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Unmanned Spaceflight.com _ OSIRIS-REx _ Asteroid approach

Posted by: Holder of the Two Leashes Aug 24 2018, 06:48 PM

NASA update on the OSIRIS-REx mission, includes first picture of the asteroid from the spacecraft.

https://www.nasa.gov/feature/goddard/2018/nasas-osiris-rex-begins-asteroid-operations-campaign

Posted by: B Bernatchez Oct 6 2018, 10:33 PM

First Approach Maneuver completed:

https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-executes-first-asteroid-approach-maneuver


Posted by: Explorer1 Oct 19 2018, 02:12 PM

New images! (they will be leaving the '8-bit' phase pretty soon)

https://www.asteroidmission.org/bennu-oct-2018-pixel-zoom/

Posted by: mcaplinger Oct 19 2018, 04:16 PM

QUOTE (Explorer1 @ Oct 19 2018, 06:12 AM) *
https://www.asteroidmission.org/bennu-oct-2018-pixel-zoom/

When I first read this I assumed that there was an error in the captions: at a little under 10,000 km range Bennu is only 3.7 pixels in Polycam? But it's true, and that just goes to show how dinky Bennu is. Polycam's IFOV is 13.5 urad so at range R Bennu (246 meters mean radius) subtends 0.246*2/(R*13.5e-6) pixels.

Posted by: Explorer1 Oct 24 2018, 08:03 PM

https://www.asteroidmission.org/bennu-jupiterosirisrexobservations/

New image, plus a comparison with the Jupiter observation from last year to illustrate the albedo difference. Seems like another Ryugu so far....

Posted by: Hungry4info Oct 26 2018, 01:18 AM

New rotation movie from 3000 km taken on 23 Oct 2018. We can see surface features, even if it's not clear exactly what they are.

https://www.asteroidmission.org/bennu-13px/

Posted by: Phil Stooke Oct 26 2018, 05:37 AM

These are the 3 frames in that short movie, a bit processed. One suggests a crater, maybe bigger (relatively) than any on Ryugu.

Phil


Posted by: mcmcmc Oct 29 2018, 01:39 PM

Countdowns:
https://programmi.000webhostapp.com/osiris/osiris-counter.html

They are based on odd data: "future telemetries" available as "http://www.asteroidmission.org/wp-content/uploads/2018/10/, which always says 00:00 is the time of the maneuvers, and http://www.asteroidmission.org/wp-content/uploads/2018/10/SPP-Approach-Poster-10-03-18.pdf, I don't know where to find better data.

Posted by: mcmcmc Oct 29 2018, 02:39 PM

QUOTE (mcmcmc @ Oct 29 2018, 02:39 PM) *
Countdowns:


Found more rich but less embellished countdowns:
http://www.whereisroadster.com/osiris_rex/

Posted by: Paolo Oct 30 2018, 07:41 PM

https://www.asteroidmission.org/20181029t1019ut_bennu/

looking a lot like Ryugu

Posted by: Phil Stooke Oct 30 2018, 09:43 PM

One very good thing about this is that I can use exactly the same map projection for Bennu as I used for Ryugu. Only the scale has to change.

Phil

Posted by: mcmcmc Oct 31 2018, 01:44 PM

These direct query links to NASA Horizons provide objects distance from the Sun in km:

https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&CENTER=%20%27500@0%27&MAKE_EPHEM=%20%27YES%27&TABLE_TYPE=%20%27VECTORS%27&STEP_SIZE=%20%271%20m%27&OUT_UNITS=%20%27KM-S%27&REF_PLANE=%20%27ECLIPTIC%27&REF_SYSTEM=%20%27J2000%27&VECT_CORR=%20%27NONE%27&VEC_LABELS=%20%27YES%27&VEC_DELTA_T=%20%27NO%27&CSV_FORMAT=%20%27YES%27&OBJ_DATA=%20%27NO%27&VEC_TABLE=%20%276%27&START_TIME='2018-10-31%2014:40'&STOP_TIME='2018-10-31%2014:41'&COMMAND='-64'
https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&CENTER=%20%27500@0%27&MAKE_EPHEM=%20%27YES%27&TABLE_TYPE=%20%27VECTORS%27&STEP_SIZE=%20%271%20m%27&OUT_UNITS=%20%27KM-S%27&REF_PLANE=%20%27ECLIPTIC%27&REF_SYSTEM=%20%27J2000%27&VECT_CORR=%20%27NONE%27&VEC_LABELS=%20%27YES%27&VEC_DELTA_T=%20%27NO%27&CSV_FORMAT=%20%27YES%27&OBJ_DATA=%20%27NO%27&VEC_TABLE=%20%276%27&START_TIME='2018-10-31%2014:40'&STOP_TIME='2018-10-31%2014:41'&COMMAND='1999%20RQ36'

