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

Begins Operations

First Approach Maneuver completed:

https://www.asteroidmission.org/?latest-new...proach-maneuver

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

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.

https://www.asteroidmission.org/bennu-jupit...exobservations/

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

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

They are based on odd data: "future telemetries" available as "digital readouts", which always says 00:00 is the time of the maneuvers, and PDF schedule, I don't know where to find better data.

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

Bennu at 100 Pixels

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:

OSIRIS-Rex
Bennu

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 currently 5 km.
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.

I have no idea of what SPICE kernels are.

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.

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.

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

Phil

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Two Sides of Bennu

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/

Bennu full rotation at 200 pixels.

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

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

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

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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

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Asteroid Bennu Rotation (3D animation)

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


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

Bennu at 300 pixels.

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



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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/


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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:



Congratulations to the spacecraft team for a successful arrival today!

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.

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/...556/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...

High Phase Angle Picture 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.

Press Conference Page

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

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

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

LINK

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

Here are a few images from the press briefing materials shared yesterday, 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

Here's a mediocre effort of my own, Emily

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