Nozomi in perspective, Revisiting the causes of failure |
Nozomi in perspective, Revisiting the causes of failure |
Oct 23 2011, 09:12 AM
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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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Dec 24 2011, 10:19 AM
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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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Jan 17 2012, 10:11 AM
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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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Jan 19 2012, 08:28 AM
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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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Jan 25 2012, 09:47 AM
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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". What follows is the start of the part 2 of this 4 article series. This is immediately followed by the Lyman aplha schematic. 2.About science observations Nozomi had in total 15 different means of observing the Mars. Following the trouble with the Earth swing-by in 1998 and the period following it for 5 years in wait mode with Sun-centric orbits we made a lot of scientific observations, mostly to check up on the health of the instruments on board, and some of these included very unique observations. Mars camera (MIC) sent us a two-shot view of the Earth and the Moon in July 1998. This particular photograph did not have any value to professionals and exterts at all, but once it was carried on newspapers it brought in a lot of emotional responses from the general public. It is a kind of " memorial snap shot" of friendly planets, all travelling in the vast expanse of the universe. Also, Nozomi became the first space probe sent by Japan to have a look at the other side of the Moon for the very first time in history. Nozomi's ultraviolet spectrographic camera made measurements on the hydrogen Lyman alpha line in the interplanetary space. Hydrogen Lyman alpha radiation from the Sun is scattered by the neutral hydrogen atoms floating in the interplanetary space and lights up the space. It reminds us of the fact that the air-molecules surrounding the Earth scatter the solar ray, producing the beautiful blue sky for us. Where do all these hydrogen atoms come from? They originate in the material flow called "interplanetary wind" in our galactic system. This interplanetary wind, as it approaches the Sun, is ionised by the energy of the solar wind and the ultraviolot component of the Sun's radiation. Thes ionised hydrogen atoms will no longer scatter hydrogen Lyman alpha light and the less condensed, by ionisation, interplanetary wind will continue its travel downstream. It is for this reason that the Lyman alpha light looks stronger in the direction from which it is coming and darker in the opposite direction. From the observation made by Nozomi of the hydrogen Lyman alpha light distribution and its intensity in the interplanetary space we are trying to study the properties of the Solar wind causing all these changes. End of this particular chunk. P |
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