Look for "$$SOE" in result; distance in km is value 3 counting from 0.
Resulting current distance between OSIRIS-Rex and Bennu:
2018-Oct-31 14:40 - 236.16 km

It looks quite precise despite the big distance: this method gives 7 km as Hayabusa2-Ryugu distance, which is https://programmi.000webhostapp.com/hayabusa2/simulator/haya2-dates-5000.html.
I think the distance is based on light travel time.

Posted by: mcaplinger Oct 31 2018, 04:09 PM

There are SPICE kernels for Orex at https://naif.jpl.nasa.gov/pub/naif/ORX/kernels/ -- AFAIK this is what the flight team is using.

Posted by: mcmcmc Oct 31 2018, 04:58 PM

QUOTE (mcaplinger @ Oct 31 2018, 05:09 PM) *
There are SPICE kernels for Orex at https://naif.jpl.nasa.gov/pub/naif/ORX/kernels/ -- AFAIK this is what the flight team is using.

I have no idea of what SPICE kernels are. rolleyes.gif

Posted by: mcaplinger Oct 31 2018, 08:44 PM

QUOTE (mcmcmc @ Oct 31 2018, 08:58 AM) *
I have no idea of what SPICE kernels are. rolleyes.gif

They are files that capture the position and orientation of spacecraft and solar system bodies, used for mission planning and data analysis. https://naif.jpl.nasa.gov/naif/aboutspice.html

If NASA Horizons does what you want, then by all means use it. I'm not certain how frequently it's updated, however.

Posted by: mcmcmc Nov 1 2018, 04:21 PM

QUOTE (mcaplinger @ Oct 31 2018, 09:44 PM) *
They are files that capture the position and orientation of spacecraft and solar system bodies, used for mission planning and data analysis. https://naif.jpl.nasa.gov/naif/aboutspice.html

If NASA Horizons does what you want, then by all means use it. I'm not certain how frequently it's updated, however.

It's not clear to me how these data about spacecrafts are produced; are they recorded data up to current date and calculated data from now on? i.e. are they daily updated? or just calculated from mission schedules? OSIRIS data clearly show the trajectory correction maneuvers occurred during last months, but Hayabusa data show almost constant distance 7000m from Ryugu for same period, which is not true because Hayabusa actually passed from 20.000 to 20m and the other way round several times.

Posted by: djellison Nov 1 2018, 05:34 PM

QUOTE (mcmcmc @ Nov 1 2018, 08:21 AM) *
It's not clear to me how these data about spacecrafts are produced; are they recorded data up to current date and calculated data from now on? i.e. are they daily updated? or just calculated from mission schedules?


Yes. All of the above. Sometimes they are reconstructed. Sometimes they are predicted. Sometimes updated very regularly. Sometimes not. Metadata is usually included to explain the source of the data used.

Posted by: Phil Stooke Nov 2 2018, 08:07 PM

An approach GIF was just released - these are the 4 best frames, rescaled. The surface is becoming clearer.

Phil


Posted by: Hungry4info Nov 6 2018, 01:22 AM

https://www.asteroidmission.org/bennu-at-160-and-200-px/


 

Posted by: Explorer1 Nov 6 2018, 03:46 AM

Interesting dark patches in the southern hemisphere on the right image, and what might be a crater on the far right limb?
EDIT: rotation movie out! I'll leave it to the experts.... https://www.asteroidmission.org/bennu-rotation_20181102/

Posted by: charborob Nov 6 2018, 09:09 PM

https://www.asteroidmission.org/bennu-rotation_20181102/

Posted by: Phil Stooke Nov 7 2018, 12:10 AM

Beautiful! That should be enough for a preliminary shape model and map.

Phil

Posted by: mcmcmc Nov 7 2018, 11:13 AM

QUOTE (Phil Stooke @ Nov 7 2018, 01:10 AM) *
Beautiful! That should be enough for a preliminary shape model and map.

