[X] My Assistant

[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

[centsworth_II]

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.



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.

[pandaneko]

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.

[pandaneko]

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

[pandaneko]

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

[MahFL]

Is the reason for the reaction wheels failure available to the public ?