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

(I realise that I forgot to look at the earlier reference number. I will deal with it seperately.)

page 10

・After the termination of OME burn a close command was sent out following the sequence to liquid and gas system latching valves (LV2, LV5, and LV6) and the indicator showd "closed".

・After this a series of sequence including spin down and attitude change was excecuted without any problem.

2) Mulfunction situation

From these points above the mechanism of insufficient delta V is estimated to be as follows.


① Despite the fact that LV2's indicator is showing open status not enough pusher gas is being supplied to the oxidiser tank. From the relationship between the estimated value of empty tank volume change and and pressure change it is estimated that the supplied amount was 2% of the LV2 complete close case.


②Oxidiser tank pressure decreased.


③ Not enough oxidiser was supplied to OME, leading to an inefficient burn, resulting in OME propulsion drop.


④ Because of this unexpected propulsion drop OME firing was terminated as the maximum burn time was reached before attaining the planned delta V.


3) Where faults took place

Insufficient delta V during TMI was due to the decrease in the capacity to supply pusher gas to the oxidiser tank. Possible cause of this decrease is thought to be hitches relating to the check valve CV2 and the latching valve LV2 in the propulsion system. In this particular case it has been shown that this insufficiently opened passway occurred not with CV2 but with LV2 from the following reasons.

① The pressure value returned to normal as a command was sent out from the ground to open LV2.


② The output of the acceleration meter indicated that there was a shock as the LV2 valve opened and also there was a vibration as the gas flew as a result.


(4) Operation after this and the status of LV2


1) Evaluation of the status of the propulsion system

In order to make up for the insufficient delta V during TMI two additional corrective OME burns (TMI_C1, TMI_C2) were conducted and these were carried out normally. We also carried out an evaluation test on the OME propulsion and supply system in order to check on approapriateness of the corrective burns and subsequent health of the propulsion system and we are satisfied that propulsion system returned to normal.

a) Evaluation of OME propulsive power

We obtained, from the acceleration of OME burn and tank pressures data, OME propulsive power and its specific impulse as well as the amount of propellant flow. These characteristics were then sorted out according to the regulator pressure (P2). The result showed that during the subsystem burn tests (SFT) and during the early stage after the launch TMI_C1 and TMI_C2 both showed almost similar characteristics, meaning that there was no trouble with the OME burns. (Schematic II-1-8)

end of page 10

(actually, part of the very last paragraph spills into page 11, P)