Phil

Shape model (just look, don't touch :-( ):
https://twitter.com/3Dmattias/status/1059936642612502529

Posted by: walfy Nov 8 2018, 06:05 AM

Here's a quickly rotating GIF in 3D of it, with contrast boost. Will post a slower next.


Posted by: walfy Nov 8 2018, 06:11 AM

This version spins much slower, at 3 second intervals, less jarring on the eyes:



Posted by: Phil Stooke Nov 8 2018, 07:33 AM

Nice! And another way of presenting the data in the animation, a set of frames. The last one is a repeat of the first one. A bit of a contrast stretch was applied.

Phil


Posted by: Roman Tkachenko Nov 9 2018, 01:17 PM

Asteroid Bennu Rotation (3D animation)


Posted by: mcmcmc Nov 12 2018, 09:15 PM

Interactive video:
http://win98.altervista.org/space/exploration/osiris/player/rotation.html
(allow several seconds until all 250 frames load).


Updated monitoring page:
http://win98.altervista.org/space/exploration

Posted by: charborob Nov 23 2018, 07:53 PM

https://www.asteroidmission.org/bennu-at-300-px/

Posted by: Spock1108 Nov 24 2018, 09:07 AM

Bennu is really very small compared to Ryugu, it's as big as Itokawa ... but why doesn't Itokwa have the same shape?




Posted by: Holder of the Two Leashes Nov 30 2018, 05:17 PM

I guess the best word I can think of here is "ironic".

Hayabusa 2 was planned with three sample acquisitions in mind, with the idea of getting diverse samples. But Ryugu turned out to appear fairly homogeneous so now they are only planning one sample (what about the sub surface sampling though? But I digress... ).

Then you have OSIRIS-REx only planning one single sample grab from Bennu.

I know they haven't reported anything yet about any of Bennu's compositional differences but, well... just look at it.

Technically, they could make three tries at sampling, provided the canister didn't fill up on the first try, so I wonder if they might rethink things.

Also, I'm a little worried at this point. OSIRIS-REx seems to be counting on there being dust and small pebbles for its sampling. It is still too far from Bennu to tell, but if the surface turns out to be like Ryugu with nothing but larger pebbles and rocks available, I wonder how they will deal with that.

Posted by: tanjent Nov 30 2018, 07:08 PM

That's a nice side-by side comparison of the three bodies, and it is consistent with the unexpectedly rocky surface of Ryuku and likely Bennu too.

Isn't that how panning for gold works? If you put heterogeneous gravel in a pan and agitate it, the smaller particles will settle to the bottom and the larger chunks will "float" to the top, even if they are intrinsically denser, because their irregular shapes prevent them from packing together as tightly. So in a rubble pile asteroid, the finer material will tend to migrate to the center. Itokawa probably had a bit more structural rigidity than the other two, at least enough to prevent this sorting process from proceeding quite so far.

The similar slightly oblate shapes of Ryugu and Bennu seem to reflect a balance between centrifugal force and their minimal gravity which may prove to be the norm for very loosely accreted piles of variously-sized junk.
If so, it may well complicate the sample collection process as Holder suggests.

Posted by: Adam Hurcewicz Dec 2 2018, 01:05 PM

OSIRIS-REx Arrival to Bennu (3-18 Dec 2018)


https://www.youtube.com/watch?v=Yrc4jR3Gy5M


I use SPICE (bsp,bc,tsc,tpc,tf) files from NAIF/NASA
Model of OREX is from NASA 3D models converted to cmod.

Soft is Celestia 1.7 64bit

More info apout arrival :
https://www.asteroidmission.org/asteroid-operations/



Posted by: Daniele_bianchino_Italy Dec 3 2018, 11:30 AM

I allowed myself to revisit Emily's comparison (Itokawa + Ryugu) and add asteroid Bennu:


Posted by: PhilipTerryGraham Dec 3 2018, 05:55 PM



This is what I'm assuming to be new, higher-resolution MapCam imagery. This GIF is featured on the mission's front page and the "spacecraft imagery" page, but clicking on the link (https://www.asteroidmission.org/?attachment_id=12095#main) leads to a 404... Anyways, many congratulations to the OSIRIS-REx team for completing the long journey to Bennu! I wish nothing but the very best for the mission ahead!

