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 76

Table IV-2-3 Concrete examples of failure seperation methods

(Inside the top horizontally oblong square says):

Large characters and those enclosed inside ovals are the points of improvements made with Nozomi

(However, I do not find any large characters on this page and next. There are, however, characters shown in red toegther with lines in red as you will see)

(There are two system outlines on this and next page, one on left and the other on right)

(One on left here says): Nozomi's system outline : current

(the only other characters for translation here is inside the top of 3 boxes next to TCI and it says): "Pressure monitor".

(the other one on right here says): Nozomi's system outline with improvement plan (1): Protective resisters in case of Black Box failure.

(the only other characters for translation here is inside the top of 3 boxes next to TCI and it says): "Pressure monitor".

end of page 76

Page 77 (system outline continuued)

(One on left here says): Nozomi's system outline with improvement plan (2): Protective resisters in addtion to switching between CI and PSU ( as indicated by vertically long square in red) + 1 kg in weight ( and the characters in this square says):

"Power control motherboard (within TCI)"

(the only other characters for translation here is inside the top of 3 boxes next to TCI and it says): "Pressure monitor".

(the other one on right here says): Nozomi's system outline with improvement plan (3): Protective resisters in addition to individual power source for every device (+ 3 kg in weight)

(characters in the square above LVDT next to TCI-2 box in red says): "Pressure monitor".

end of page 77

P

[pandaneko]

end of page 77

I now realise that I have effectively come to the end of translation work for this particular document. There are some more pages including pages 79 to 81 which are glossary pages in English and Japanese and very useful for any future correction work.

However, just glancing at these pages I note with satisfaction that I have not made fatal mistakes in the choice of my wordings.

Other pages are irrelevant to the story of this failure and need not be translated.

For now I may take up to 10 days of break in view of the inevitable events coming up over the next 2 weeks or so. However, it does not mean that I will not be able to grab time to do what remains to be done even during this period. It is just inpredictable.

When I resume the first document will be the JAXA press release summing up the causes of failure.

P

[pandaneko]

When I resume the first document will be the JAXA press release summing up the causes of failure.

What follows is the press release. I will provide link info and any other info later. Also, I am not exactly sure if this will be useful and I may not be able to complete translation of the whole of this release this evening and in which case I will continue tommorrow on with the rest. Here, we go as follows.

About abandoning insertion of Nozomi into Mars circular orbit

10 December 2003, JAXA

We reported on above subject to Space Activities Comission (SAC) held today as follows.

1. Current status

1. Mars probe Nozomi (launched July 1999) (fig. 1) developped a mulfunction in the fuel supply system at the time of leaving the earth gravitational fields (20 December 1999) (mulfunction history shown in seperate paper 1) and we had to change the original orbital plan and the arrival had to be changed from October 2000 to December 2003.


• 1st Japanese Mars probe launched by ISAS, carrying instruments from Sweden, Germany, US and Canada, also in cooperation with France.

• Launched by M-V 3 solid fuel rocket on 4 July 1998 from Uchinoura Space Observation Centre of ISAS in Kagoshima prfecture.


• Main objectives: Interaction between Solar winds and upper utmosphere of Mars

(Martian magnetosphere, atmosphere, plasma composition, satellites)

• Nozomi has been in its final approach into Mars since June of this year. EAT is 14 December.


Fig. 1 Outline of Mars probe Nozomi (Planet


2. A mulfunction developped in April 2002 in the comms. and thermal protection systems, resulting in minimum amount of communication in addition to incapability to perform temperature control. The mulfucntion here refers to thoes events as shown in Fig. 2 whereby part of the series of the circuits meant to supply power from common sources of power to components developped short circuiting.


Fig. 2 Nozomi power supply, schematic outline

3. May 2002 we tried to stablise probe temp. by turning on instruments. Also, we made a restoration work by trying to burn out the short circuiting sections by directing currents. However, this operation resulted in total loss of communiction capability.

4. July 2002 we kept trying to recover comms. for two months based on the findings of trouble shootings and achieved a minimum level of communication capability.

5. August 2002 fuel temp. reached that of fuel defreezing temp. This was due to the decreasing distance between the probe and the Sun and also the heat generated by the instruments on board. From here on we managed to control fuel temp. by keeping the right probe orientation.

6. June 2003 we managed to insert Nozomi, using the bare minimum communication means, into its final transer orbit.

7. July 2003 we needed precise orbital determination and firing of the main engine. This meant that we had to restore thermal contorl system and the work began as required. Unfortunately, this work yet again led to the total loss of comms.

