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 quick reference

page 5

(What is immediately after this is the continuation from page 4. I am sticking to the original layout so as not to create confusion to those who may attempt their own translation)

It has higer efficiency compared with the weight of the fuel required. For your information this method of propulsion is one of the targets for testing with Hayabusa spacecraft which was launched in May 2003.


(4) Nozomi design philosophy


Nozomi design is based on the following considerations.

① We pay utmost attention to reducing the weight of the satellite.

② Since there are instruments which are very susceptible to surface (electrical) potential we should take an even more precaution in earthing them compared with usual measures taken for preventing accidnets due to charging and discharging.

③ We should have a certain criteria/standard for the electromagnetic noise leve so as not to affect instruments on board.


④ We should not use potting materials in order to prevent instrument deterioration through resulting contamination. In order to put into effect the point 1 above following improvements were made.


・With these science satellites we are expected to obtain world top class results and for this reason it will be desirable to keep as much ratio by weight of the instruments against the total weight of the satellite. Therefore, while retaining the reliablity standard comparable to that enjoyed by other earlier satelllites the results of the STRAIGHT project (note 5) were put into use with Nozomi. These included surface mounting of parts, batteries using nickel/hydrogen cells, semiconductor data recorder using large capacity memories etc.


・While the satellite was made as light as possible reliability assurance was of paramount importance and for this reason a redundant system was employed around the CPU relating to attitude and orbit control (AOCE). For your information the bus system design gave a higher priority to weight reduction rather than fault seperation ability given that the system used radiation tolerant parts and other parts for space use, all pointing to much lower possibility of mulfunctiioning.


・ Compared with the earlier central power distribution method a dispersed power distribution method was employed for the first time with a science satellite (17 lines).


・With the observation system a radical reduction in weight was pursued by taking into account the relative merits in reliability against on board weight and this included, for instance, a unified electronic control looking after more than one instrument.

(Note 5) STRAIGHT: Study on the Reduction of Advanced Instrument Weight

This is a project looking into the next generation probe technologies.

end of page 5

P