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 I made some omissions about redundancies with onboard computers in the last page. The passage should have read;

the systems around CPU relating to data handling unit (DHU) and AOCE adopted "waiting" redundancy and the register for the common systems had a tripple redundancy incorporated in the system

("waiting" bit, I am unsure. I just simply translated direct from the original sentence, P)

page 6

From the viewpoint of point ② above all of the layers of the thermal blanckets (MLI) well over 100cm in length were earthed. In addition, conducting treatment to the cover glass of the solar cells and earthing were carried out. We also adopted approapriate design for keeping the instruments full capacity as outlined in ③ and ④ above.




(5) Further weight reduction due to launch postponement

Nozomi's launch date was sifted due to the delay in M-V development. It was decided in 1994 that the launch will be postponed to 1999. The most desirable launch timing was 1997 from the perspective of the satellite weight. The new launch timing of 1999 meant that the weight will increase by 30kg, coming from the fuel and this immediately meant that the dry weight of the satellite will have to de reduced by a further 20kg from the original design (10kg was to be covered by the increased rocket capacity).

Given all these we decided that an alteration to the then adopted shape of Nozomi and total reconsideration of the insturment layout was too risky at this stage and that the two years arising from the delay will have to be used to come up with further reduction in weight of individual components without changing the interface with other parts.

One such example includes the power supply to the heater control circuit (HCE) and data recorder (DR). Originally, the power to these was to be supplied from a dedicated source. However, they consumed a relatively small amount of power and the source of power was thus changed to the common systems power source (CI-PSU) and the number of power sources itself was also reduced from the original 17 to 15.

Individual weight reductions achieved during this period and their effects are listed on the table I-2-3.



３．Outline of the history of the failure of Mars orbit insertion of Nozomi

(1) Occurrence of mulfunction in the fuel supply system (20 December 1999)

Nozomi was launched on 4 July 1999 from the then ISAS Kagoshima space centre by an M-V 3 rocket. A mulfunction was detected in the fuel supply system during the escape from the earth gravity on 20 December 1999 and Nozomi failed to produce required propulsion. As a result, it became impossible to contemplate an insertion into Mars orbit during the middle of October 2000.

Therefore, it was decided to make use of 2 earth swingbys and reach Mars after a delay of 4 years some time in late December 2003 to early January 2004. This was a further change of plan.

For your information, the orbit plan after this change is shown with the schematic I-3-1.

end of page 6