8. From July 2003 to today (December) we have been trying to burn out the short circuiting sections by directing currents to there, and this meant that the number of times we turned on the common power source reached 1.3 times 10,000,000,000.

We also tried to rewrite the ROMs on board in order to exclude the possibility of the onboard computers going bad to no effects. Based on this we returned the ROMs to their initial values and continued with "continous ON" operation, but there is no prospect of recovery on the night of 9 December.


9. All this made us persuade that insertion into Mars orbit was no longer possible and we began the process of work required to make sure Nozomi will avoid collision into Mars on the night of 9 December in accordance with an international agreenment (collision probability is less than 0. 1% as required)

For your reference current orbital plan with insertion in mind is shown in Fig. 3 and that of fly-by is shown in Fig. 4. As you can see from Fig. 3 continuing with the current orbital plan with a fly-by will mean just a slight acceleration by Mars gravity and lead to a clser approach to Mars.


NOTE) COSPAR planetatry protection policy and moral obligation to observe its policy



Fig. 3 Nozoni's original orbit

Fig. 4 Nozomi's Mars orbiting plan and its fly-by orbit


(This will continue, not by very much, though)

P

[pandaneko]

(This will continue, not by very much, though)
P

What follows is the translation of the "seperate paper 1" mentioned in the last entry. I am afraid I cannot paste the URL yet of this report as I do not wish to loose what has been copied for this entry. I will do that tommorrow.

Seperate paper 1

About giving up the hope of inserting Nozomi into Mars circular orbit



History of Nozomi's mulfunctions. Mulfunction of this time

20 December 1998

Escape from Earth gravity to the mulfunction in which not enough propuslive power was achieved


Causes:

Too much fuel had to be used because the valve upstream of the oxidiser tank had not been fully opened (note 1), leading to much less propulsion than expected. The valve in question was what had been specifically employed in order not to allow reverse flow of the fuel and oxidiser vapours upstream as precaution given the US Mars Observer's trouble.


Measures taken:

It was discovered that it was not going to be neccessary to close the above valve in order to stop the reverse flow given the amount of remaining fuel after Earth escape operation. It was therefore decided that we will open the above valve during the visible operational period on 21st and keep it opened during the rest of our operation.

Influences:

We had to give up our originally planned Mars insertion operation due to take place in mid October 1999 and had to delay it until sometime between end December 2003 to early January 2004. (Subsequent orbit optimisation led to the time of arrival to be 14 December 2003.)


26 April 2002: Signal came in as a beacon signal (*1) (trouble at this time)


Causes:

Short circuiting had developped in parts of the secondary circuit of the common system power source (CI-PSU) and it is estimated that this was due to the high energy particles in the wake of the massive solar flares on 22nd (maximum as far as Nozomi was concerned).

Influences:

We were no longer able to send data from Nozomi to the ground because there was no power. In addition, the thermal control circuit was not active. (It was later discovered at the end of April that the fuel had been frozen at the time of 26th.)

Measures taken:

3 May 2002:

We turned on instruments one by one so that satellite temp. could be improved. Thermal analysis told us that the left-alone- attitude operation will lead to natural defreezing in September.

15 May 2002:

We lost beacon wave reception due to continuous sending of "ON commands" to the sections concerned.


• It is thought that the X-band transmitter's relay circuit caused a mulfunction (to OFF) due to the imperfect start-up of the power source for the ICs meant for command distribution. (Both ON and OFF commands were issued at the same time)

• Ground tests showed that different relays will behave differently and this presented the possibility of recovering the beacon communication by issuing a one-off command meant specifically for the power source in question.

Measures taken (before report acceptance?):

15 July 2002:

After some 7500 trials beacon communication was back.

End August 2002:

Fuel defreezing temp. reached -> after this we kept attitude control for this state so that fuel freezing will not occur again.

20 December 2002:

1st Earth swing-by

19 June 2003:

2nd Earth swing-by

Since 5 July 2003:

Short circuit section's burn out operation by keeping CI-PSU permanently ON. During this process total loss of beacon communication on 9 July.

From 2 October 2003 to around 20 October 2003:

Rewriting of the contents of the memory on board in order to exclude the possibility of the mulfunction of the DHU on board (*2)


From 23 October 2003:

Re-starting the operation for burning out the short-circuiting sections by continuosly issuing commands by CI-PSU.


NOTE 1:

Looking into the causes of the valve mulfunction we now know that it is almost certainly due to the increased resistance to the sliding motion at the sliding section due to incompatibility of materials used at that section.


*1

Beacon state: Signals are sent out by the satellite, but no data is carried on these waves.


*2

DHU： the most important computer on board, for evrything.


End of this press release

P