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Mission: Hayabusa 2
centsworth_II
post Sep 26 2018, 07:06 PM
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QUOTE (pandaneko @ Sep 26 2018, 05:27 AM) *
Here is my simplistic view of the formation of our solar system....
The sun is a second generation star so the solar system was not part of the first accretion events in the universe. We can study primordial objects in our solar system but unfortunately this will not be the same as studying the original primordial objects of the universe.
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pandaneko
post Sep 27 2018, 09:54 AM
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Apologies. I will stop talking about solar systems. Good timing because I was going to add more to mine. Thanks.

P
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neo56
post Sep 29 2018, 08:11 PM
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I'm having fun with Ryugu, putting it on major cities and capitals to give a sense of scale:

Paris


New York City


London


Tokyo


Rio de Janeiro


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djellison
post Sep 29 2018, 09:20 PM
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QUOTE (neo56 @ Sep 29 2018, 12:11 PM) *
I'm having fun with Ryugu, putting it on major cities and capitals to give a sense of scale:



Problem is - if you did that - it would collapse under terrestrial gravity into a conical rubble pile. biggrin.gif
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neo56
post Sep 30 2018, 07:01 AM
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QUOTE (djellison @ Sep 29 2018, 09:20 PM) *
Problem is - if you did that - it would collapse under terrestrial gravity into a conical rubble pile. biggrin.gif


Oooops laugh.gif from a diamond shape to a cone, that's less impressive.


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lyford
post Sep 30 2018, 05:50 PM
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QUOTE (neo56 @ Sep 29 2018, 11:01 PM) *
Oooops laugh.gif from a diamond shape to a cone, that's less impressive.

Angle of repose be dammed, your work helped me get a grasp of the size of Ryugu... Having a terrestrial reference has always helped for scale (like @fredk's mystery man in all the MER pans). Though, somewhere on the internets, someone will probably use on of those images to illustrate a NASA doomsday conspiracy cover up theory. tongue.gif


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djellison
post Sep 30 2018, 08:14 PM
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Well...early on in Cassini they kept putting out an image of Enceladus hovering over a MODIS image of the UK for scale.

I kept wondering....why do they want to crash it into Birmingham?

🤣
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kenny
post Oct 1 2018, 04:51 PM
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Looking at those wonderful images of asteroidal rubble, I can imagine many of those boulders slowly descending out of the sky over millennia, and just settling there quietly... do we think that's how Ryugu accumulated, gently?
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Phil Stooke
post Oct 1 2018, 08:23 PM
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No, I'm afraid its history has been a lot more violent.

Most likely, it began life as part of a much larger body which was eventually blown apart by a devastating collision. This and many other fragments dissipated and took on their own identities. Ryugu was itself hit by many small impactors which ejected some fragments altogether, but threw out others at lower speed, which fell back to build up a layer of fragments. Then one day a big impact shattered the whole body. Again, quite a lot was lost for ever but enough stuff was thrown out more slowly and collected again under its own cumulative gravity to form the pile of rubble you see today. Since then a few other impacts have made the craters we can see, ejecting some fragments and redistributing the rest.

The last part of that could be said to match your gentle accumulation description, but it was just a part of a brutal past.

Phil



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hendric
post Oct 1 2018, 09:36 PM
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This is one reason I am excited for New Horizons at Ultima Thule. Getting to see a hopefully unaltered body up close should help answer a lot of questions on small body growth at the birth of the Solar System. I'm betting, based on what we saw with Rosetta, that it will be covered in 2-5m scale boulders that gently gathered together, perhaps as a few larger bodies merged over time. I'm betting against a shattered rubble pile!

For Ryugu, the lack of dust is fascinating. Is it too small to hold onto any generated during impacts? Does the dust settle inwards as the rubble pile redistributes itself after each impact? Hopefully the rovers and sample return has some answers!


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marsbug
post Oct 1 2018, 11:05 PM
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QUOTE (Phil Stooke @ Oct 1 2018, 09:23 PM) *
No, I'm afraid its history has been a lot more violent.

Most likely, it began life as part of a much larger body which was eventually blown apart by a devastating collision. This and many other fragments dissipated and took on their own identities. Ryugu was itself hit by many small impactors which ejected some fragments altogether, but threw out others at lower speed, which fell back to build up a layer of fragments. Then one day a big impact shattered the whole body. Again, quite a lot was lost for ever but enough stuff was thrown out more slowly and collected again under its own cumulative gravity to form the pile of rubble you see today. Since then a few other impacts have made the craters we can see, ejecting some fragments and redistributing the rest.

The last part of that could be said to match your gentle accumulation description, but it was just a part of a brutal past.

Phil


I'm going to assume that's well informed speculation and deduction, rather than you having a blue police box parked in the corner of your garage 😁 My poor sense of humor aside (sorry man, you just give such a strong sense of witnessing the history of Ryugu) , such a violent history strike me as consistent with the apparent lack of hydration in the surface material, which surprised JAXA (I guess that's part of your reasoning? ) . But given such a well mixed object, might there not still be hope of finding comparatively unaltered material?


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Phil Stooke
post Oct 1 2018, 11:43 PM
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No... it's the police box.

Phil


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marsbug
post Oct 2 2018, 01:04 AM
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I knew it!!!


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elakdawalla
post Oct 3 2018, 04:57 PM
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Hi everybody, I'm doing a little forum maintenance. I've been remiss in organizing these asteroid mission subforums. There's now a separate Hayabusa2 subforum. I have split off the MASCOT posts into their own thread and also the MINERVA-II-1 posts into their own thread since it looks like people will be playing with those photos for a while. We'll keep this original thread open for general discussion. When it comes time to do the first sampling maneuver, we'll start a new thread for that, too.



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Guest_mcmcmc_*
post Oct 4 2018, 09:04 AM
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I found an official DLR log for H2 position, expressed in meter distance from center rather than from ground:
https://www.dlr.de/dlr/en/portaldata/1/scri...nt_decimals.csv
Ryugu radius is around 450 meters.

This will be instead useful during return to Earth (if updated):

https://www.dlr.de/dlr/en/portaldata/1/scri..._english_KR.txt

These data are used by the DLR simulators:
https://www.dlr.de/dlr/en/portaldata/1/scri...busa2/tall.html
https://www.dlr.de/dlr/en/portaldata/1/scri...abusa2/box.html

But it looks like they don't work properly.

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