Page 5: Film cooling thrust direction anomally FTA

C1B1: Box D2

C2B1: film cooling thrust direction anomally (0-152 s)

C3B1: insufficient fuel supply
C3B2: excessive fuel supply
C3B3: injector apperture anomally

C4B1: insufficient fuel pusher gas pressure
C4B2: excessive pressure damage to fuel liquid system
C4B3: fuel leak from fuel liquid system
C4B4: excessive pressure gas
C4B5: too little pressure damage to fuel liquid system
C4B6: closure by salt formation
C4B7: closure by contamination
C4B8: deformation by errosion

C5B1: bad regulation
C5B2: excessive pressure damage to gas system
C5B3: gas leakage from gas system
C5B4: closure of fuel tank outlet
C5B5: excessive pressure damage to the piping between the tank and port P3
C5B6: excessive pressure damage to the piping between port P3 and the injector

C6B1: clogging of piping system
C6B2: closure of CV-F (Shaded, i.e., suspicious)

C7B1: closure by contamination
C7B2: closure by fuel freezing

The yellow arrow pointing at the connection between C4B1 and C5B1 says that this is the point at which fuel tank pressure P decline is reflected in this FTA

C8VB1: negative: telemetry data for P2 and P4 are normal and both receive gas supply from the same regulator

C8VB2: negative: pre-launch water flow test confirmed the health of pressurising system. Cleanliness test afterward was normal and contamination leading to piping system closure is unthinkable

C8VB3: negative: we cannot deny the possibility of fuel vapour penetrating into the pressurising piping system through the diagphram. However, temp data suggest that there was no such low temp status leading to fuel vapour freeze

C8VB4: possible: we cannot rule out the possibility of mulfunction given specs, test results, and tested items. For more details see CV-F closure FTA

C8VB5: negative: each pressure value for P1, P2, and P3 within the fuel pressurising gas system after VOI-1 was normal

C8VB6: negative: given the estimated amount of remaining fuel the diagphram could not have moved to a position that can cause closure of fuel tank outlet

C8VB7: megative: P3 is supposed to go up to the value of P2 immediately after VOI-1, but in reality it took about one hour. Thus, this is not possible

C8VB8: negative: both acceralation and tank pressure telemetry data since VOI-1 start are in unison

C8VB9: negative: Ditto

C8VB10: negative: P3 was shifted to the value lower than designed and there was no excessive fuel supply

C8VB11: negative: temp data of injectors with orifice and thrust outlet were normal. Expansion of flow channell through errosion etc in unthinkable

C8VB12: negative: ground test confirmed that salt, if formed after test manuevor, will sublimate during the time until VOI-1 (longer than 5 months)

C8VB13: negative: cleanliness test. In addition, there is a filter just upstream. This probability is extremely small

C8VB14: negative: telemetry data of injector temp was within the range confirmed by ground testing and the temp did not reach a temp region which might have caused errosion

Box connection:

1. D2>C2B1>C3B1>C4B1>C5B1>>>C8VB1

2. D2>C2B1>C3B1>C4B1>C5B2>C6B1>C7B1>>> C8VB2

3. D2>C2B1>C3B1>C4B1>C5B2>C6B1>C7B2>>>C8VB3

4. D2>C2B1>C3B1>C4B1>C5B2C6B2>>> C8VB4

5. D2>C2B1>C3B1>C4B1>C5B3>>> C8VB5

6. D2>C2B1>C3B1>C4B2>C5B4>>> C8VB6

7. D2>C2B1>C3B1>C4B2>C5B5>>> C8VB7

8. D2>C2B1>C3B1>C4B2>C5B6>>> C8VB8

9. D2>C2B1>C3B1>C4B3>>> C8VB9

10. D2>C2B1>C3B2>C4B4>>> C8VB10

11. D2>C2B1>C3B2>C4B5>>> C8VB11

12. D2>C2B1>C3B3>C4B6>>> C8VB12

13. D2>C2B1>C3B3>C4B7>>> C8VB13

14. D2>C2B1>C3B3>C4B8>>> C8VB14

P

I have a simple and naive thought...

