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Mission: Hayabusa 2
pandaneko
post Apr 24 2018, 01:08 AM
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I know that there has been a kids contest about Ryugu's shape, but I am not too concerend about its shape.
Rather, I am becoming unsure of the success of the copper plate experiment. Below is the firiing video.

https://youtu.be/gmh2lGjXm7w

If Ryugu is very hard, then this copper firing may not result in a big dip on the surface?

Somewhere, and I do not remember exactly where off hand, but somewhere within Hayabusa 2 web page,
there is a huge data set of numbers, all hayabusa 2's position, all free to be used for educational
purposes. Prof Yoshikawa there talks about possibe use of this data set, like, calculating the actual
discrepancy, from two body calculation for students.

P
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djellison
post Apr 24 2018, 05:17 AM
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If you take that copper plate impact - and apply it to a rubble like surface, in basically zero-G - it'll do plenty of damage !
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pandaneko
post Apr 24 2018, 07:04 AM
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Also, if I come to think about it, the mass of whatever contains the gun powder. Hayabusa 2 is something like
600 kg, I think, but Hayabusa 2 will hide away behind the asteroid when the firing takes place. Perhaps,
copper place is very thin?

P
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Caotico09
post Apr 24 2018, 09:44 PM
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QUOTE (pandaneko @ Apr 24 2018, 01:04 AM) *
Also, if I come to think about it, the mass of whatever contains the gun powder. Hayabusa 2 is something like
600 kg, I think, but Hayabusa 2 will hide away behind the asteroid when the firing takes place. Perhaps,
copper place is very thin?

P


This link provides a bit more information: http://www.muses-c.isas.ac.jp/kawalab/astro/pdf/2011C_8.pdf
Basically, the easiest way to think about it.
- Hayabusa 2 will orient in respect to the asteroid.
- The impactor (SCI) will deploy from the spacecraft.
- Hayabusa 2 will burn around the asteroid.
- The SCI will detonate.
- The resulting jet/projectile formed from the SCI will hit the asteroid, while the charge case/control system will fragment into space.


I dont have a space background, but i do have Shaped-Charge knowledge to comment somewhat. IMO the charge is large enough to do damage. In oilfield applications, a 0.025kg charge can punch a hole through ~13-45" of concrete or 4-9" of steel depending on type of charge and materials of liner. For reference, the SCI used on Hayabusa 2 is a 10lb (4.5kg) explosive with a 5.5lb (2.5kg) liner.

The use of copper (vs a denser material), as well as the demonstration video would point towards using an EFP. Think of it as shooting a 5lb bullet/missile at the asteroid at 2000m/s. It is going to do something.

The documentation/papers keep saying shaped charge (SC), an interesting question that i have is if they are actually using an EFP (explosively formed projectile). Larger applications (mainly military) work more like EFPs. In vary broad terms, the biggest difference is the angle of the liner (SC < 90, EFP > 90). The two function fundamentally differently however. The SC creates a high velocity 'jet' that stretches and can create a smaller diameter hole in a steel plate 150%-700% ID of charge (with the upper range being denser materials like high-%-tungsten). EFP's on the other hand basically reshape the metal liner to form a large fast moving bullet/warhead- these are MUCH slower, but make a less deep but broader impact.

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pandaneko
post Apr 25 2018, 12:47 AM
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Thank you, caotico09, for the document and your comments particularly towards the last.
My take now then is that the copper plate momentum, much of it, will come largely from its velocity
and I am happierr with that thought. 15kg must be a lot heavier than the plate.

By the way, I saw somewhere, a high speed camera photo of the shape of the copper plate in flight.
It looked very much like a cylindrical Chinese dumpling.

P
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Explorer1
post Apr 25 2018, 02:15 AM
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The crater diameter should be determined much more easily than Deep Impact (any prize for most accurate guess?)
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pandaneko
post Apr 25 2018, 02:50 AM
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What followd is the test firiing range movie.

https://youtu.be/lWnl_G3_N1Y

P
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monty python
post Apr 25 2018, 04:10 AM
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The hole created could be fairly deep too!
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nprev
post Apr 25 2018, 10:50 PM
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Wow! That is a LOT more powerful than I'd expected! ohmy.gif


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Phil Stooke
post Apr 28 2018, 03:16 AM
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174000 km today! We are still sneaking up on Ryugu. I don't know when the first resolved image will be taken, but probably in the next couple of weeks or so.

Phil


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pandaneko
post Apr 29 2018, 01:55 AM
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Tokyo to London is 12 hours, so Hayabusa 2 is half the speed of an international flight, landing gear is not out yet, it is slow, very...

P
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pandaneko
post Apr 30 2018, 06:08 AM
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I have noticed something else on the main page of Hayabusa 2.

Marked with an yellow square is , apparently, the delay time in outbound/inbound
flight. As of today, it is 1941 seconds. What does it mean?

P
Attached thumbnail(s)
Attached Image
 
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charborob
post Apr 30 2018, 10:39 AM
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QUOTE (pandaneko @ Apr 30 2018, 02:08 AM) *
I have noticed something else on the main page of Hayabusa 2.

Marked with an yellow square is , apparently, the delay time in outbound/inbound
flight. As of today, it is 1941 seconds. What does it mean?

P

It means the time it takes for electromagnetic waves to make the round trip from Earth to Hayabusa 2 and back.
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Phil Stooke
post May 9 2018, 07:40 PM
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Schedule of mission events at the asteroid:

http://www.hayabusa2.jaxa.jp/topics/mission_schedule_e/

Phil


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PaulH51
post May 10 2018, 10:19 AM
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QUOTE (Phil Stooke @ May 10 2018, 03:40 AM) *
Schedule of mission events at the asteroid:

Cool list of activities, sounds like a lot of interesting events... Wishing them the best of luck smile.gif


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