Nozomi in perspective, Revisiting the causes of failure Options

[pandaneko]

http://www.mext.go.jp/b_menu/shingi/uchuu/...ts/04061101.pdf

Above pdf file will be translated for aspiring students in aeronautics, control engineering etc. so that in future lay people like me will be able to enjoy planetary scenes and events without worrying about failures.

The overall title is "Looking into the causes of failure and trying to find the right measures to take for the future with respect to the 18th scientific satellite (PLANET-B ) not inserted into Mars orbit as planned" and it is dated 21 May 2004.

This file is very much detailed at 1.1 megabytes and the number of pages is about 40, I think. In addition, I will be translating 3 more files after this particular file. They will be;

1. ISAS file with views and comments on the failure
2. Another ISAS file, a newsletter written out in a series of 4 individual letters.
3. JAXA file, which is a press release and it is a very concise document with just sufficient details.

Re concise link making I tried a few times, but I simply failed and all the links will be fully pasted out as required.

Pandaneko

[pandaneko]

http://www.mext.go.jp/b_menu/shingi/uchuu/...ts/04061101.pdf

above for ease of reference

page 75

Table IV-2-2 Means for seperating out failure causes and their characteristics

(This is a C3R6 regular matrix inluding the headers in row 1)

C1R1: Failure cause seperation means
C2R1: Meritts
C3R1: Demeritts

C1R2: Resistances
C1R3: Fuses
C1R4: Relays and limtter circuits
C1R5: FET switches and limitter circuits
C1R6: Ideal redundancies

C2R2: system is easy and repetitive activations are possible.

C2R3: Setting up is easy.

C2R4: Repetitive activations are possible.

also, cancelling of latching up is possible.

There is a possibility to save components from temporary shortciruiting.

C2R5: Repetitive activation is possible.

There is no limit to the number of activation.

also, cancelling of latching up is possible. There is a possibility to save components from temporary shortciruiting.

It is very easy to set the system to OFF side without fail at the time of power on.

C2R6: It is possible to accept, at least once and perfectly as well, every possible failure mode.

C3R2: Need heat resistance at times of short circuiting.

Given voltage drop we may find it difficutlt to use this as "load current" may fluctuate.

C3R3: Once activated it will remain in the same state forever.

We need to check anti-vivration characteristics at launch times.

Action possible region is generally fairly narrow in that it will function without being affected by a sudden surge etc, with a current which will not affect other devices.

C3R4: Composition is very complex.

Relaying system itself needs watching out for failures and there is a limitation on the number of possible actions that can be taken.

If the relay system is of a "latch type" it may not improve the situation if:

1. there is another breaker downstream and
2. response speed upstream is slow

C3R5: Composition is very complex.

We need to allow for:

1. some extent of voltage drop
2. some extent of heat generation

C3R6: Impact on heavy resources is largest (I have no idea what they are talking about, P)

If we want to introduce cross-redundancies it will lead to the system getting very complicated and we will have to be extremely careful in design and verification.

We will need to evaluate its usefulness against the failure rate of similar redundant systems if:

1. the vulnerability against failure is very localised and/or

2. if the failure rate in question is very low in the first place.

end of page 75

P

[pandaneko]

What follows is the URL of the press release of JAXA on Nozomi's failure.

http://www.jaxa.jp/press/2003/12/20031210_nozomi_j.html

About this coding business I have been thinking about it for the last three weeks. Simplest would be to experiment. Here, I will switch on my hardware switch to write "1 A" using 16 bits coding. What goes before that is "1 A" with 8 bits coding.

1. 1 A with 8 bits coding: 1 A

2. 1 A with 16 bits coding: １　Ａ

With 2. above, I actually added one space with 16 bits coding and that may complicate this issue, but not by much, I hope...

If you can read them both without any problems, then I can forget about my worries about this, except that there might still be cases where the person(s) who wrote the whole thing may have used the mixture of 8 and 16 bits codings without consistency.

This is not a small matter of concern. On placing mail orders, for example, your order may be rejected. It does happen, here, often...

Pandanakeo

[pandaneko]

What follows is the URL of the ISAS pages I am about to ranslate for some time to come.

http://www.isas.jaxa.jp/j/enterp/missions/...status_01.shtml

Its rough title is something like "what Nozomi may have left for the success of future international planetary missions".

