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
First Approach Maneuver completed:
https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-executes-first-asteroid-approach-maneuver
New images! (they will be leaving the '8-bit' phase pretty soon)
https://www.asteroidmission.org/bennu-oct-2018-pixel-zoom/
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....
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/
These are the 3 frames in that short movie, a bit processed. One suggests a crater, maybe bigger (relatively) than any on Ryugu.
Phil
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.
https://www.asteroidmission.org/20181029t1019ut_bennu/
looking a lot like Ryugu
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
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.
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.
An approach GIF was just released - these are the 4 best frames, rescaled. The surface is becoming clearer.
Phil
https://www.asteroidmission.org/bennu-at-160-and-200-px/
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/
https://www.asteroidmission.org/bennu-rotation_20181102/
Beautiful! That should be enough for a preliminary shape model and map.
Phil
Here's a quickly rotating GIF in 3D of it, with contrast boost. Will post a slower next.
This version spins much slower, at 3 second intervals, less jarring on the eyes:
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
Asteroid Bennu Rotation (3D animation)
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
https://www.asteroidmission.org/bennu-at-300-px/
Bennu is really very small compared to Ryugu, it's as big as Itokawa ... but why doesn't Itokwa have the same shape?
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.
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.
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/
I allowed myself to revisit Emily's comparison (Itokawa + Ryugu) and add asteroid Bennu:
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!
At the OSIRIS-REx website, the caption for the above image sequence reads as follows:
I suspect it may take a lot of careful planning to find a safe touchdown surface on that asteroid.
The first thing that stands out is how unusually sharp and angular the surface debris appears.
The animation makes it look like boulders should be flying off of it left and right.
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.
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.
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/
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.
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/
News conference ready to start in fifteen minutes. (2pm EST December 10th)
http://live.projectionnet.com/AGUPress/FM2018.aspx
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?
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
https://www.asteroidmission.org/bennunorthpolepassdec4/.
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...
[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).
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
Very nice high-res view near the north pole: https://www.asteroidmission.org/mapcam-north-pole-20190220/
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"
Bennu has plumes! (or perhaps rather ejections of material)
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!).
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.
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.
You mention thermal and mechanical/gravity. There's also electrostatic...
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.
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 (?)
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
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.
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.
This 3D visualization is based on my preliminary 3D shape model and data taken by NASA's OSIRIS-REx spacecraft.
https://youtu.be/QRWdBoQm7J0
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
Nice map! I believe that the rock at 45S 130E is "Ben-Ben." https://twitter.com/elakdawalla/status/1079919898514485248
https://www.asteroidmission.org/bennus-boulder-1-stereo-pair-cross-eyed-version/
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
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.
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
More beautiful boulders: https://www.asteroidmission.org/20190307-southern-boulder-region/
(I love big boulders in small worlds )
Many meteor collectors (including me) would like to have such "pebble" - it is CM chondrite, like Murchison (or something very similar)
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.
[]
"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
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
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.
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.
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
Looking at the published images of Bennu (https://www.asteroidmission.org/galleries/spacecraft-imagery/), I noticed that two of them could be stitched together:
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
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
Why did you choose the shortest men on the Moon?
Two of the recently posted images of Bennu could be stitched together:
Four candidate sample sites on Bennu have been selected.
https://www.asteroidmission.org/?latest-news=nasa-mission-selects-final-four-site-candidates-asteroid-sample-return
Granted it's in bold at the bottom of the release, but I almost missed it... this web-media feature has a bunch of imagery and discussion and analysis of all four sites:
https://www.asteroidmission.org/candidate-sample-sites/
Nice animation (and explanation) https://www.asteroidmission.org/?latest-news=flyover-candidate-sample-sites of the four possible sites (definitely do a full screen on this).
John
Surprisingly regular pattern of cracks on Bennu's boulder ( from https://www.asteroidmission.org/20190720largefracturedboulders/ ).
