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Mission: Hayabusa 2
pandaneko
post Jun 10 2018, 09:40 PM
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I am not sure if this diagram reflects real situation, but it seems to me that at 1000km dishes will be pointing to us on earth
without having to turn the the satelite. Image size at 2500km was something like 3x3, so at 1000km we may be looking at
something like 50 pixels, and that may be something, no? Surely, JAXA will be tempted to take a few photos, no?



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nprev
post Jun 11 2018, 12:49 AM
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I'm sure they will for navigational purposes, but they may not be of much interest otherwise. Should provide a crude approximation of the shape, though.


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pandaneko
post Jun 11 2018, 07:48 AM
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TCM-2 done at 1300km, no more sideway thrusts needed. Ryugu is right in front of Hayabusa 2.

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pandaneko
post Jun 11 2018, 08:48 AM
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I want to see satelites around Ryugu, just one will do...

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Gustavo B C
post Jun 11 2018, 11:29 AM
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JAXA released another image of Ryugu, now from 1500 km away, taken yesterday. Still can't discern a shape, but it's now at -5.7 magnitude:



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mcmcmc
post Jun 11 2018, 12:09 PM
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June 10th, 1500 km away:

178 seconds exposure

Current resolution: 150 m/pixel
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Phil Stooke
post Jun 11 2018, 05:49 PM
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The latest image is over-exposed (or at least, processed to clip the histogram), rather than 'very bright' as the report suggests. But it's not completely washed out. There is a tiny bit of variation in the bright pixels. So maybe these are the first hints of surface features! Here's a version of the image processed to show the detail. Now, it could still be true that this is an artifact, but based on past experience with first glimpses of new worlds, I think it may be real. The dark spot is not completely symmetrical.

Phil

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mcmcmc
post Jun 11 2018, 05:53 PM
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QUOTE (Phil Stooke @ Jun 11 2018, 06:49 PM) *
The latest image is over-exposed (or at least, processed to clip the histogram)


The shot lasted 178 seconds w.r.t. 0.090 of the darker one.
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pandaneko
post Jun 12 2018, 07:52 AM
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I have not actually seen any of the staions in action before, but here it is. Apparently they had been at it for half an hour when
I opened the Haya2 web page. Thank yo, Goldstone!!!

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pandaneko
post Jun 12 2018, 08:09 AM
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Tyring to find out where Hayabusa 2 will be after return to the earth I searched i vain for clues in JAXA Facts sheet of April this year, and
I could not find anything there. Instead, I came across a few interesting remarks about Hayabusa 2 itself.

Not exactly completely new discoveries to many of us here, but I will carry them soon, becaiuse after all it is still popcorn time before
the main film starts, I think... and also, some people here must be very busy to notice minor things.

Here again, I really wish there were a few mini mini satelites around Ryugu, small ones, like bascket ball size... They will be cute!

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pandaneko
post Jun 12 2018, 08:11 AM
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The darker patch in the middle is a volcano?

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mcmcmc
post Jun 12 2018, 09:23 AM
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QUOTE (pandaneko @ Jun 12 2018, 09:09 AM) *
Here again, I really wish there were a few mini mini satelites around Ryugu, small ones, like bascket ball size... They will be cute!

I was just thinking about this: won't the SCI impact create a persistent cloud of debris orbiting around Ryugu? I think not all of the fragments will cross escape velocity.

Ore, there is maybe another possibility: rather than creating a crater, a 2kg copper bullet (around 6x6x6 cm) shot at 2 km/s could pass through the whole asteroid, if it is just a "pile of rubble" with almost no gravity to keep pebbles and sand and ice together...


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pandaneko
post Jun 12 2018, 01:14 PM
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I have been wondering how, from the plane on which ONC-W2 is located, on earth W2 can view anything of Ryugu and I have found
an answer to that. W2 is the donation camera. W2 can look down, not vertically downward, but at an angle. See the diagram!

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mcmcmc
post Jun 12 2018, 01:51 PM
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QUOTE (pandaneko @ Jun 12 2018, 02:14 PM) *
I have been wondering how, from the plane on which ONC-W2 is located, on earth W2 can view anything of Ryugu and I have found
an answer to that. W2 is the donation camera. W2 can look down, not vertically downward, but at an angle. See the diagram!

P

Very interesting and detailed video about all the cameras (visible, IR) onboard, with 3d visualizations of FOVs:
https://www.youtube.com/watch?v=LFh_pe3O_xM
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Phil Stooke
post Jun 12 2018, 05:17 PM
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"The darker patch in the middle is a volcano?"

Pandaneko, see the earlier post - you can't tell what something is unless there are many pixels across it. Here, one pixel is very slightly darker than those around it. Probably there is a small dark spot inside that pixel - a dark marking or shadow - much smaller than the pixel but big enough to make it, on average, a bit darker. No interpretation is possible yet. And my dark marking MIGHT just be an artifact. I think it's not but it might be.

But this is a testable hypothesis. When we get closer, and can see clearly, and know how the asteroid rotates, we will be able to figure out which bit of the asteroid was facing the camera when this image was taken. Then we can see if this is real or not.

(also - tiny rocks don't have volcanoes)

Phil


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