Nozomi in perspective, Revisiting the causes of failure |
Nozomi in perspective, Revisiting the causes of failure |
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#1
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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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#2
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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 75 Table IV-2-2 Means for seperating out failure causes and their characteristics (This is a C3R6 regular matrix inluding the headers in row 1) C1R1: Failure cause seperation means C2R1: Meritts C3R1: Demeritts C1R2: Resistances C1R3: Fuses C1R4: Relays and limtter circuits C1R5: FET switches and limitter circuits C1R6: Ideal redundancies C2R2: system is easy and repetitive activations are possible. C2R3: Setting up is easy. C2R4: Repetitive activations are possible. also, cancelling of latching up is possible. There is a possibility to save components from temporary shortciruiting. C2R5: Repetitive activation is possible. There is no limit to the number of activation. also, cancelling of latching up is possible. There is a possibility to save components from temporary shortciruiting. It is very easy to set the system to OFF side without fail at the time of power on. C2R6: It is possible to accept, at least once and perfectly as well, every possible failure mode. C3R2: Need heat resistance at times of short circuiting. Given voltage drop we may find it difficutlt to use this as "load current" may fluctuate. C3R3: Once activated it will remain in the same state forever. We need to check anti-vivration characteristics at launch times. Action possible region is generally fairly narrow in that it will function without being affected by a sudden surge etc, with a current which will not affect other devices. C3R4: Composition is very complex. Relaying system itself needs watching out for failures and there is a limitation on the number of possible actions that can be taken. If the relay system is of a "latch type" it may not improve the situation if: 1. there is another breaker downstream and 2. response speed upstream is slow C3R5: Composition is very complex. We need to allow for: 1. some extent of voltage drop 2. some extent of heat generation C3R6: Impact on heavy resources is largest (I have no idea what they are talking about, P) If we want to introduce cross-redundancies it will lead to the system getting very complicated and we will have to be extremely careful in design and verification. We will need to evaluate its usefulness against the failure rate of similar redundant systems if: 1. the vulnerability against failure is very localised and/or 2. if the failure rate in question is very low in the first place. end of page 75 P |
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#3
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
What follows is the URL of the press release of JAXA on Nozomi's failure.
http://www.jaxa.jp/press/2003/12/20031210_nozomi_j.html About this coding business I have been thinking about it for the last three weeks. Simplest would be to experiment. Here, I will switch on my hardware switch to write "1 A" using 16 bits coding. What goes before that is "1 A" with 8 bits coding. 1. 1 A with 8 bits coding: 1 A 2. 1 A with 16 bits coding: 1 A With 2. above, I actually added one space with 16 bits coding and that may complicate this issue, but not by much, I hope... If you can read them both without any problems, then I can forget about my worries about this, except that there might still be cases where the person(s) who wrote the whole thing may have used the mixture of 8 and 16 bits codings without consistency. This is not a small matter of concern. On placing mail orders, for example, your order may be rejected. It does happen, here, often... Pandanakeo |
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#4
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
What follows is the URL of the ISAS pages I am about to ranslate for some time to come.
http://www.isas.jaxa.jp/j/enterp/missions/...status_01.shtml Its rough title is something like "what Nozomi may have left for the success of future international planetary missions". This is entirely in accordance with the purpose of my translating relevant files for the advancment of future missions and I am very pleased that I found this particular file for the communities with interest. Translations will follow shortly. The original file consists of 4 contributions made by the same person and each may take up to a few times of translation. I will not be identifying the name of the person who wrote these pages. P |
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#5
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
What follows is the URL of the ISAS pages I am about to ranslate for some time to come. http://www.isas.jaxa.jp/j/enterp/missions/...status_01.shtml Its rough title is something like "what Nozomi may have left for the success of future international planetary missions". Nozomi made observations during the time of the Moon swing-by. This was in order to look into the plasma environment surrounding the Moon. Our Moon absorbs the solar wind which is a flow of plasma from the Sun. However, Nozomi's ISA, Ion particles (maybe, spectrum, P) analyser, detected, for the first time, the plasma which was part of the Solar wind that had been reflected by the front face of the Moon. We examined ion velocities, Moon position, direction of the Solar wind etc in great details and as a result we found that this particular plasma was closely related to the Moon and that it had not been newly formed by the Moon and that it had rather been formed by the reflection of the Solar wind by the Moon. It has been often said, as a result of Apollo landers, that some parts of the Lunar rocks are weakly magnetic and this seems to confirm that the shock waves formed by the Solar wind on colliding with these magnetised rocks are reflecting the Solar wind ions. This would mean that the Solar wind is blocked at the front face of the Moon, leaving a vacuum region at the back with an extremely less plasma density. Nozomi's onboard ESA detected these electrons coming from this vacuum region. It had been predicted that there was to be a potential difference of a few tens of Volts through the mechanism called "bipolar dispersion (best I could translate, P) between the vacuum region and the Solar wind. However, given that the reflected electrons had something like 480 eV, very high indeed, 10 times the predicted value and We may have to accept that. (end of this chunk, P) |
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