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Mission: Hayabusa 2
Paolo
post Jan 3 2013, 04:47 PM
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thank you for your translation, pandaneko, as usual
can you share the link to the document you are translating?
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centsworth_II
post Jan 3 2013, 09:37 PM
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From "Small carry-on impactor of Hayabusa2 mission"

A schematic of the shaped charge penetrator, a model, and a test impact.

More pictures at the link.


Attached Image


EDIT: The model pictured above is captioned: "Small model of the explosive part. Weight of the explosive is about 150 g." The schematic below is captioned: "Shape of explosive part. It has a liner face in the shape of a shallow dish. The weight of the explosive is about 4.5 kg." So it seems the actual impactor will have 30 times the explosive as the model.

Attached Image
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pandaneko
post Jan 4 2013, 02:14 AM
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Quote removed - Mod


Thank you very much for this. I am particularly grateful because I now seem unable to access the original source file. It was:

http://ae86.eng.isas.jaxa.jp/sss12/paper/s...20202232209.pdf and when I try it I am refused access and one of the advices given is the cache file below, but it does not carry pictures and schematics.

http://webcache.googleusercontent.com/sear...20202232346.pdf

However, I pasted texts into my memo pad. I think some of these are still useful without picture reference and I will try to translate them this evening. In any event "centsworth_II" information is sufficient for us to understand impact operation, I think.

P
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pandaneko
post Jan 4 2013, 07:48 AM
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Quote removed - Mod

This, actually is far better than the pictures and schematics carried in the document I was using. For instance, All I could find as the liner shape was a simple vertical line because only a cross section schematic was there in the document I was translating. Here, you can see a lot more.

Anyway, I have been yapping about this mid spce explosion for a long time, thinking that such an explosion cannot possibly send the colliding mass in the right and accurate direction. I am now a lot happier.

In case anybody is interested I am pasting the remaining pages of translation as follows. P

P-7
Page title: Collision operation

Outline:

1.Mothership descends to the asteroid with the collision device pointing to the asteroid
2.Seperation at an altitude of approx. 500m
3.Horizontal evacuation maneuver
4.DCAM seperation
5.Vertical evacuation maneuver
6.Detonation. Timing is by a pre-set timer. Timer is activated on detecting seperation.

P-8
Page title: Evacuation time

Time between seperation and detonation:

If too short then delta V required for evacuation will get larger. If too long the error in colliding position will get larger,
making the collision point area lager and/or fall to the asteroid before detonation

(I remember there was a couple of pictures here, P)

P-9
Page title: Evacuation maneuver and collision accuracy

Time from seperation to detonation: 2400 seconds, collision point accuracy (radius) of approx. 200m, evacuation delta V is approx. 10m/s


P-10
Page title: Explosive section:

Shape: conical
Liner: Copper without oxygeon
Explosive charge: HMX type PBX
Mass: Approx. 9kg (explosive charge alone is 4.5kg)

P-11
Page title: Liner flight

Liner shape: Shell type.
Deformation time: < 0.5ms
Relative collision velocity: > 2000m/s.
Mass: > 2kg.

P-12

Liner into sand experiment

P-13

1/2 scale model tests

P-14

1/2 scale model flight tests (continued)


P-15

1/2 scale model flight tests (continued)

P-16
Page title: Long flight tests

Test flight distance of approx. 100m

P-17
Page title: Long flight tests (continuation)

Collision body : 1/1 scale model was used and it was confirmed that its intended flight shape was
successfully formed by explosion

P-18
Page title: Long flight tests (continuation)

Deviation from designed flight path of less than 1 degree confirmed, velocity also confirmed

P-19
Page title: Long flight tests (continuation)

Observation of ejecta was carried out

P-20
Page title: Summary

Designed results confirmed and further improvements will be made.
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pandaneko
post Jan 28 2013, 08:21 AM
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Below is just for your information.

March edition of Scientific American (Japanese version) apparently gives the names of those involved in Hayabusa 2 as follows.

Project manager is Prof Hitoshi Kuninaka of JAXA (ISAS).
Project scientist is Prof Seiichiro Watanabe of Nagoya University. His main interest is planet formation.
Mission manager is Prof Makoto Yoshikawa of JAXA (ISAS and National Astronomical Observatory)

P
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pandaneko
post Jan 29 2013, 11:41 AM
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On my way back from a gym session I walked into a library and amazingly found the March edition of this Scientific American!

There was a short article in it with some photos. Photos apart, what caught my eyes were:

1. There will be a small camera to televise the moment of crater creation.
2. There will be 4 reaction wheels (instead of 3 on Hayabusa), all supposedly trouble free because JAXA now know what went wrong with Hayabusa reaction wheels.
3. Improved (on Akatsuki's) chemical engines.
4. More powerful (+ 20%) ion engines.

P
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MahFL
post Jan 29 2013, 12:27 PM
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Is the reason for the reaction wheels failure available to the public ?
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pandaneko
post Jan 30 2013, 08:31 AM
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QUOTE (MahFL @ Jan 29 2013, 09:27 PM) *
Is the reason for the reaction wheels failure available to the public ?


I have no idea and the article did not mention the reason. If there are JAXA reports on this issue I am sure there are reasons given there, but finding those reports is a big problem, I think. By the way, Hayabusa 2 will definitely go in 2014 as the funding has been secured. There have been many newspaper reports on this.

P
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Blue Sky
post Feb 7 2013, 08:55 PM
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Ah, so the explosive device is not "fired" at the asteroid, so there would be no kick-back. The main vehicle starts moving toward the target, releases the impactor, and then moves away, leaving the impactor to continue on toward the asteroid.

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pandaneko
post Mar 19 2013, 08:41 AM
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What follows is from MSN-Sankei newspaper dated 07:58 (local) on 18th March 2013.

JAXA announced that they will use part of the contributions from the general public (approx. JPY 20.000.000) for the flight of Hayabusa 2 in order to install an additional camera at the bottom of the main body so that sampling process can be viewed from the earth.

P

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Explorer1
post Mar 19 2013, 05:01 PM
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Wow! Now that's dedication to PR!
Yes, it's not entirely unprecedented (Junocam, etc.), but seeing such support for outreach is very reassuring.
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centsworth_II
post Mar 19 2013, 06:55 PM
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Most impressive to see that outreach in this case is a two way street. Public donations used for a high public interest instrument. Similar to the Planetary Society's Mars Microphone. I have a feeling (hope) that the camera will be a more integrated instrument that will actually be used as opposed to the microphone which was more like a hitchhiker that mission planners were reluctant to turn on.
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nprev
post Mar 19 2013, 10:03 PM
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Impressive outreach indeed, but let's be careful when analyzing the reasons why instruments are included or omitted. Integration is sometimes more art than science; designers are wary of add-ons, and rightly so.


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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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Astro0
post Apr 8 2013, 03:03 AM
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Hayabusa 2 Name and Message Campaign

http://www.jaxa.jp/press/2013/03/20130329_hayabusa2_e.html
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monty python
post Apr 8 2013, 05:32 AM
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I love these send your name things. I can show support and almost be immortal. GO JAXA!
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