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Mission: Hayabusa 2
Blue Sky
post Jun 28 2012, 11:42 PM
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Here is a short article from the English edition of Asahi Shimbun, dated June 9:
Engineers seek smoother space journey for Hayabusa 2
NEC is the prime contractor again.

It seems to me the trouble with "hiding behind" the asteroid when the explosion goes off is that a lot of debris will be floating about for a while.
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Explorer1
post Jun 29 2012, 12:51 AM
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Why would it? The asteroid's gravity is too negligible to hold onto anything and without air resistance, all the particles would fly away at whatever speed the explosion flung them.
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pandaneko
post Jul 2 2012, 09:13 AM
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QUOTE (Explorer1 @ Jun 29 2012, 09:51 AM) *
Why would it? The asteroid's gravity is too negligible to hold onto anything and without air resistance, all the particles would fly away at whatever speed the explosion flung them.


I am not exactly sure what they have in mind. Explosion is isotopic, and to get a maximum directionality push you need an infinite mass sitting behind the explosion, resembling rather like a Chinese frying pan. If you want more then you are talking about a cannon, I think. If you reverse the whole setup you will then get a missile.

In either case they do talk about explosions. So, what are they talking about?

P
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Explorer1
post Jul 2 2012, 08:54 PM
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Seems to me like the goal is both replicating Deep Impact but on an inert body instead of out-gassing comet. This includes staying in the vicinity rather than just a flyby, so as to measure the velocity change easier.
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pandaneko
post Jul 5 2012, 08:03 AM
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QUOTE (Explorer1 @ Jul 3 2012, 05:54 AM) *
Seems to me like the goal is both replicating Deep Impact but on an inert body instead of out-gassing comet. This includes staying in the vicinity rather than just a flyby, so as to measure the velocity change easier.


I realise that I have been putting all this very badly indeed.

First of all, there is no mistake in my translation about "explosion". They did say "explosion" in mid space.

My question/comment is this.

Mid space explosion cannot possibly direct a collidinng mass into the right direction. Neither will it be able to give it a sufficient kinetic energy to dig a hole in the asteroid.

So, what kind of explosion are they talking about? Perhaps, the collidinng mass has an explosive charge to detonate even if incorrectly pointed (as long as it does get tothe asteroid surface?).

P
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pandaneko
post Sep 18 2012, 09:58 AM
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QUOTE (Hungry4info @ Aug 7 2010, 05:49 AM) *
Some diagrams and what-not.


There was a brief TV news coverage on Hayabusa 2 on NHK here yesterday. It said that in order to accelerate the development of Hayabusa 2 a new project manager was appointed. He is Prof Hitoshi Kuninaka of JAXA (that is ISAS). He was apparrently responsible for the development of ion engines used on Hayabusa 1.

Prof Makoto Yoshikawa of NAO (National Astronomical Observatory) is no longer the PM for Hayabusa 2 ? In any event the news also said that fabrication of Hayabusa 2 components is progressing rapidly in time for sending it out in December 2014.

The TV also showed the impact simulation, very briefly, 2 ,3 seconds. There was a clear and large fireball in mid air (it did look like an explostion, not a firing of a projectile) , and also an explosive impact on the asteroid surface. I am not sure if there was a time lapse between them as the video was so brief. I am more and more confused by this...

P
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Blue Sky
post Sep 18 2012, 12:10 PM
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Is Prof. Kawaguchi involved in Hayabusa-2 at all?
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pandaneko
post Sep 19 2012, 11:30 AM
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QUOTE (Blue Sky @ Sep 18 2012, 09:10 PM) *
Is Prof. Kawaguchi involved in Hayabusa-2 at all?


Good question and I am even more confused by all this. My Google alert today (local Kyodo Tsushin, a news provider like AFP), I think, gave me an e-mail (2012/09/15 16:56) and it says Hayabusa 2 is progressing steadily under the direction of Prof Makoto Yoshikawa. My earlier posting was based on the NHK news which I saw on 17 September.

Since I am not exactly sure about the difference between PI and PM both of them may still be involed, but probably not Prof Kawaguchi.