Posted by: Holder of the Two Leashes Dec 3 2018, 07:08 PM

At the OSIRIS-REx website, the caption for the above image sequence reads as follows:

QUOTE
This series of images taken by the OSIRIS-REx spacecraft shows Bennu in one full rotation from a distance of around 50 miles (80 km). The spacecraft’s PolyCam camera obtained the thirty-six 2.2-millisecond frames over a period of four hours and 18 minutes.

Date Taken: Nov. 25, 2018

Instrument Used: OCAMS (PolyCam)

Credits: NASA's Goddard Space Flight Center/University of Arizona


Congratulations to the spacecraft team for a successful arrival today!

Posted by: vjkane Dec 3 2018, 08:31 PM

I suspect it may take a lot of careful planning to find a safe touchdown surface on that asteroid.

Posted by: ElkGroveDan Dec 3 2018, 08:54 PM

The first thing that stands out is how unusually sharp and angular the surface debris appears.

Posted by: Y Bar Ranch Dec 4 2018, 02:33 AM

The animation makes it look like boulders should be flying off of it left and right. wink.gif

It'd be interesting to run a "Project Crowbar" to lever off one of the bigger boulders and drag/toss it into orbit for a full grapple and analysis.

Posted by: elakdawalla Dec 4 2018, 06:17 AM

I pride myself on being able to discern solar system worlds, but if it were not for Ryugu's special polar boulder and Bennu's "pimple" boulder I would not be able to tell the two apart without consulting reference images.

Posted by: Hungry4info Dec 5 2018, 12:33 AM

One thing that will help will be that the camera views aren't going to be constantly at full phase.

Here's Bennu at half phase from MapCam.
https://www.asteroidmission.org/20181203_mapcam/

Posted by: nprev Dec 5 2018, 03:13 AM

Sure is a jagged little beast. Makes me wonder if the regolith is relatively fresh with less thermal & micrometeoritic weathering than we've seen on other comparable bodies.

Posted by: HSchirmer Dec 5 2018, 04:03 AM

QUOTE (tanjent @ Nov 30 2018, 07:08 PM) *
...
Isn't that how panning for gold works? If you put heterogeneous gravel in a pan and agitate it, the smaller particles will settle to the bottom and the larger chunks will "float" to the top, even if they are intrinsically denser, because their irregular shapes prevent them from packing together as tightly.


Actually, what you're describing is "the Brasil Nut Effect" and there's even a paper on this
"The spherical Brazil Nut Effect and its significance to asteroids" https://academic.oup.com/mnras/article-pdf/443/4/3368/6291556/stu1388.pdf

Panning for gold is kinda the opposite, based on bulk density rather than grain size. Since gold is denser than stone, it is retained in the pan, or settles out into the grooves of a sluice, or if you're really old-school, settles out in the wool of a sheepskin...

Posted by: Holder of the Two Leashes Dec 5 2018, 05:47 PM

https://www.asteroidmission.org/20181203_mapcam/ taken seven hours before arrival by MapCam (click on link).

There will be a press conference December 10th to discuss the initial scientific results from approach, along with presentations at the AGU (American Geophysical Union) meeting on the 11th and 12th.

https://www.asteroidmission.org/osiris-rex-agu-2018/

QUOTE
Get ready for some asteroid science. Now that OSIRIS-REx has arrived at Bennu, the mission team will be presenting the initial results of their scientific studies of the asteroid during the spacecraft’s Approach Phase. The highlights will be discussed at a press conference on Dec. 10 at the American Geophysical Union’s fall meeting in Washington, DC. For conference attendees, three special scientific sessions in collaboration with JAXA’s Hayabusa2 mission will explore the early results from both missions in more detail on Dec. 11 and 12

Posted by: Steve5304 Dec 7 2018, 01:05 PM

QUOTE (Holder of the Two Leashes @ Dec 5 2018, 05:47 PM) *
https://www.asteroidmission.org/20181203_mapcam/ taken seven hours before arrival by MapCam (click on link).



