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 29


２．About the measures to be taken in future with comms. and thermal control systems

With the mulfunction in comms. and thermal control systems it is difficult to pinpoint single causes of the mulfunction given that as mentioned before it is difficult to be specific about the causality with solar flares and also that thorough measures had been taken with respect to the possibility of discharging in the design of Nozomi.

For this reason the remaining possible mulfunction candidate is the accidental failure of components and measures to be taken in this regard can be as follows. For your information other measures to be taken with respect to the cause candidates which are extremely unlikely to be true given the thorough preparations that had gone into Nozomi's flight are seperately listed on the table IV-2-1.

(1) Responding by seperating out failures

With these interplanetory missions such as one attempted by Nozomi we can gain precious engineering and physical knowledge from the mere fact that the mission existed at all in outer space. For this very reason we should endevour to make sure that we produce a design which will allow continuation of the mission even if some of the on-board devices develop mulfunctions.

With this in mind we then must reduce the number of mulfunction possibilities and even in the event of mulfunction our design should be able to localise its effects and prevent its ripple effect eating into the more superior systems by placing more emphasis on seperating out failure causes.

In this regard in the case of Nozomi we must admit that not enough care had been taken to prevent an initial mulfunction of the component(s) which occurred on the secondary side of CI-PSU system from spreading into the more superior CI-PSU. For your information the method and characteristics of failure separation and some examples are listed on the tables IV-2-2 and IV-2-3.

(2) Development of components which will not cause latch-ups

With latest components it is becoming increasingly difficult to insert protective registers since their current amplitudes are large and allowable voltage bands are narrow. Also, even with those components which have small possibility of latching-up we are still talking about probability of mulfunction and there is no way we can say that they will not fail.



For this reason developments are underway for semiconductor devices such as "silicon on insulator" (SOI).

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We are aware that these devices are being developped for consumer uses. However, we should also try and carry out further research so that these may be used as space flight components.

end of page 29

P