This Google alert of 15 September also gave me a clue to what I had been wondering about. It says that a mass (not an explosive mass) will collide with the asteroid by the force of an explosion. This may be in line with the simulation video I saw.

There was a fireball in mid-air and it was spherical in shape. The explosion on the ground was hemispherical. This, to me, seems like a very inefficient of digging a hole in the crater. Perhaps, there is a very good reason?

P
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Paolo
post Dec 27 2012, 09:03 AM
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Hayabusa 2's structure complete http://www.jaxa.jp/projects/sat/hayabusa2/...What%27s+New%29


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

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elakdawalla
post Dec 28 2012, 03:39 AM
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That's great news. I wish JAXA posted higher-res versions of their photos with their articles....


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Paolo
post Dec 29 2012, 08:57 AM
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high resolution pics are on JAXA digital archive
http://jda.jaxa.jp/category_p.php?lang=e&a...mp;page_pics=50


--------------------
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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pandaneko
post Dec 31 2012, 06:51 AM
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QUOTE (Paolo @ Dec 29 2012, 05:57 PM) *
high resolution pics are on JAXA digital archive
http://jda.jaxa.jp/category_p.php?lang=e&a...mp;page_pics=50


Thanks, Paolo

I also found an intersting article, which I have translated as follows. Its origin is given at the top of my translation. In it, P stands for pictures and G stands for graphics. Some of these are actually texts and they are too small to be properly recognied, so I have not translated these.

Here it goes, from P

http://news.mynavi.jp/articles/2012/12/28/...usa2/index.html


JAXA demonstrates Hayabusa-2 flight model to the press

On 26 December JAXA displayed the flight model currently under construction at its Sagamihara campus (ISAS campus). It is a succesor to Hayabusa which landed on
an asteroid caIled Itokawa and returned to Earth in June 2010. It was shown to the press at the time when only its main body frame and solar pannells are complete.

P-1: Hayabusa 2 shown here. It looks very different from its final form of completion.
P-2: This a 1/20 scale model. A cylindrical device shown in the middle of its body is the impacter.


Another point of difference is its increased length (or height)

Hayabusa 2 measures 1.0mx1.6mx1.25m and weighs 600kg including fuel. As its predecessor it is intended to carry out a sample return mission. Launch timing of December
2014 is assumed. If successful it will return at the end of 2020.


The model shown this time is the completed body frame with its solar pannels plus dummy weight components. Dummy weights are attached to ensure same weight
and same centre of gravity during the vibration tests currently being conducted.


P-3: Shown from behind the probe. Body and solar pannels are flight ready. Main body is composed of 8 alminium honeycombe pannels (6 outer and 2 inner pannels).
P-4: Holes are meant to hold iron engines. Shown in front is the dummy iron engine weight and fuel tank dummy weight is seen at the end of the hole.


P-5: A pipe like object is seen sticking out. This is a dummy middle gain antenna.
P-6: Seen from the left. 3 solar pannels per one wing are folded and obstructing the view of the side of the main frame.


P-7: The device with an ambrella like object is the sampler horn. This sampler horn also is a flight model. A cylinder shown in front is the sase for Minerba 2
(mini-rover)
P-8: Sampler horn seen from the other side. Since three minerba 2 rovers will be on board there is also another cyliner on this side.


P-9: We could not get the front view of of the main body. Dummy weight of the return capsule is only just shown here.
P-10: The model is placed on the vertical vibration tester. Red cable leading from the probe is for acceleration sensors. In front is the horizontal vibration
test bed.


Main points of difference from Hayabusa are as follows.


G-1: On board device comparison (1)
G-2: On board device comparison (2))


Conspicuous in its external appearance is the two high gain flat antennas in place of the usual parabolic antenna. Of these one is intended as with Hayabusa for X-band
(7-8 GHz) range, but the other one is for Ka band (32 GHz) range to ensure higher comms. speed and to secure higher degree of redundancy.


Vital to the return journey is the fuel efficient iron engines. Same number of four engines will be on board. However, propulsive power of each unit has been
increased from 8mN to 10mN.