In order to understand what might have happened to the main thruster nozzle, why can you not install a very simple one-off camera at the corner of the surface where the nozzle is attached? It seems far simpler and I recall MINERVA caught a glimpse of Hayabusa in mid space...

Pandaneko

You mean like on Chang'E 2?
Of course its possible and of course it adds to the cost.
But hopefully more and more missions will be equipped with engineering cameras.
If only for the vicarious experience it gives those of us stuck here on Earth.
Click to view attachment

Exactly! This is just what we need. Re costs, we do not even need a movie camera, just a simple still camera because in a case like this where we wonder if what is ought to be is still really there or not must be a simple matter solved by a still camera instantly.

JAXA must be spending a lot of money on their FTA, how many man housr?, or weeks? And, the result is a guess work, I think. Thanks.

Pandaneko

Page 6: 1.3 Throat rear burn FTA

(let me explain my naming scheme. Columns are from left to right, 1,2, 3 etc, and boxes are from top to bottm, 1,2, 3 etc.

For example, C3B5 means it is the box on the column 3 and 5th box from the top box whereever this top box happens to be. VB means verdict box and naming scheme is the same.

Therefore, even if I made mistakes in the box connection ( and I am being very careful) one should be able to correct for my mistakes in box connection, which is very messy, by referring to the original page.)

C1B1: box D3

C2B1: throat rear burn at 152 s (tree top)

C3B1: insufficient fuel supply
C3B2: excessive fuel supply

C4B1: insufficient fuel pusher gas pressure
C4B2: excessive pressure damage to fuel liquid system
C4B3: fuel leakage outside from fuel liquid system

C5B1: bad regulation
C5B2: excessive pressure damage to gas system
C5B3: gas leakage from gas system
C5B4: closure of fuel tank outlet
C5B5: excessive pressure damage between tank and P3 port
C5B6: excessive pressure damage between Port 3 and injector

C6B1: piping closure
C6B2: closure of CV-F (this box is shaded)

C7B1: closure by contamination
C7B2: closure by fuel freeze

C8VB1: negative: P2 and P4 telemetry data are normal and they receive gas from the same regulator

C8VB2: negative: pre-launch water flow test confirmed the health of the pressurising system. Cleanliness test afterward was also normal. Thus, contamination is unlikely

C8VB3: negative: we cannot deny hte possibility of fuel vapour penetrating into the pressurising piping system via fuel tank diagphram. However, temp telemetry data suggest that there was no such condition leading to fuel vapour freeze

C8VB4: possible: given specs, testings and tested items we cannot rule out the possibility of valve mulfunction- see CV-F FTA

C8VB5: negative: each value of P1, P2, and P3 which relates to fuel pressurising gas system is stable after VOI-1

C8VB6: negative: given the remaining fuel amount this is not possible. The diagphram cannot move to a position where it closes the tank outlet

C8VB7: negative: impossible because P3 is supposed to rise to the value of P2 immediately after VOI-1, but it took about one hour before this happened

C8VB8: negative: telemetry data after VOI-1 start for acceralation and tank are in unison

C8VB9: negative: Ditto

C8VB10: negative: increase in fuel supply will lead to an increase in propulsion. However, given observed acceralation no excessive propulsion was generated

Please note that the yellow arrow pointing to the connection between C4B1 and C5B1 indicates the position at which fuel tank pressure P3 decline is reflected into this particular FTA

(Please note: connection line from C2B1, going past C3B2, is leading to a number "1". There is no explanation on this page about this, P)

Box connection is as follows.