The beauty of natural physical processes common in the Universe...
The down selection to a primary and backup sampling site could occur as early as today.
In the meantime here are a couple of article links. One is an update and another is about a close call that almost postponed the sampling a great deal.
LINK: https://phys.org/news/2019-12-nasa-osiris-rex-midst-site.html
LINK: https://phys.org/news/2019-12-osiris-rex-asteroid-mission.html !!!
Quote from the end of the second article:
It will be Nightingale. Osprey is the backup site.
Spaceflight Now Article: https://spaceflightnow.com/2019/12/12/nasa-selects-site-for-osiris-rex-to-collect-asteroid-samples/
New, detailed pictures of the surface of Nightingale, taken January 22, 2020 from 600 m - on https://www.asteroidmission.org/galleries/spacecraft-imagery/ (and also nice mosaics).
Pictures: NASA/Goddard/University of Arizona, slightly changed.
More https://www.asteroidmission.org/galleries/spacecraft-imagery/ from a 600 m (pictures from OSIRIS-REx: NASA/Goddard/University of Arizona, slightly changed)
The first one looks a bit like cracked erratic with glacial polish
From the OSIRIS-Rex https://www.asteroidmission.org/?latest-news=status-update-osiris-rex-osprey-flyover: "On Feb. 11, NASA’s OSIRIS-REx spacecraft safely executed a 0.4-mile (620-m) flyover of the backup sample collection site Osprey... Preliminary telemetry, however, indicates that the OSIRIS-REx Laser Altimeter (OLA) did not operate as expected during the 11-hour event. The OLA instrument was scheduled to provide ranging data to the spacecraft’s PolyCam imager, which would allow the camera to focus while imaging the area around the sample collection site. Consequently, the PolyCam images from the flyover are likely out of focus. The other science instruments... all performed nominally during the flyover... The mission team is currently reviewing the available data from the flyover in order to fully assess the OLA instrument..."
First official (approved by IAU) Bennu surface feature https://www.asteroidmission.org/?latest-news=first-official-names-given-to-features-on-asteroid-bennu: 11 boulders (Saxum) and 1 Regio.
Most prominent boulder (22 m high) is officially designated Benben Saxum.
Time to update my map! No craters are named yet but I expect we will get a few more names later. When I can get a version of the new map without text I will put it into this map.
Phil
Google translate: saxum == stone. That's a new one to me.
I enjoy this sort of thing. Had to give my doctor wife a hard time when I discovered the posterior fossa isn't where I'd expect it to be.
This is a new category in the Solar System nomenclature. So far, "saxum's" (actually: Saxa) names https://planetarynames.wr.usgs.gov/nomenclature/SearchResults;jsessionid=43216D2C193AE5B5EBA185A642EAC75E only for Ryugu (only 3, e.g. Otohime Saxum) and Bennu (11).
PS. When I hear: "posterior fossa", I think about one of these things (I know it's Chasma - not fossa - on Tethys, but it looks good):
https://www.asteroidmission.org/bennu_global_mosaic/ - version without text
New, sharp and amazing resolution https://www.asteroidmission.org/20200303pebblesincrevices/ from 0.3 km
https://www.asteroidmission.org/20200303blockrock/ of surprisingly geometric shapes of boulders on Bennu
Marcin600 - yes, I just noticed the mosaic has been released without names. When I can get to it I will put it in my map.
Phil
Polar projections...
Here's some more info about Natural Feature Tracking.
https://www.nasa.gov/feature/goddard/2020/bennus-boulders-shine-as-beacons
Somehow, this blurb completely omits describing the camera being used for NFT or the organization that built it.
As far as I can tell, the plan is still to execute the first TAG rehearsal in April.
At some point we may want a new thread.
Here is a new map using the recently-released mission map as background.
Phil
https://astrogeology.usgs.gov/news/nomenclature/twelve-new-names-approved-for-bennu
A new set of names for Bennu's rocks, added to those already given. I will get them on the map as time permits. Nice to see Thorondor among them, me being a Tolkien addict from way back.
