Mission: Hayabusa 2 Options

[spdf]

JAXA wants to continue with Hayabusa 2. However there is/was a huge fight about the budget. Main problem was the budget for the launch vehicle. 2 months ago or so there was a report which said, that JAXA had to find another launch vehicle or the project gets cancelled. Now the Italian space agency played saviour and overed the VEGA. So finally we might see another Hayabusa in 2011.


It was mentioned here:
http://www.jspec.jaxa.jp/080110Final_IPEWG-ProgramBook.pdf

[Explorer1]

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.

[pandaneko]

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

[pandaneko]

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

[pandaneko]

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.