1. D3>C2B1>C3B1>C4B1>C5B1>>> C8VB1

2. D3>C2B1>C3B1>C4B1>C5B2>C6B1>C7B1>>> C8VB2

3. D3>C2B1>C3B1>C4B1>C5B2>C6B1>C7B2 >>> C8VB3

4. D3>C2B1>C3B1>C4B1>C5B2>C6B2 >>> C8VB4

5. D3>C2B1>C3B1>C4B1>C5B3 >>> C8VB5

6. D3>C2B1>C3B1>C4B2>C5B4 >>> C8VB6

7. D3>C2B1>C3B1>C4B2>C5B5 >>> C8VB7

8. D3>C2B1>C3B1>C4B2>C5B6 >>> C8VB8

9. D3>C2B1>C3B1>C4B3 >>> C8VB9

10. D3>C1B1>C3B2 >>> C8VB10

P

This FTA has a continuation through "1"

P

Page 7: 1.3 Throat rear burn FTA (continuation)

This continues from afformentioned "1"

C1B1: insufficient oxidant supply
C1B2: excessive oxidant supply
C1B3: injector apperture anomally

C2B1: insufficient oxidant pressurising gas pressure
C2B2: excessive pressure damage to oxidant liquid system
C2B3: oxidant tank leak from oxidant liquid system
C2B4: closure by salt formation
C2B5: closure by contamination
C2B6: deformation by errosion

C3B1: bad regulation
C3B2: excessive pressure damage to gas system
C3B4: between tank and port P4
C3B5: downstream of P4

C4VB1: negative: P4 telemetry data is normal

C4VB2: negative: Ditto

C4VB3: negative: each pressure (P1, P2, P4) after VOI-a relating to oxidant pressurising gas system is normal

C4VB4: negative: since P4 telemetry data is normal there cannot be an excessive pressure damage between tank and P4

C4VB5: negative: acceralation and tank pressure telemetry data since VOI-1 start are in unison

C4VB6: negative: increased oxidant supply will lead to an increase in propulsion. However, observed acceralation tels us that no more excessive prpulsion than aniticipated did not take place

C4VB7: negative: injector temp telemetry data is within the range tested on the ground and injector temp did not reach the temp range leading to an errosion

Box connection is as follows (through "1", of course)

1. C1B1>C2B1>C3B1 >>> C4VB1

2. C1B1>C2B1>C3B2 >>> C4VB2

3. C1B1>C2B1>C3B3 >>> C4VB3

4. C1B1>C2B2>C3B4 >>> C4VB4

5. C1B1>C2B2>C3B5 >>> C4VB5

6. C1B1>C2B3 >>>>>>> C4VB6

7. C1B2 >>> C4VB7

8. C1B3>C2B4>>> C4VB8

9. C1B3>C2B5 >>> C4VB9

10. C1B3>C2B6 >>> C4VB10

P

Page 8: 1.4 Unstable burn FTA

C1B1: box D4

C2B1: unstable burn at 152 s

C3B1: insufficient fuel supply
C3B2: excessive fuel supply

C4B1: insufficient fuel pusher gas pressure
C4B2: excessive pressure damage to fuel liquid system
C4B3: fuel leakage to outside from fuel liquid system

C5B1: bad regulation
C5B2: excessive pressure damage to gas system
C5B3: gas leakage from gas system
C5B4: closure of fuel tank outlet
C5B5: excessive pressure damage to the link between tank and port P3
C5B6: excessive pressure damage to the link between port P3 and injector

C6B1: piping closure
C6B2: closure of Cv-F (shaded)

C7B1: closure by contamination
C7B2: closure by fuel freeze

C8VB1: negative: P2 and P4 telemetry data are normal and they both receive gas supply from the same regulator

C8VB2: negative: pre-launch water flow test confirmed the capacity of the pressurising system. Post cleanliness test was normal and there cannot be contamination leading to piping closure

C8VB3: negative: we cannot deny the possibility of fuel vapour penetratinginto the pressurising piping system through the tank diagphram, but temp measurement results say that there was not such a low temp state which may lead to fuel vapour freeze

C8VB4: possible: we cannot rule out the possibility of mulfunction, given specs, testings, and tested items. See CV-F FTA for more details

C8VB5: negative: each pressure (P1, P2, and P3) after VOI-1 relating to fuel pressurising gas system is stable

C8VB6: negative: given remaining fuel amount there is no way that the diagphram might have moved to a position where it could have blocked the fuel tank outlet

C8VB7: negative: after VOI-1, P2 is supposed to go up to the level of P3 immediately, but in reality it took about one hour before this happened, so out of question

C8VB8: negative: telemetry data for acceralation and tank pressure since the start of VOI-1 are in unison