Phil
OK, now I'm adding the locations of the three particle ejection events reported so far.
Phil
Hmm. Three. And all in the same hemisphere. Ain't that kinda curious . . .
Three debris fields . . . hmm again:
Let's abstract the situation: Three relatively closely spaced points on a roughly spherical object make a triangle.
Now toy with it . . . connect each point with the center of its opposing side to find the triangle's centroid (where the lines intersect inside the triangle); extending those lines across [around?] the opposite hemisphere determines another point of intersection.
Use this antipodal intersection point to interrupt the surface and "unpeel" it along those extended medians a little bit——say 30 arc-degrees so we stay well distant from the debris fields——and use that extent of unpeeling-the-orange to create a Constant-Scale Natural Boundary map well suited to comprehensively study the debris fields and their interactions if any.
Alternatively, assuming no access to CSNB software, use
1) the antipodal point as the edge of an azimuthal equidistant projection to get a standard map crudely suitable for the same purpose, with severe distortion causing trouble only within say 30º of the map's edge. This won't be a problem if semi-orbital dust transport is not in play. The severe edge distortion can be eliminated by
2) an Oblique Peirce Quincuncial projection centered on the nearside centroid, rotated so the cross is a best fit with the medians. You'll get four far-side 45º "flaps" instead of the three 30º flaps you'd get with CSNB, so expect some map-edge interruption of the debris fields if semi-orbital dust transport is occurring. This could be minimized by
3) Setting up a digital 3-D model and glancing back and forth between it and either of the imperfect conventional maps and——assuming you've got above-average short-term memory——thereby sniffing out airborne debris interactions if any.
Just thinking out loud while Sopranos S2 E13 loads . . .
Greetings to you all,
Looking back on two recent images of Bennu proposed by Marcin:
http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=45133
http://www.unmannedspaceflight.com/uploads/post-7860-1584699384_thumb.png
I'm not a geologist, but I know the cleavages and cleavage planes in mineralogy or crystallography, the sometimes surprising forms that nature offers us and all things proper to cause our perplexity.
For the case of these geometric forms on this scale, present on a rubble pile, does anyone have explanations, hypotheses or even ideas that would distance us from mere chance?
Are you aware of other similar examples in the large catalogue of spatial imaging of asteroids?
Straight-line fractures ("joints") are pretty common on Earth- here's https://classconnection.s3.amazonaws.com/201/flashcards/2107201/jpg/joint1354150305467.jpg. They are a natural result of tectonic or other stresses in homogeneous rocks, and are different from the cleavage patterns you see in single crystals. The interesting question is what type of stresses (impact? thermal?) might do this on an asteroid surface.
John
Bennu originated as a fragment of a larger body, so both the breakup event and the possible forces within the parent body seem to be more likely sources of fractures than anything that would occur in a body the size of Bennu.
Since „...the most prominent joints occur [on Earth] in the most well-consolidated, lithified, and highly competent rocks, such as sandstone, limestone, quartzite, and granite...” (https://en.wikipedia.org/wiki/Joint_(geology)), I think we can say - at least - that these two specific boulders (rock fragments) on Bennu are quite compact, and not „fluffy”, like http://www.hayabusa2.jaxa.jp/en/topics/20200318_nature/. But such rocks on Bennu are probably an exception, because so far only very few such geometric cracks have been photographed (?)
I'm not geologist, but I would bet on thermal stress for the reasons for these cracks.
Alternatively, it may have something to do with generating of stresses in rocks during collisions (impacts) - - maybe even on the parent body (although this second stone seems to have broken quite "recently" - on a cosmic time scale).
Hello Marcin,
Some remarks to explain my point of view :
The object of my curiosity concerns the geometric shapes on the scale of the meter with two images that you had posted, namely a large straight fracture and what seems to me to be relatively flat surfaces with right angles.