This is entirely in accordance with the purpose of my translating relevant files for the advancment of future missions and I am very pleased that I found this particular file for the communities with interest.

Translations will follow shortly. The original file consists of 4 contributions made by the same person and each may take up to a few times of translation. I will not be identifying the name of the person who wrote these pages.

P

[pandaneko]

What follows is the URL of the ISAS pages I am about to ranslate for some time to come.

http://www.isas.jaxa.jp/j/enterp/missions/...status_01.shtml

Its rough title is something like "what Nozomi may have left for the success of future international planetary missions".

This is entirely in accordance with the purpose of my translating relevant files for the advancment of future missions and I am very pleased that I found this particular file for the communities with interest.

Translations will follow shortly. The original file consists of 4 contributions made by the same person and each may take up to a few times of translation. I will not be identifying the name of the person who wrote these pages.

P

In what follows I am translating this document chunk by chunk as I see fit for the purpose because there are no page numbers as such.

Nozomi left the Earth on 4 July 1998 and travelled across the solar system for over 5 years carrying signatures of hope from more than 270,000 people. I regret to say that we had to teminate the operation of Nozomi at 20:30 on 9 December 2003 (Tuesday) despite the frantic efforts by the team upon confirmation that we had not been able to fix the faulty portions of the system.

Consequently, we kept sending out a command to Nozomi from 20:45 until 21:23 on the same day in order to reduce the possibility of Nozomi colliding with Mars. As a result, Nozomi passed, on 14 December, the height of about 1000 km from the surface of Mars and left the gravitational field of Mars to continue its journey across the solar system once again.

Nozomi, the first of its kind ever launched by Japan, has encountered all kinds of difficulties over the last 5 years as had been expected, had to terminate her mission within the last few steps from her success.

Granted that Nozomi, as Japan's first planetary mission, was not able to achieve the maturity as is now taken for granted in other areas such as X-ray astronomy and space plasma physics we nevertheless think that the lessons learnt from operating this spacecraft in the frenzies of it all during the last 5 years must be told to the rest of the world so that our future planetary missions will benefit from the difficulties Nozomi encountered.

I believe that it is the duty of our group to do just that. We were endowed with the resources for that purpose. We must reflect upon failures. That is the only way foward. Both US and Soviet Union have sent more than 30 spacecrafts to Mars to date and 20 of them have failed. (Is this really, really true?, I doubt it, P) We will have to learn from failures. That is the only way forward.

Learn from successes, ride over the faults we found, it is not regrets, not masochistic either, at all, and we can only do forward looking investigations for the humanity.

P

[pandaneko]

Learn from successes, ride over the faults we found, it is not regrets, not masochistic either, at all, and we can only do forward looking investigations for the humanity.

One chunck after above just before two graphs is as follows.

1．On the subject of engineering aspects

There are 4 Japanese spacecrafts which have left the Earth gravitational fields. The first one is the Halley probes, Sakigake and Suisei launched in 1985, then Nozomi, and Hayabusa which is the latest departing in May 2003. However, of all these, Nozomi is the only one which specifically targetted a planet as its destination.

Given limited human resources and finance, very tight scheduling it has been a very challenging task to try and reach a planet. It has been fun, too, of course, with all those technologies to prove in orbit.

First of all, we had this mission analysis. We have gained quite a lot from trying to trade off an innumerable number of engineering aspects in an effort to obtain the maximum benefit from an optimum flight scenario for Nozomi.

I think we have secured the solid foundation for orbital desine and operation technologies, in addition to the experience gained during the flight of Hiten which was launched in 1990, making use of swing-bys with the Earth and the Moon.

Needless to say that we were all very much encouraged and impressed by the frantic efforts shown by this "Orbit and Mission" team, sacrifysing the period non-stop, from Christmass through to the new year period in the face of fuel depletion in the wake of the Earth swing-by in 1998. The heroic dedication that they showed in coming up with a renewed mission plan was a ray of hope for the Japanese space science and technologies.

End of this chunck and this is followed by schematics. I am unsure as to what I might do about them, yet. P