The thing on the bottom left looks like a flat curled up sheet blink.gif

Its probably an optical illusion but man this thing has definitely collected a lot of rocky stuff over the years. Much different than Ryugu


Full Rotation

https://www.asteroidmission.org/?attachment_id=12182#main

Posted by: Holder of the Two Leashes Dec 10 2018, 06:45 PM

News conference ready to start in fifteen minutes. (2pm EST December 10th)

http://live.projectionnet.com/AGUPress/FM2018.aspx

Posted by: pbanholzer Dec 11 2018, 02:24 AM

QUOTE (Holder of the Two Leashes @ Dec 10 2018, 12:45 PM) *
News conference ready to start in fifteen minutes. (2pm EST December 10th)

http://live.projectionnet.com/AGUPress/FM2018.aspx



The AGU link has expired but it is available on Youtube https://www.youtube.com/watch?v=WRCzK8uZvoY

Posted by: elakdawalla Dec 11 2018, 06:46 PM

Here are a few images from the https://fallmeeting.agu.org/2018/files/2018/12/AGU-Press-Event_HR-Revision_FINAL_SMALL_SIZE.pdf, including a color MapCam portrait. If you break the MapCam view down into its channels, you can see that they didn't reproject the images before combining them into an RGB product -- there's evident rotation of the asteroid between red, green, and blue channels. They're also massively stretched. Can any of you image processing sorcerers do a better job with the image processing and maybe create a nice color portrait of Bennu?


 

Posted by: elakdawalla Dec 11 2018, 06:58 PM

This is the best I can do -- please someone here do better than me so I don't have to post this garbage on my website tongue.gif

 

Posted by: Ian R Dec 12 2018, 12:18 AM

Here's a mediocre effort of my own, Emily laugh.gif


Posted by: charborob Dec 22 2018, 08:03 PM

https://www.asteroidmission.org/bennunorthpolepassdec4/.

Posted by: kenny Jan 1 2019, 12:17 PM

OSIRIS-REx has successfully entered orbit around Bennu.
It is orbiting a mere 1 mile (1.75km) from the centre of the asteroid !

More details here...

https://solarsystem.nasa.gov/news/805/nasas-osiris-rex-spacecraft-enters-close-orbit-around-bennu-breaking-record/

Happy New Year to all, and looking forward to an extraordinary few days in solar system exploration...

Posted by: MarkG Jan 1 2019, 10:18 PM

[quote ...It is orbiting a mere 1 mile (1.75km) from the centre of the asteroid !
[/quote]

I believe the orbital period is 62 hours, which makes the orbital velocity about 3 meters/minute, 50mm/sec. (10ʻ/min, 2"sec).


Posted by: Marcin600 Jan 23 2019, 12:11 AM

New image - Bennu’s south pole: https://www.asteroidmission.org/mapcam-south-pole-flyby-20181217t061345/

I see a nice little crater with a flat bottom and a typical (?) grouping of large boulders in the pole region

 

Posted by: Explorer1 Feb 28 2019, 04:45 AM

Very nice high-res view near the north pole: https://www.asteroidmission.org/mapcam-north-pole-20190220/

Posted by: Marcin600 Mar 14 2019, 09:55 PM

New pics - region of Bennu’s northern hemisphere close up: https://www.asteroidmission.org/2019-02-25-regolith-image-compilation-3/
with: "pond” of regolith that is mostly devoid of large rocks" and "15 meter boulder"

Posted by: Hungry4info Mar 19 2019, 07:24 PM

Bennu has plumes! (or perhaps rather ejections of material)

QUOTE
Shortly after the discovery of the particle plumes on Jan. 6, the mission science team increased the frequency of observations, and subsequently detected additional particle plumes during the following two months. Although many of the particles were ejected clear of Bennu, the team tracked some particles that orbited Bennu as satellites before returning to the asteroid’s surface.

The OSIRIS-REx team initially spotted the particle plumes in images while the spacecraft was orbiting Bennu at a distance of about one mile (1.61 kilometers). Following a safety assessment, the mission team concluded the particles did not pose a risk to the spacecraft. The team continues to analyze the particle plumes and their possible causes.

https://solarsystem.nasa.gov/news/877/nasa-mission-reveals-asteroid-has-big-surprises/



More images:
https://svs.gsfc.nasa.gov/13154

Posted by: Explorer1 Mar 20 2019, 03:37 AM

So Bennu apparently has temporary moons every once in a while. I wonder if the spacecraft could get close to one of the larger ones to resolve it. Hopefully the team is confident these events won't be too big a deal and they can narrow the site they occur (I wouldn't want one nearby during sample collection!).

