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 13


4) Structure of LV2

LV2 structural outline is shown by the schematic II-2-1. Inside the valve there are 2 electromagnets (one each on the right and left of the schematic) and they activate the inner piece (some kind of intermidiate piece, P).

いての独自の追加試験の検討
By letting an electrical current flow through the close side electromagnet (on the left) the inner piece is pushed in and the flow is stopped (state of the schematic) and by letting an electrical current flow through the open side electromagnet (on the right) the inner piece will leave the plug (or seperate from the plug, P) and in that state there occurs a small pressure difference between the up and down streams and this differential pressure pushes the plug and the flow will start.

Also, as shown on the schematic II-2-1, LVDT on the right will monitor the open/close status of the valve by detecting the position of the inner piece. Those original valves with track records of being used with satellites did not have this LVDT. Design change by adding this LVDT meant that the plug and the inner piece were seperate items.

This arrangement of having a seperate structure had been proposed by the US valve manufacturer in an answer to the concern that the addition of LVDT meant a longer inner piece and a resulting small positional erorr might influence the open/close operation of the valve.

(2) Contents of LV2 verification

1) Verification method for LV2

Starting from valves used for scientific satellites those valves used for space use are almost all imported from overseas. Consequently, verification of the selected valves are carried out by those overseas manufacturers and the Japanese procurers. In the case of Nozomi too, this verification was carried out by both US manufacturer and in Japan as shown below.

a)LV2 verification method

① Contents of verification requested by the Japanese side to the US valve manufacturer

・ Verification of design validity

・ Verification of manufacturing validity concerning the shipped flight items

・ Flight track records

Flight tracking records include, if possible and approapriate, concrete mission names and usage. We regarded the usage as important because if the past programmes' mission duration and environment had been different it might be difficult to count it as a proven track record.

② Contents of verification conducted by the Japanese side

・ Confirmation of the justification of the verification methods for each of the items which relate to the verification of the validity of design and manufacturing

(up until here, translation from page 13, but the circle 2 continues into page 14 as follows, P)

- 14 -

・ Carrying out a consolidated system test in the state in which the items were actually built into the satellite

・ Investigating into the possibility of our own additional tests with those items whose flight tracking records could not be confirmed and where details of the verification methods were not available.

end of page 13

P