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 21

5) Defreezing of the fuel tank and RCS thrusters

By the end of August 2002 thanks to the self generation of heat by on-board devices, distance to the sun, and improvements in the satellite attitude part of the propulsion system had been defrozen and in the upper part of September of the same year it became possible to control attitude and try small scale orbital control.

It has been confirmed since then that maintaining of the correct attitude helped to keep the fuel tank, attitude and orbital control thrusters from freezing. Owing to this recovery of attitude and orbital control thrusters we managed to succeed in the 1st Earth swingby operation on 20 December 2002, and also in the 2nd Earth swingby on 19 June 2003.

However, it was also confirmd that recovery of heater function was absolutely vital in defreezing the main thruster (required for orbital insertion around Mars) which was always on the shade side.


6) Recovery operation (operation for recovery of , P) CI-PSU and heater control function

Given that for orbital insertion it was vital to have CI-PSU and heating function back to normal we checked through the gournd tests that a continuous and rapidly-issued series of commands for CI-PSU recovery will not lead to action anomally by CI-PSU.

Based on this we started on 5 July 2003 to issue continuous ON-commands for CI-PSU so as to burn out the troublesome short circuited line on the secondary side. During this operatioh we managed to lose beacon waves. This recovery operation continued until 9 December 2003 without success. We therefore gave up the hope for orbital insertion.

7) Items confirmed through this recovery operation

Following the recovery operation explained as from 1) to 6) above we were able to confirm:

①DHUand CMD were operational normally.

②CI-PSU cannot be made to be ON.

③We cannot switch between telemetry and beacon modes.

④Loss of heating function led to fuel freezing and attitude control could not be achieved.

⑤Primary power supply voltage to CI-PSU was normal.

⑥CI-PSU can provide secondary voltage for a short time only.

From these reasons it was thought that CI-PSU was likely to be healthy and that with a high probability the short circuiting on the secondary device side led to the activation of the over-current protection mechanism, which in turn led to the OFF state of the power supply.

end of page 21

P