New device that attracted our attention is the impacter. This device will accelerate a 2 kg copper collider (liner) to a few km velocity by explosion of an explosive
and collide with the asteroid surface, creating an artificial crater of a few meters in diamter. This will make it possible to sample prestine inner materials not
affected by solar corrosion.

There is no significant change made to the sampler horn. One small change is the nails added to the inner surface of the horn tip in order to increase the amount of
samples. The number of projecter has been increased from 3 to 4. Sample containing room is now divided into 3 sections (previously 2 sections).

With Hayabusa there was only one mini rover called Minerba which faild to land on Itokawa. With Hayabusa 2 there will be three of these of similar size and these will
be collectively called Minerba 2. In addition another small lander called MASCOT developped in Europe will be on board.


Hayabusa was intended for sampling from an S type asteroid. Hayabusa 2 will ber flying to a C type asteroid 1999JU3 where existence of organic materials and water
is expected. As a result observation devices will include a near infrared spectrometer and mid infrared camera. Of these Hayabusa did have a near infrared spectrometer,
but observation range has been changed so that water absorption band can be seen.

Main body frame looks similer in size, but it is longer by 15cm in the height direction. Its weight is also heavier bby 100kg in order to cope with the increased
number of devices.

2 years to launch, no time to loose

Expected launch timing is December 2014, but if JAXA fails to make it next launch timing will be 10 years later, making continuiation the whole project impossdible.

Sample return from type C asteroids will be scientifically significant. However, many of them exist in the main belt between Mars and Jupiter and they are
too far from here and Hayabusa class probes will not be able to cope with the mission. 1999JU3 just happens to be in near earth orbit, making it about the only type C
asteroid.




G-3: With Hayabusa 2 there are 3 points of significance
G-4: Mission scenario is different



G-5: Selection of target asteroid. 1999JU3 has been selected.
G-6: With 1999JU3 we still do not know its exact shape.


Project manager, Prof Hitoshi Kuninaka of JAXA (ISAS) stresses emphatically that they will to stick with the launch in December 2014. Theoretically speaking,
there are windows in June and December of 2015. However, arrival timing of June 2018 cannot be moved and the delayed launch will mean that much harsher operation
of iron engines.





P-11: Hayabusa 2 project manager, Prof Hitoshi Kuninaka. He was in cgarge of iron engines with Hayabusa.

December 2014 launch means 80% operation rate. However, the launch in Decmber 2015 will require 96% operation rate, meaning rest time of only 7 hours per week.
Communication with the earth station alone will require 5 to 6 hours and that means almost limiting conditions in case of troubles.

Right now, Hayabusa 2 is located at the Sgamihara campus of JAXA (ISAS), but very soon after the year end 2012 it will be transported to Tsukuba Space Center
to undergo accoustic tests. It will then be returnd to Sagamihara in mid January 2013 to undergo electricl tests and other component tests. Then, from October
2013 its final configuration will start, to be flight ready by summer 2014.



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TheAnt
post Jan 1 2013, 10:30 AM
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QUOTE (pandaneko @ Dec 31 2012, 07:51 AM) *
I also found an intersting article, which I have translated as follows.....


Thank you for yet another update pandaneko, appreciated. =)
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pandaneko
post Jan 2 2013, 12:49 PM
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QUOTE (pandaneko @ Jul 2 2012, 06:13 PM) *
I am not exactly sure what they have in mind. Explosion is isotopic, and to get a maximum directionality push you need an infinite mass sitting behind the explosion, resembling rather like a Chinese frying pan. If you want more then you are talking about a cannon, I think. If you reverse the whole setup you will then get a missile.

In either case they do talk about explosions. So, what are they talking about?

P



Today, I actually managed to find an answer to this question of mine. It is revealed in a document presented at an annual ISAS conference of almost exactly one year ago. Since it is a short 10 page document I will fully translate it and post it tommorrow, I think.

