Mission: Hayabusa 2 |
Mission: Hayabusa 2 |
Sep 11 2018, 03:42 PM
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#556
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
it's not the actual sampling operation, yet. it's the first rehearsal:
http://www.hayabusa2.jaxa.jp/en/topics/20180911e/ |
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Sep 12 2018, 02:58 AM
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#557
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Senior Member Group: Members Posts: 1418 Joined: 26-July 08 Member No.: 4270 |
We're about 1 km away now (if not less). The most recent image as of this post has a major data drop-out, but here's the most recent good image from UTC 2018-09-12 02:32.
Edit: A new image from UTC 2018-09-12 02:51. I'm pretty sure we can now see the spacecraft's shadow on the asteroid -- a dark smudge centered in the opposition surge that appears to be visible in both of the images in this post. -------------------- -- Hungry4info (Sirius_Alpha)
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Sep 12 2018, 03:27 AM
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#558
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Senior Member Group: Members Posts: 2082 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Good eye! I don't think it was visible in previous images, was it?
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Sep 12 2018, 03:52 AM
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#559
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Senior Member Group: Members Posts: 1418 Joined: 26-July 08 Member No.: 4270 |
Indeed. As far as I can tell, the two images in that post are the only two images where it is clearly visible, and I've not seen it in any previous image.
The site is giving me 404 errors right now, unfortunately. Edit: From https://twitter.com/haya2e_jaxa/status/1039723761728217089 QUOTE [TD1-R1] Currently, our real time navigation image gallery has halted. Please wait as we work on the problem. Operation of the spacecraft is continuing normally.
-------------------- -- Hungry4info (Sirius_Alpha)
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Sep 12 2018, 07:42 AM
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#560
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Newbie Group: Members Posts: 17 Joined: 15-August 15 Member No.: 7722 |
According to update in japanese Hayabusa2 descended to 600 m above sufrace and then autonomous system stopped the descent and began to rise, probably due to unabillity to measure distance by LIDAR because Ryugu's surface have very low reflectivity.
As for the spacecraft's shadow - it's clearly visible in several frames: /how can i reduce the size of inserted image? |
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Sep 12 2018, 02:03 PM
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#561
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
The reason for unexpected rise during H2 descent is as follows. My translation of the relevant description in Japanese.
We have been conducting a rehearsal for the first touch down since 10 September. The spacecraft started descending on 11 September. Today (12 September) H2 was going down to the lowest height intended, but its autonomous system ordered H2 to to rise and H2 started rising back to its HP. It is thought that the reason for this is LIDAR could not cope with the low reflectivity of Ryugu and could not measure the seperation distance well enough. H2 is now back at its HP ad is healthy. We will be looking again at the constants that had been given to H2 and also looking at possibility of improved sequence. P |
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Sep 12 2018, 02:10 PM
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#562
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Junior Member Group: Members Posts: 80 Joined: 18-October 15 From: Russia Member No.: 7822 |
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Sep 13 2018, 06:59 AM
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#563
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Senior Member Group: Members Posts: 1083 Joined: 19-February 05 From: Close to Meudon Observatory in France Member No.: 172 |
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Sep 16 2018, 06:05 AM
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#564
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
The spacecraft shadow and opposition effect
http://www.hayabusa2.jaxa.jp/en/topics/20180915e/ |
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Sep 18 2018, 11:29 PM
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#565
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Senior Member Group: Members Posts: 1418 Joined: 26-July 08 Member No.: 4270 |
A couple interesting tweets from their twitter feed. One about landing site imagery acquisition during the recent rehearsal attempt, and another about MINERVA-II1 rover deployment schedule.
QUOTE Although TD1-R1 was interrupted, we were able to see the response of Hayabusa2 at low altitude and gain a valuable image of the landing candidate area at high resolution. The Project Team feels that we are narrowing down the unexplored areas step by step. QUOTE This week we will deploy the MINERVA-II1 rovers! Tomorrow (Sept 19) is the preparatory operation prior to the descent and on the 20th, the spacecraft will start descending towards Ryugu. The separation of MINERVA-II1 is scheduled for the 21st.
