Nozomi in perspective, Revisiting the causes of failure |
Nozomi in perspective, Revisiting the causes of failure |
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
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 |
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
above for ease of reference page 18 Ⅲ.About the mulfunctions of comms. and thermal control systems 1. Environment in which mulfunctions took place (1) Outline of the power source system Unlike all other scientific satellites which had adopted a centralised power source Nozomi was the first satellite to use a decentralaised power source. Within the Nozomi power system there were 15 power sources and one of them was the Common Instrument Power Supply Unit (CI-PSU) which was used to supply power to a multiple number of commonly used systems (equivalent to power source 2 in fig. III-1-1). This CI-PSU receives power from solar cells and batteries placed on the primary side and supply power to 10 secondary side subsystems such as the telemetry command interface (TCI) for the X-band transmitter (TMX) and the heat control circuit (HCE). For your information, the structure of CI-PSU is shown by the schematic III-1-2 and the table III-1-1. (2) About the operation from the time of losing signals until the day of mulfunction taking place The mulfunction was first detected during the operation on 25 April 2002 and the location of Nozomi at that time is shown by the schematic III-1-3. Also, the operational sequence from a day earlier (24 April 2002) prior to losing signals until the day of detecting the mulfunction is shown on the schematic III-1-4. This operational sequence tells us the following story. ① At 18:05 on 25 April 2002 (UTC) signals came in in the beacon mode despite the expectation that the transmission mode had changed to the telemetry mode (note 8). We then sent a command from the ground so that the mode changed to the telemetry mode, but this was not successful. From all this it is obvious that the status remaining was such that we could not switch the mode. (note 8) : telemetry mode mode in which telemetry information from the satellite is carried on the satellite wave (note 9) : beacon mode satellite is emitting waves, but these waves are not carrying telemetry information. ② We had anticipated an attitude change (about one degree) at 09:00 on 25 April (UTC). However, from the reception level of the satellite waves on 25 April it is estimated that this attitude change did not take place (fig.19-III-1-5). It is also estimated that the command sent from the ground for the attitude change did not succeed. From all above it is estimated that the attitude change remained impossible. end of page 18 P |
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