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".

I have had a look again at what I undertook in terms of translation re Nozomi. Part 4, the last part of the ISAS newsletter 4 part series, happens to be all about 15 instruments on board. I was in two minds as to whether I should translate them.

The biggest reason, of course, is that it now seems silly and useless to translate what all these instruments may have performed simply because the whole thing blew up (excuse me here because I had had only a very quick glance at that time when I undertook to translate this 4 part series and I was not aware exactly what the last part of this series contained!).

However, having translated the main text of this series and finding myself being in full sympathy with the author, I will continue to finish translating what remains in the series. It is only a few evenings work! This will come after my translation of another ISAS newsletter for this evening which effectively contains an ISAS version of Nozomi failure press release, as follows.

Nozomi made swing-bys by the Moon on 24 August and 8 December 1998. On 20 December Nozomi made another swing-by with the Earth at a distance of 1000 km, but Nozomi developped an insufficient propulsion due to the the mulfunction of its thruster valve.

Flight course was corrected, but this led to an over-use of the fuel and it became impossible to insert Nozomi into the Mars transfer orbit. For that reason, the arrival timing was delayed from October 1999 to January 2004.

Nozomi was placed into an orbit, after the Earth swing-bys in December 2002 and June 2003, which would have directed Nozomi towards Mars. However, Nozomi developped another mulfunction with the comms. and thermal control system in April 2003 and franctic efforts on the ground could not recover these difficulties.

A command was sent out on 9 December to change its orbit in order to ensure that Nozomi would not collide with Mars for fear of contamination of the planet in accordance with an international agreenment.

P