Significant differences in daytime and nighttime T° can certainly cause rock fractures. But I’d be surprised if that were the case here, for a straight fracture approximately three metres long.
Even more, on the second image that I had selected, what appears as flat surfaces seen from above (Strata?) with right angles do not seem to me to be able to be explained by thermal, mechanical processes (impact) or others affecting an asteroid with a gravity as low as Bennu.
My advice is given with caution, because I know very little.
Quetzalcoatl, are you suggesting some sort of bedding on Bennu or his perent body? That would be an interesting issue.
For me, these rectangular forms and flat plates on this little asteroid are quite mysterious, but - as I wrote - I am not a specialist...
On the other hand, on comets, such as Churyumov-Gerasimenko, we have a fractal structure: from microcrystals, through crystals to very large structures - everything reflects the original way of forming. Maybe in these two boulders on Bennu we actually see some "huge, original crystal structure", but it seems to me quite unlikely...
I think the biggest problem is that we really know very little about the nature of these rocks, their structure, origin, mechanical properties, mineralogical composition, etc. That is why we need samples of Bennu rocks in Earth's labs so much. Having them in our hands (with a little luck there will also be tiny fragments similar in properties to these interesting boulders) we will solve many puzzles.
From https://en.wikipedia.org/wiki/Joint_(geology)#/media/File:Joints_Caithness.JPG - Orthogonal joint sets on a bedding plane in flagstones, Caithness, Scotland, Earth and negative picture:
Three days left until https://www.asteroidmission.org/?latest-news=rehearsal-time-for-nasas-asteroid-sampling-spacecraft
I wonder: can back-away burn at 75 m pick up any debris from Bennu's surface?
Any OSIRIS-REx navigation people here?
I'm wondering if SPICE kernels with predicts for Tuesday's “Checkpoint” rehearsal are publicly available anywhere.
The kernels I looked at from NAIF don't appear to include the maneuver.
A "trim" maneuver would be named TRnTn (fill in the n with some number). Two similarly named adjustments were cancelled according to this status report:
https://www.asteroidmission.org/status-updates/
I'm not sure what a "P" maneuver would be. Maybe phasing like you suggested. They did mention phasing burns in the status report.
Checkpoint rehearsal activities start today, April 14, at 2:45 pm EDT = 18:45 (6:45 pm) UTC - https://twitter.com/OSIRISREx
Operations plan - https://www.asteroidmission.org/wp-content/uploads/2020/04/Checkpoint-Rehearsal-Poster-9.pdf
https://www.asteroidmission.org/where-is-the-spacecraft/ is the current distance from Bennu - but I don't know how often it will be updated?
For years I have imagined the small meteorites that fall to Earth like small-craterized, black, burnt, melted rocks. Only when I was older did I discover that burnt and melt is given by the heat of the impact with the atmosphere. So I imagine that the small meteorites that fall on Earth and give rise a Fireballs, if we observed them before the impact with our terrestrial atmosphere, are common rocks, very similar to the terrestrial ones, one of the many as seen above the Bennu terrain in this picture (Am I saying well?):
http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=45604
Here's a text file with the predicted position of OREx in the Bennu frame every minute for 24 hours starting at 2020-04-14T00:00:00 (time X Y Z) as extracted from orx_200401_200421_200413_od240-N-TR1D-L-TR1BO_v1.bsp
tagr.txt ( 103.64K )
: 282
Here's a visualization of the March 3, 2020 low (250m) pass over Nightingale. https://youtu.be/Px9JpK9PtZ0
Everything https://www.asteroidmission.org/?latest-news=one-step-closer-to-touching-asteroid-bennu And in large part thanks to the remote work of OSIRISRex team, in spite of the f... virus!
https://www.asteroidmission.org/checkpoint-rehearsal-movie/ on the OSIRISRex website: SamCam pictures (covering 10 minutes of descent) from 120 to 65 m (so, a bit lower than the planned 75 m), with extended sampling arm
The approach test was a success. Here is Spaceflight Now's coverage of the event:
https://spaceflightnow.com/2020/04/15/osiris-rex-spacecraft-carries-out-first-of-two-rehearsals-before-sampling-asteroid/
If you'd like to walk around Bennu or set it on your desk, I've posted some AR Quick Look (Augmented Reality) globes at:
http://www.mandelbits.com/arworlds.html
These are viewable in Safari on devices running iOS 13 or later.