Posted by: PhilipTerryGraham Mar 20 2019, 05:42 AM

So we've uncovered a contact binary KBO that's really flat, and a Near-Earth asteroid that's spewing rocks into its orbit. What other weeeird stuff is 2019 gonna give to us, I wonder? On topic though, has the OSIRIS-REx team been able to locate where the sources of these ejections are on Bennu? I anticipate that'll be a new priority.

Posted by: nprev Mar 20 2019, 06:30 AM

Hard to think of anything that would cause this aside from straight-up thermal expansion. Pockets of volatiles sublimating would presumably produce far more energetic (and dense, and visible) plumes.

Maybe it does something similar at aphelion when contraction happens, or maybe that's just how the mechanical energy gets 'loaded' for perihelion passage burps like these. Still...without any significant surface gravitation that's not gonna cause much compression of surface materials at all.

Regardless: Cool. That's why we're here. smile.gif

Posted by: stevesliva Mar 20 2019, 02:06 PM

You mention thermal and mechanical/gravity. There's also electrostatic...

Posted by: Gerald Mar 20 2019, 02:09 PM

Agreed, https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015JA021738 may do it, as well. Even a weak repulsive force would be sufficient. I think, that 10V are considered reasonable in direct sunlight. Impacts of micrometeorites might be another approach. Tracking particles, and their acceleration due to solar radiation pressure and some potential weak electrostatic field could clarify the physics at work. Those fields would change with solar irradiation.

Posted by: Marcin600 Mar 20 2019, 07:11 PM

Or maybe Bennu is a body reassembled from fragments scattered after a relatively recent breakdown by impact and it is still undergoing a rearrangement of its surface (creation of the equatorial ridge) under the influence of its own gravity. Such small surface movements could throw small particles into space (?)

Posted by: bsharp Mar 21 2019, 12:56 PM

Image processing artifacts or a lot more particles orbiting around Bennu?

Cranked up brightness levels in original image https://www.asteroidmission.org/?attachment_id=15595


Posted by: fredk Mar 21 2019, 03:14 PM

Recall that that press release image was a composite of two frames, differing by a factor of a few thousand in shutter speed. So if you're referring to the arc of bright pixels reaching clockwise around Bennu from the main "jet", the sharpness of that arc's inner edge suggests that edge is the splice between the two frames. Since the outer exposure was much longer, it was probably picking up some glare from the main asteroid's body, which appeared as a sprinkling of bright pixels.

The main "jet" would appear much, much fainter (or be invisible) if this was a single exposure.

Posted by: bsharp Mar 21 2019, 06:17 PM

QUOTE (fredk @ Mar 21 2019, 04:14 PM) *
Since the outer exposure was much longer, it was probably picking up some glare from the main asteroid's body, which appeared as a sprinkling of bright pixels.


Thx, yes, I guessed just as much. The other composite (posted here yesterday) shows the glare and the thorough identification process by the team, this wouldn't have escaped them. "Jet" particle sizes were said to be cm size, even as much as 30cm.

Posted by: tolis Mar 21 2019, 08:04 PM

if memory serves, the charge-to-mass ratio of cm-sized particles would be far too low for electrostatic forces to play a role. This is some combination of day-to night thermal cycling + rotational state + composition.

Posted by: Roman Tkachenko Mar 27 2019, 05:41 PM

This 3D visualization is based on my preliminary 3D shape model and data taken by NASA's OSIRIS-REx spacecraft.

https://youtu.be/QRWdBoQm7J0

Posted by: Phil Stooke Mar 27 2019, 07:11 PM

Very nice!.

Here is a map of Bennu. The main part of the surface is derived from a map on the mission website which extends from 70 N to 70 S. I had to fudge the poles (as we cartographers say) from other images. A couple of rocks have informal names (The Gargoyle is one of them), which I will add when I figure out where they are. If anyone knows of any other informal names let me know.

The map projection is the same as I used for the Ryugu map, as they are so similar in shape.

