cracks and all kinds of textures, but the things that made these rocks look the way they do are completely different than how it happens on Earth. For instance, lots of these rocks have long, straight cracks! What's up with that? Did little meteor impacts chisel out big shards of rock? Or is it something else? 

[IonStorm]

On 8/28/2019 at 4:57 PM, cubinator said:

It's interesting because we've all seen rocks with cracks and all kinds of textures, but the things that made these rocks look the way they do are completely different than how it happens on Earth. For instance, lots of these rocks have long, straight cracks! What's up with that? Did little meteor impacts chisel out big shards of rock? Or is it something else? 

Earth rocks also can show linear cracks, but often with very different types or rocks than Bennu http://maps.unomaha.edu/maher/STEP07/supportinfo/cracks.html  There are phyllosilicates (clays) on the surface, they could exhibit a preferred fracture orientation.  It may be due to thermal fracturing, and perhaps related to the particle ejection events.  So much science to do.

[tater]

What a bizarrely wonderful little world...

[Geschosskopf]

I haven't looked at this mission in several months.  Now I see Bennu is so covered with boulders they've had trouble finding any places to "land" at all, and have had to rewrite the landing program to come down between all the boulders.  I'm glad they think they can make it work despite all the boulders.

It's too bad they can't just turn down their scatter setting  

[tater]

Wow.

 

[SuperFastJellyfish]

Two of the four possible sample sites from here:

Quote

This is the highest-resolution image of candidate sample site Sandpiper that has been captured to date. Located in asteroid Bennu’s southern hemisphere, Sandpiper is visible in the center of the image (situated above the large boulder). The image was taken on October 5, from a distance of 0.6 miles (1 km). For scale, the large, light colored boulder in the bottom center of the image is 16 ft (5 m) wide, which is about the size of a box truck.

Sandpiper with 16ft box truck units for scale-ish:

 

 

 

 

Quote

This is the highest-resolution image captured of candidate sample site Osprey as of October 12. Site Osprey is located just north of asteroid Bennu’s equator. Because the crater is so large, only a portion of it is shown in this image. Osprey’s recognizable features include a dark patch of material in the center of the crater, and a large, flat boulder on the northern crater wall (upper left). The image was taken on October 12, from a distance of 0.6 miles (1 km). For reference, the fracture in the large boulder (upper left) is 10 ft (3 m) long, which is about the length of a standing grizzly bear.

Osprey with grizzly bear units for scale-ish:

Edited October 25, 2019 by SuperFastJellyfish
Added scale imagery

[tater]

 

If you said that this image was the 1:1 with what I see on my monitor at full size---that the frame is 24cm across, in other words---I'd think, "that seems about right." Instead the frame is what, ~17m across? Amazing how there is no sense of scale at all. I'd bet that zoomed in it looks the same.

[StrandedonEarth]

4 minutes ago, tater said:

Amazing how there is no sense of scale at all. I'd bet that zoomed in it looks the same

Fractal-roids?

[tater]

 

[tater]

 

[tater]

Nightingale it is.

Good luck!

 

This with spacecraft graphic for scale is good:

 

[IonStorm]

It is a great site on a challenging asteroid.  Next are some low passes to get even better images, then some rehearsals in the spring for sampling in August!

[tater]

47 minutes ago, IonStorm said:

It is a great site on a challenging asteroid.  Next are some low passes to get even better images, then some rehearsals in the spring for sampling in August!

Cool, exciting times!

That Goddard tweet was particularly interesting because it gives scale, and shows how challenging your sample collection will be.

[IonStorm]

Now check out the videos

[Racescort666]

I know they describe asteroids as "rubble piles" but these high res pictures with OSIRIS-REx overlaid really puts it into perspective. It's literally a pile of rocks bound by gravity.

[AngrybobH]

8 hours ago, IonStorm said:

Now check out the videos

Those videos are amazing. Why was nightingale chosen over Osprey? From the looks of the video osprey looks easier to land in/on.

[IonStorm]

6 hours ago, AngrybobH said:

Those videos are amazing. Why was nightingale chosen over Osprey? From the looks of the video osprey looks easier to land in/on.

It was a complex series of analyses and models with more than just the topographic models.  We also used rock counting to the cm-scale, color variation, local tilts, and spectra.  Osprey has slightly better backaway vectors but a lower density of fine material.  So the probability of a successful contact times the probability of a successful collection for the two sites was about the same. After vigorous debate we selected Nightingale as prime and Osprey as backup and rejected the other two.  We received concurrence from headquarters that our rationale is sound.

8 hours ago, Racescort666 said:

I know they describe asteroids as "rubble piles" but these high res pictures with OSIRIS-REx overlaid really puts it into perspective. It's literally a pile of rocks bound by gravity.

Yes, we had modeled our pre-launch data based on Itokawa and expected vast smooth regions like the Muses-C regio and assumed worst case would be like the rough areas of Itokawa. 

Surprise!

[tater]

@IonStorm, Obviously the sample return container is sealed. After return, is it opened in a larger sealed container to analyze any volatiles that come off, or is there a connector to remove those gases first for analysis?

[IonStorm]

1 hour ago, tater said:

@IonStorm, Obviously the sample return container is sealed. After return, is it opened in a larger sealed container to analyze any volatiles that come off, or is there a connector to remove those gases first for analysis?

The sample return canister (SRC) is sealed, but not airtight.  There is a filter (Figure 1 and 2) allows the pressure inside to equalize with the outside during reentry without introducing water or heatshield ablation products.  Upon collection the SRC is kept under N2 purge to prevent ingest of moisture and contaminants.  Otherwise, the canister would need to be heavy enough to hold vacuum, which is more expensive than OSIRIS-REx can afford.  Also, based on the nitrogen agitation to collect the sample, the warm surface temperature of Bennu, and reentry heating we don't expect a lot of loosely bound gases so it would not have been a good use of resources to build an airtight and thus and heavier return capsule.  Instead we will be observing the gases that are evolved upon heating in the laboratory.

 

Fig 1. Note the location of the filter inside the SRC in panel b

Fig 2. Diagram of the filter

Filter performance and other fussy details can be found at https://rdcu.be/bYXUe

 

[IonStorm]

If you want to browse images from the ~six months of Bennu encounter (18 Oct 2018 - 12 April 2019), the complete image data set are public at the Planetary Data System in a simple GUI 

https://sbib.psi.edu/data/PDS-Bennu/

(unlike the usual PDS distribution method https://pds-smallbodies.astro.umd.edu/data_sb/target_asteroids.shtml#101955_Bennu)

[cubinator]

1 hour ago, IonStorm said:

If you want to browse images from the ~six months of Bennu encounter (18 Oct 2018 - 12 April 2019), the complete image data set are public at the Planetary Data System in a simple GUI 

https://sbib.psi.edu/data/PDS-Bennu/

(unlike the usual PDS distribution method https://pds-smallbodies.astro.umd.edu/data_sb/target_asteroids.shtml#101955_Bennu)

God, that is so weird to see a world map with averagely sized boulders and rocks instead of continents and islands...

[tater]