Nice new pictures from the latest Checkpoint Rehearsal on the OSIRS-REx website, e.g. https://www.asteroidmission.org/20200414navcamcheckpoint/.
Here is my (very limited) play with a view towards Bennu's horizon.
No, this is not a real panorama (it's from 115 m above the surface) - not yet, unfortunately...
[only Harrison Schmitt is missing - that's a request to Neo ]
Just for fun - limited edition of Bennu (for Mars lovers) :
A simulated panorama and fisheye view from 50m below checkpoint rehearsal lowest point.
https://flic.kr/p/2j17cVShttps://flic.kr/p/2j17cVS by https://www.flickr.com/photos/bswift/, on Flickr
https://flic.kr/p/2j17cU4https://flic.kr/p/2j17cU4 by https://www.flickr.com/photos/bswift/, on Flickr
Checkpoint Rehearsal visualization on YouTube https://youtu.be/y3q9UtEDXOQ
Touchdown delayed to October 20th:
https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-ready-for-touchdown-on-asteroid-bennu
https://www.asteroidmission.org/osprey-recon-c-mosaic-reduced-size/ of Osprey (backup site) on the OSIRIS-REx website - 347 PolyCam images collected on May 26 from 250 m, stitched together and corrected - 5 mm per pixel at full size!
Today, June 9, a very interesting article appeared in Nature Communications, regarding the issues we recently discussed in this forum thread:
https://www.nature.com/articles/s41467-020-16528-7.pdf
It has been summarized on the OSIRIS-REx website: https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-discovers-sunlight-can-crack-rocks-on-asteroid-bennu
Few quotes:
“...This is the first time evidence for this process, called thermal fracturing, has been definitively observed on an object without an atmosphere...”
„ ...[OSIRIS-REx] found evidence of exfoliation, where thermal fracturing likely caused small, thin layers (1 – 10 centimeters) to flake off of boulder surfaces. The spacecraft also produced images of cracks running through boulders in a north-south direction, along the line of stress that would be produced by thermal fracturing on Bennu...”
„...Meteoroid impacts do occur on Bennu and can certainly crack rocks, but they would not cause the even erosion of layers from boulder surfaces that were seen. Also, there’s no sign of impact craters where the exfoliation is occurring...”
“...We don’t have good constraints yet on breakdown rates from thermal fracturing, but we can get them now that we can actually observe it for the first time in situ,” said OSIRIS-REx project scientist Jason Dworkin of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Laboratory measurements on the properties of the samples returned by the spacecraft in 2023 will help us learn more about how this process works...”
NASA has released a mosaic picture of the prime landing site Nightingale.
Here is a https://www.nasa.gov/feature/goddard/2020/osiris-rex-produces-nightingale-mosaic to the news release which in turn will provide a link to picture selection.
The full resolution mosaic is 345 PolyCam images stitched together, at a resolution of 4mm, is a 152 MB download and is 14371 X 14488 in size.
https://www.asteroidmission.org/20200526samplingrocks/, close to Osprey - taken by OSIRIS-REx PolyCam on May 26, from 0.3 km
Earth and Moon seen from Asteroid Bennu
https://sbnarchive.psi.edu/pds4/orex/orex.t...ta_raw/orbit_a/
According to the mission's Twitter site, the matchpoint rehearsal appears to have gone okay. They are still downloading data so there is yet to be any formal news release or status update.
https://twitter.com/OSIRISREx
Video is up!
https://www.youtube.com/watch?v=a1IdyXAwDXQ
In preparation for the sampling I have updated my Bennu map. This uses a new paper in JGR-Planets to identify more particle ejection sites. With so many I have decided to remove the dates. Also added: dates of the imaging and rehearsal events for the candidate sites.