Phil


Posted by: elakdawalla Mar 27 2019, 08:46 PM

Nice map! I believe that the rock at 45S 130E is "Ben-Ben." https://twitter.com/elakdawalla/status/1079919898514485248

Posted by: charborob Mar 27 2019, 10:09 PM

https://www.asteroidmission.org/bennus-boulder-1-stereo-pair-cross-eyed-version/

Posted by: Marcin600 Apr 7 2019, 05:04 PM

New pictures on the OSIRIS-REx website:
Bennu’s Equatorial Ridge - https://www.asteroidmission.org/20190329-fb4-equator-view/,
Global Mosaic with a coordinate grid - https://www.asteroidmission.org/bennu-sides-and-global-mosaic/ ,
3D view from Laser Altimeter (OLA) measurements - https://www.asteroidmission.org/bennu-visualized-by-ola-large/

and collection of 7 Nature papers (free and with many interesting pictures and conclusions) - https://www.asteroidmission.org/?latest-news=osiris-rex-special-collection-nature


 

Posted by: Marcin600 Apr 7 2019, 07:22 PM

Two Bennu's pictures ( https://www.asteroidmission.org/20190329-fb4-equator-view/ and https://www.asteroidmission.org/?attachment_id=15551#main), turned, cropped and brightened (as Bennu is very dark) - give a bit of sense of view from above the surface

I added a scale

For future astronauts, the terrain would be difficult to move around (large boulders everywhere), and microgravity would probably not help walking (constant danger of "flying away" into space)

I think it would be a bit like trying to walk on the bottom of the sea with an oxygen bottle on your back. This would require lengthy practice. And no one, even a large rock, gives support, because it can "fly away" with you. Anyway, big boulders, carelessly pushed too much and fluttering around your head is quite scary vision.


 

Posted by: Marcin600 Apr 11 2019, 10:21 PM

Interesting photos from OSIRIS-REx:
really huge boulder in the northern hemisphere - https://www.asteroidmission.org/20190307-polycam-northern-boulder/
cracked boulders on the equator - https://www.asteroidmission.org/20190307-polycam-cracked-rock/
I changed the first one slightly

 

Posted by: Marcin600 Apr 12 2019, 07:47 PM

More beautiful boulders: https://www.asteroidmission.org/20190307-southern-boulder-region/
(I love big boulders in small worlds cool.gif )
Many meteor collectors (including me) would like to have such "pebble" - it is CM chondrite, like Murchison (or something very similar)

 

Posted by: Daniele_bianchino_Italy Apr 14 2019, 09:03 AM

This revolutionizes a bit how I imagined the surface of asteroids forever and how we all imagined it, I think. It does not seem something anomalous or alien but something very common, any valley of terrestrial stones that is often found in the high mountains. I am trying to imagine the men in scale in these photos, exploring among those numerous rocks and I realize that there are so many that it would be difficult to walk there. So many "common" rocks let me think of the remains a part of an already existing and exploded world rather than an agglomeration formed with millions and millions of years. I probably can't conceive.
[]

Posted by: Marcin600 Apr 15 2019, 10:17 PM

"Benben" - largest boulder on Bennu: https://www.asteroidmission.org/20190307-polycam-benben/

(I found in reliable Wikipedia: "Benben was the mound that arose from the primordial waters Nu upon which the creator deity Atum settled in the creation myth of the Heliopolitan form of ancient Egyptian religion. The Benben stone (also known as a pyramidion) is the top stone of the pyramid. It is also related to the Obelisk." - https://en.wikipedia.org/wiki/Benben

And for fun, and for scale - a brave future astronaut exploring this huge rock with pickax wink.gif


 

Posted by: Marcin600 Apr 16 2019, 01:29 AM

QUOTE (Daniele_bianchino_Italy @ Apr 14 2019, 11:03 AM) *
This revolutionizes a bit how I imagined the surface of asteroids forever and how we all imagined it, I think. It does not seem something anomalous or alien but something very common, any valley of terrestrial stones that is often found in the high mountains. I am trying to imagine the men in scale in these photos, exploring among those numerous rocks and I realize that there are so many that it would be difficult to walk there. So many "common" rocks let me think of the remains a part of an already existing and exploded world rather than an agglomeration formed with millions and millions of years. I probably can't conceive.
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"So many "common" rocks let me think of the remains a part of an already existing and exploded world rather than an agglomeration formed with millions and millions of years."

In the case of Ryugu, according to http://science.sciencemag.org/content/early/2019/03/18/science.aaw0422, one of the models of its origin assumes that it (or rather its parent body) was broken into pieces by catastrophic impact and reaccumulated, at least a couple of times! Maybe the same applies to Bennu (?)

 

Posted by: AndyG Apr 16 2019, 10:36 PM

I need help here.