P
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pandaneko
post Jan 3 2013, 09:28 AM
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Today, I actually managed to find an answer to this question of mine. It is revealed in a document presented at an annual ISAS conference of almost exactly one year ago. Since it is a short 10 page document I will fully translate it and post it tommorrow, I think.

P
[/quote]ause of that

As it turned out this is a 20 page document, and not because of that I have not been able to translate the whole pages. So, I am uploading that has been translated so far, as follows. P

My notation is as follows.

Squares on the original PPT files are designated as S (such as S1, S2 etc) and the diamonds are designated as d (such as d1 and d2 etc).

Title page

Hayabusa 2 collision device (S1-07)

5 January 2011
Hayabusa 2 project - collidding device subsystem
T Saeki (JAXA)

P-1 (page one)
Page title: Hayabusa 2 project

S1: With Hayabusa 2 we intend to create an artificial crater by making a colliding body collide with an asteroid.

S2: We will observe thus created crater and subsequently try to sample soils in the crater.



On this page there are 3 boxes as follows. They correspond to Launch, Re-entry, and Sample analysis. Also,
there are three pictures.

Picture -1 at the top is qualified as :

Remote sensing observation (optical cameras, infra-red spectrometer, LIDAR (distance measurement)) etc
=> investigation of the asteroid characteristics
Asteroid observation from vicinity, small rovers, sampling of surface materials

Picture -2 in the middle is qualified as:

Carrying out the collision operation

Picture -3 down at the bottom is as follows:

Observation of crater formation by cameras and sampling of prestine materials (extra bonus if successful)

P-2
Page title: Hayabusa 2 colliding device

S1: SCI(Small Carry-on Impactor)

S2: Create an artificial crater by a collision process

d1: Acceleration by rocket motors etc will mean longer acceleration distances and neccesitate guidance,
leading to system becoming too complicated.

S3: Use an explosion formed intrusion mass which can be created in a very short time so that the colliding device itself willl not neeed to
control its own attitude and carry out guidance.

d2: Acceleration of a metal object by an explosive charge
d3: Ultra-short time acceleration: (up to 2km/s in 1ms or less)
d4: Less contamination of the soil because explosion itself will not crate the crater
d5: Casing material will fly away by the force of explosion

P-3
Page title: Colliding device configuration (graphics and from left to right, section or areawise)

Re-entry vehicle (pale blue area on the left)
and it includes cameras

Remaining area(s) to the right of the re-entry vehicle depicts the collision device which includes:

A: Seperation mechanism (which, I think, is slightly tinted)

and its collision device interface section contains wired interface, pyros for seperation and seperation connecter spring


B: Collision device body

and this consists of :

B-1: Collision controller which includes:

temp. monitors, heaters, power source circuits, sequensers, seperation detecting sensors, primary batteries, ignition/safety mechaism,
heat controlling materials

B-2: Collision explosive section which contains:

relay explosive (ignition explosive?), main explosive charge and a metal liner

P-4
Page title: Mass etc

S1: Mass: Less than 20kg (including seperation mechanism)
S2: Physical size: 300mm diamter x 300mm height
S3: Location: Z face of the probe (inside the rocket coupling ring)

P-5
Page title: Seperation mechanism

S1: Spin seperation (same as Hayabusa)

d1: Collision device itself is not equipped with an attitude control system. Mothership will direct the device.
d2: Spin will be given becuse of the long time before collision (40 minitues) after seperation to maintain its attitude.

P-6
Page title: Outline of collision operation

S1: Colliding device will scatter small fragments in all directions (with velocities up to a few km/s). In addition, landing on the asteroid surface will mean
soil scattering. For this reason, the probe will hide behind the asteroid immediately after the seperation.

(after this, there are 3 boxes as follows)

Box 1: Debris avoidance operation: Hide behind the asteroid.

Box 2: Avoiding high speed ijecta by hiding behind the asteroid: Hide behind the asteroid.

Box 3: Avoiding low speed ijecta: Keep enough distance from the asteroid if they are doing regular orbital flying. At ultra high altitudes
they will have very small velocities and impact effects will be minimal and the probability of collision itself will be very small.
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