Phil
Here is an interesting abstract from the Apophis workshop coming up in November:
http://www.hou.usra.edu/meetings/apophis2020/pdf/2008.pdf
It's an extended mission for OSIRIS-REx, which would orbit Apophis in 2029. This is just one of several suggestions for Apophis missions at:
https://www.hou.usra.edu/meetings/apophis2020/pdf/apophis2020_program.htm
Phil
New, interesting results on the OSIRIS-Rex website: https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-to-asteroid-bennu-youve-got-a-little-vesta-on-you
"...six boulders (1.5 to 4.3 m) scattered across Bennu’s southern hemisphere and near the equator...[are] almost ten times brighter than their surroundings...
[Spectrum] signature from the boulders [analyzed by OVIRS spectrometer] was characteristic of the mineral pyroxene, similar to what is seen on Vesta and the vestoids..."
I just couldn't go to bed without adding those locations to the map. Very interesting!
Phil
That's an awesome map (I do have a soft spot for maps of strange and distant places)!
This is undoubtedly the best Bennu map!
I dream that one day Phil will make a complete atlas of small, non-spherical bodies of the Solar System (asteroids, comets, small moons) photographed so far by space probes
The first attempt of TAG sample collection event https://www.asteroidmission.org/?latest-news=osiris-rex-begins-its-countdown-to-tag
https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-unlocks-more-secrets-from-asteroid-bennu
- carbon-bearing, organic material -> bright veins on boulders made of carbonate -> Bennu’s parent asteroid had an extensive hydrothermal system
- Bennu’s “colors” variations -> Nightingale’s regolith has only recently been exposed to the space weathering
- two main types of boulders: 1: dark, rough, weaker and more porous, and 2: bright, smooth, stronger and less porous (host the carbonates) -> formed at different depths in the parent asteroid -> both types are weaker than expected -> dark boulders would not survive the journey through Earth’s atmosphere -> this type of material is not currently represented in meteorite collections
- 3D digital terrain model of Bennu at 20 cm resolution (Laser Altimeter data) -> revealed ridge-like mounds that extend from pole-to-pole; northern and southern hemispheres have different shapes
- gravity field of Bennu determined by tracking the trajectories of the spacecraft and the particles naturally ejected from surface -> interior of Bennu is not uniform -> pockets of higher and lower density material inside; a void at Bennu’s center, within which you could fit a couple of football fields; the bulge at equator is under-dense -> Bennu’s rotation is lofting this material...
I don't understand how you could have a void at the centre of Bennu; where would all the fine material absent from the surface have migrated to? Don't get me wrong, a hollow asteroid would be an amazing discovery, but the paper itself ( https://advances.sciencemag.org/content/6/41/eabc3350 ) does not mention the 'void' quoted in the articles.
"I dream that one day Phil will make a complete atlas of small, non-spherical bodies of the Solar System (asteroids, comets, small moons) photographed so far by space probes"
If people would stop doing things on the Moon and Mars I might have time for that.
Phil
NASA will carry a live broadcast of the first sample collection attempt on Tuesday.
LINK: https://www.nasa.gov/press-release/nasa-to-broadcast-osiris-rex-asteroid-sample-collection-activities
The packing density of a conglomeration of random fragments can be in the ballpark of 0.36.
Then, a region near the center packed at that density would give you the same under-density as if there were a complete void somewhat smaller than that region.
Whether or not a world could evolve such that the central region is less packed than the "mantle" is an exercise left to the reader.
https://www.pnas.org/content/pnas/early/2014/06/04/1403768111.full.pdf
Livestream of simulated spacecraft events has started, link here:
https://www.asteroidmission.org/livestream/
NASA TV will go live at 5:00 EST.