I can see a protoplanetary disc containing silicon and oxygen, and I can see these elements combining to make molecules that may later join together to form rock-dust-bunnies, bonded by electrostatic forces.

Here on Bennu I'm looking at consolidated rocks, alongside other 'conglomerates' that do not appear, at least at first glance, as particularly rock-like.

What is the step from dust to solid rock? Does it imply gravity (there's precious little here), heat from impacts (but, then, what keeps the dust together in such a collision?)

How does it potentially occur?

Andy


Posted by: Marcin600 Apr 16 2019, 11:26 PM

QUOTE (AndyG @ Apr 17 2019, 12:36 AM) *
I need help here.

I can see a protoplanetary disc containing silicon and oxygen, and I can see these elements combining to make molecules that may later join together to form rock-dust-bunnies, bonded by electrostatic forces.

Here on Bennu I'm looking at consolidated rocks, alongside other 'conglomerates' that do not appear, at least at first glance, as particularly rock-like.

What is the step from dust to solid rock? Does it imply gravity (there's precious little here), heat from impacts (but, then, what keeps the dust together in such a collision?)

How does it potentially occur?

Andy


Remember that small rocky asteroids like Bennu or Ryugu are not substantially primordial bodies, but formed from the breakdown of much, much larger asteroids. On these larger parent bodies (primordial), gravity was much higher, impact resistance was greater and, at the beginning, there was a lot of heat from the decomposition of short-lived elements, like aluminium (aluminum smile.gif isotope Al26

Posted by: Marcin600 Apr 16 2019, 11:34 PM

As far as I know, the details of the transition "from dust to rocks" are not well known (?) and it is being investigated (and its vision changes) before our eyes! The only "truly" primordial object we have seen so far is Ultima Thule, but it has a different composition (a lot of "ice"), because it is located (and always was there) far from the Sun.

Posted by: alan Apr 17 2019, 08:44 PM

The popular model these days is that in the protoplanetary disk dust grews into pebbles, probably mm sized in the inner solar system. In some parts of the disk these be came concentrated enough by one of a variety of of mechanisms to undergo a gravitational instability which caused clumps of them to collapse into asteroids ~100km in diameter. The consolidated rocks would form in these asteroids and be broken up and scattered in later collisions.

Posted by: JRehling Apr 18 2019, 01:53 AM

My understanding, via meteorites:

Parent bodies were either differentiated (large enough to have possessed sufficient radiogenic heat to melt) or not. From those that were smaller, we have chondrites, whose solid minerals date back to the first millions of years after the origin of the solar system. Chondrites have iron in abundance along with other stone – a lot like the overall composition of the Earth or Venus if you count the cores and mantles both – but in the chondrites, iron and stone are mixed on a fine level.

From larger parent bodies, exemplified near the larger end by Vesta, we have achondrites. Like smaller versions of the Earth and Venus, these were large enough to melt through, and their iron descended into a core, leaving a relatively iron-poor mantle/crust. Meteorites from Vesta therefore have elemental composition approximately like the crusts of Earth or Venus.

Bennu sure looks like some interesting geology has taken place, but it is classified as carbonaceous and is thus likely a fragment of a smaller, undifferentiated parent body rather than a larger one. If so, we'll expect to find higher levels of iron when we get those samples.

http://meteorites.wustl.edu/metcomp/index_files/image002.gif

Posted by: charborob May 10 2019, 02:05 AM

Looking at the published images of Bennu (https://www.asteroidmission.org/galleries/spacecraft-imagery/), I noticed that two of them could be stitched together:


Posted by: Marcin600 May 14 2019, 11:46 PM

https://www.asteroidmission.org/20190329-benben-north/ (nicknamed Benben) - rotaded, brightened and with scale bar. In the third picture for scale is Apollo 12 astronaut Pete Conrad with Surveyor 3


 

Posted by: Marcin600 May 15 2019, 12:45 AM

And a bit more "free" version of https://www.asteroidmission.org/20190329-benben-north/ with Apollo 12 astronaut Pete Conrad with Surveyor 3 for scale

 

Posted by: climber May 15 2019, 08:08 PM

Why did you choose the shortest men on the Moon? biggrin.gif

Posted by: Marcin600 May 15 2019, 08:32 PM

QUOTE (climber @ May 15 2019, 10:08 PM) *
Why did you choose the shortest men on the Moon? biggrin.gif


Because he was most photogenic wink.gif

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