-------------------- -- Hungry4info (Sirius_Alpha)
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Guest_mcmcmc_* |
Sep 19 2018, 07:50 AM
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#566
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Guests |
Cool.... but very uncomfortable, I feel like being driving (flying?) in reverse! Wouldn't it be better a rotation downwards? Or even better, from right to left, which probably gives a better 3d effect? |
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Sep 23 2018, 03:09 AM
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#567
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
Something has been bothering me a lot. It is as follows.
If an asteroid is made of hard metal and somewhow it is covered with sands and pebbles and rocks and if someting collides with it very hard resulting schock wave must be cataclysmic to shake them beyond escape velocity, leaving nothing but the metal asteroid. Craters on Ryugu seem to suggest that Ryugu is like a metal, soft metal, soft enough to leave crater holes but hard enough not to break up on impact. So, why are there regolith and boulders still left on Ryugu? Where did those boulders come from in the first place? I am trying to persuade myself that those shaken off Ryugu travelled into deep space and came back to where they started from after billions of years in the solar system. Am I going mad? P |
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Sep 23 2018, 03:29 AM
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#568
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Senior Member Group: Members Posts: 2082 Joined: 13-February 10 From: Ontario Member No.: 5221 |
There's probably no metal at all in Ryugu, it's more of a 'rubble pile', of low density rocks (just like Itokawa), with many voids and empty spaces inside. I'd guess the inside is as broken and fractured as the surface the cameras can show us.
The craters we see are all very soft, with rounded edges, and every impact just breaks off more pieces, which either don't have enough velocity to escape and come back as boulders (I'd guess the enormous one at the pole is one), or, if they have enough velocity, fly off as separate bodies, permanently. The ones we see now were all probably part of the original body when it first broke off in turn from its parent body eons ago, and have just been broken up and reformed, probably many times since. The impact projectile Hayabusa 2 is carrying is the perfect experiment to demonstrate this when they fire it at Ryugu. It should replicate the natural process on a smaller scale. |
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Sep 23 2018, 06:22 AM
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#569
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Member Group: Members Posts: 238 Joined: 15-January 13 Member No.: 6842 |
There's probably no metal at all in Ryugu, it's more of a 'rubble pile', of low density rocks (just like Itokawa), with many voids and empty spaces inside. I'd guess the inside is as broken and fractured as the surface the cameras can show us. The craters we see are all very soft, with rounded edges, and every impact just breaks off more pieces, which either don't have enough velocity to escape and come back as boulders (I'd guess the enormous one at the pole is one), or, if they have enough velocity, fly off as separate bodies, permanently. The ones we see now were all probably part of the original body when it first broke off in turn from its parent body eons ago, and have just been broken up and reformed, probably many times since. The impact projectile Hayabusa 2 is carrying is the perfect experiment to demonstrate this when they fire it at Ryugu. It should replicate the natural process on a smaller scale. Ryugu's extremely low gravity probably corresponds to it being a rocky rubble pile. If it were a solid metal asteroid, it would have a much stronger density and gravity, right? -------------------- Curiosity rover panoramas: http://www.facebook.com/CuriosityRoverPanoramas
My Photosynth panoramas: http://photosynth.net/userprofilepage.aspx...;content=Synths |
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Sep 23 2018, 10:28 AM
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#570
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Newbie Group: Members Posts: 11 Joined: 1-March 10 Member No.: 5237 |
If an asteroid is made of hard metal and somewhow it is covered with sands and pebbles and rocks and if someting collides with it very hard resulting schock wave must be cataclysmic to shake them beyond escape velocity, leaving nothing but the metal asteroid. the collision will result in huge fragmentation, generating a kind of cloud of material, which will collide each other and dissipate the energy, to the point their relative speed is reduced and accretion starts again. close observation of Ryugu and its reaction to the impactor is hence part of the evaluation of the theoretical descriptions. Patrick Michel is part of the Hayabusa scientific team, and he is an expert in simulation of such processes, movies illustrating the various mechanisms here : simulations of asteroid collisions |
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