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 20

(5) Grasping events by recovery operation after the mulfunction

Grasping of satellite status, information gathering for the causes of mulfunction, and satellite operation after the mulfunction was carried out as follows.

1) Confirmation of the health of data handling unit (DHU) and command decorder (CMD)

A command was sent from the ground on 28 April 2002 and we succeeded in powering on and off of the X-band transmitter power amplifier (XPA)(XPA is normally ON). From this we concluded that DHU and CMD were operable normally.

2) Grasping probe status by "1 bit comms." using the autonomous function

During early part of May 2002 we managed to obtain probe status through "1 bit comms." using the autonomous function. As will be shown in (4) we discovered that the common power supply (CI-PSU) was in the state of being OFF and also it could not be made to switch into ON mode and that the satellite temp. was far below the freezing point of the fuel on board.


3 Loss of the beacon waves due to the recovery operation of the short circuited portion


This was the operation on 15 May 2002. By sending continuous ON commands to CI-PSU (about 100 times) we tried to burn out the faulty line, but we ended up in losing the beacon waves during this process. We carried out ground tests in order to find out why beacon waves were lost and we estimated that the beacon was made into OFF state because when TCI is started up it also meant that TMX's ON and OFF commands are simultaneously issued leading to erroneous action of TMX relay circuit.

It was also felt possible that the wrong command issued by TCI (such as TMX ON/OFF) in response to the ON command to CI-PSU might lead to TMX going back to ON mode again. Thus, we carried out beacon recovery operation by sending out a series of single ON commands.

4) Recovery of beacon waves

Beacon waves were recovered on 15 July 2002 after sending to CI-PSU a series of single ON commands (about 7,500 times). This confirmed our estimate shown in (3) above. It also became clear that the satellite power (primary power supplied to CI-PSU) was healthy and that CI-PSU were able to supply secondary power at least for a short period of time.

For this reason, it was thought likely that CI-PSU itself was healthy and that the power OFF state was caused by


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the protection circuit against excessive current arising from the short circuiting problem within the secondary devices connected to CI-PSU.

end of page 20

P