That's 5pm EDT, or 21:00 UT, for the live NASA TV coverage.
The OSIRIS REx team is updating their Twitter account fairly often for the current hours leading up to collection. For those wanting to check in with those updates between now and NASA TV going live (and maybe after) you can go https://twitter.com/OSIRISREx.
Coverage is live on https://www.nasa.gov/multimedia/nasatv/#public.
TAG completed! Spacecraft going back up!
Sampling complete! Now to get the images back and verify sample mass.
Outstanding!
One of the best parts of watching these live is seeing the joy of the team as years of hard work come to fruition. Congratulations to the people of OSIRIS-REx!!!!
Awesome. Now to see if they got enough sample.
Exciting !!!
From the https://www.nasa.gov/press-release/nasa-s-osiris-rex-spacecraft-successfully-touches-asteroid:
"The team can’t wait to receive the imagery from the TAG event late tonight and see how the surface of Bennu responded to the TAG event.”
“Our first indication of whether we were successful in collecting a sample will come on October 21 when we downlink the back-away movie from the spacecraft,” Moreau said. “If TAG made a significant disturbance of the surface, we likely collected a lot of material.”
"All spacecraft telemetry data indicates the TAG event executed as expected. However, it will take about a week for the OSIRIS-REx team to confirm how much sample the spacecraft collected."
Anyone have insight into why contact time (2020-10-20 21:50:10) from recent SPICE file
( orx_200827_201103_201019_od292-N-T1D-L-T1R1_v1.bsp )
was a 3 minutes off from actual time which was listed (with added light delay) in a press release on 10/14?
MEDIA ADVISORY M20-113 shows 6:12 p.m. EDT as collection time, -18.52min light travel time gives 21:53 UTC.
Data flowing to the DSN at 900 kbps. Press conference at 2 PM PDT today (10/21) on NASA TV.
IMAGES UP:
https://www.nasa.gov/feature/goddard/2020/osiris-rex-tags-surface-of-asteroid-bennu/
"Upon initial contact, the TAGSAM head appears to crush some of the porous rocks underneath it." (from https://www.nasa.gov/feature/goddard/2020/osiris-rex-tags-surface-of-asteroid-bennu/)
Dark porous rock crushed by the TAGSAM head (I think so):
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
Here is a re-timed version of TAG images, running about 2-3x realtime. https://youtu.be/6X10esr6Snw
The dark shadow of the debris cloud is especially impressive towards the end.
Would any images of the site taken later on to see surface changes? The official website says they are not returning to the vicinity if there is enough sample collected.
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'm asking the same question John. Some people suggest a crater could have formed due to nitrogen gas expulsion. Wait and see!
By the way, I played myself with the sequence of TAG images. Here I aligned on the ground several pictures taken when OSIRIS-REx moved away from Bennu:
https://www.flickr.com/photos/thomasappere/50516292028/sizes/o/
Since the shadows in the pictures are to the right of the stones (and not on the left), it seems to me that this big sharp shadow is caused by an object protruding above the surface - such as a nearby large boulder (located to the left and "up" from the field of view).
If it were a depression (the alleged crater), we would see its slope illuminated rather than shaded (shade opposite to that of stones).
So I think it's a big boulder and not a "crater".
All this is combined with a "fuzzy shadow" of a great mass of debris carried away by nitrogen and - above all - by the ship's engines
(picture "borrowed" from neo56)
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.
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
Is there a minimum weight requirement in the sample to be considered a successful sample return?
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
"...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" (https://www.nasa.gov/press-release/nasa-s-osiris-rex-spacecraft-collects-significant-amount-of-asteroid)
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
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!
"...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?
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?
Good idea. For everything happening post-boop please discuss it in this http://www.unmannedspaceflight.com/index.php?showtopic=8573.
Aligned sequence helping to show where the TAG happened.
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