C8VB9: negative: Ditto

C8VB10: negative: increased fuel supply should lead to an increase in propulsive power. However, observed acceralation (Thank you!, NASA, P) no more excessive propulsion than planned occurred

Box connection:

1. D4>C2B1>C3B1>C4B1>C5B1 >>>>>>>>>>>> C8VB1

2. D4>C2B1>C3B1>C4B1>C5B2>C6B2>C7B1 >>>> C8VB2

3. D4>C2B1>C3B1>C4B1>C5B2>C6B2>C7B2 >>>> C8VB3

4. D4>C2B1>C3B1>C4B1>C5B2>C6B2 >>>>>>>>> C8VB4

5. D4>C2B1>C3B1>C4B1>C5B3 >>>>>>>>>>>>>> C8VB5

6. D4>C2B1>C3B1>C4B2>C5B4 >>>>>>>>>>>>>> C8VB6

7. D4>C2B1>C3B1>C4B2>C5B5 >>>>>>>>>>>>>> C8VB7

8. D4>C2B1>C3B1>C4B2>C5B6 >>>>>>>>>>>>>> C8VB8

9. D4>C2B1>C3B1>C4B3 >>>>>>>>>>>>>>>>>> C8VB9

10. D4>C2B1 >>>>>>>>>>>>>>>>>>>>>>>>>> C8VB10

Notes:

1. The number "2" comes from between C2B1 and C3B1, past C3B2 box, leading to another part of FTA (acutally continuing into the second part of this unstable byrn FTA, P)

2. The yellow arrow up top, pointing at the link between C4B1 and C5B1 says that this is the position at which fuel tank pressure, P3 decline is refelected with this FTA

Pandaneko

Page 9: 1.4 Unstable burn FTA (continuation)

This FTA continues from the numer "2" up top left corner

C1B1: insufficient oxidant supply
C1B2: excessive oxidant supply
C1B3: injector aperture anomally

C2B1: insufficient oxidant pusher gas pressure
C2B2: excessive pressure danage to oxidant liquid system
C2B3: oxidant leakage from oxidant liquid system
C2B4: closure by salt formation
C2B5: closure by contamination
C2B6: deformation by errosion

C3B1: bad regulation
C3B2: excessive pressure damagae to gas system
C3B3: gas leakage
C3B4: between tank and P4
C3B5: downstream of P4

C4VB1: negative: P4 telemetry data is normal

C4VB2: begative: Ditto

C4VB3: negative: each pressure (P1, P2, and P4) relating to oxidant pressurising gas system after VOI-1 is stable

C4VB4: negative: since P4 telemetry data is normal there is no part between tank and P4 which suffered an excessive pressure damage

C4VB5: negative: telemetry data of acceralation and tank pressure after VOI-1 are in unison

C4VB6: negative: Ditto

C4VB7: negative: increased oxidant supply should lead to an increase in propulsion, but (thanks to NASA, P) observed acceralation tells us that no more excessive propulsion than anticipated occurred

C4VB8: negative: even if salt was formed at the end of the test manouvour our ground test confirms that the salt will have sublimated during the time after the test manouvour up to VOI-1 (more than 5 months)

C4VB9: negative: confirmed by cleanliness test. Also, there is a filter upstream. Thus, this possibility is low.

C4VB10: negative: injector temp telemetry data is within the range tested on the ground and the temp did not reach the region which may lead to errosion

(Note: There is an independent shaded box at lower left with a character string. Please ignore these since there is no shaded box on the FTA here, P)

Box connection as follows

1. C1B1>C2B1>C3B1 >>>>>>>>>>>>>>>>>>>> C4VB1

2. C1B1>C2B1>C3B2 >>>>>>>>>>>>>>>>>>>> C4VB2

3. C1B1>C2B1>C3B3 >>>>>>>>>>>>>>>>>>>> C4VB3

4. C1B1>C2B2>C3B4 >>>>>>>>>>>>>>>>>>>> C4VB4

5. C1B1>C2B2>C3B5 >>>>>>>>>>>>>>>>>>>> C4VB5

6. C1B1>C2B3 >>>>>>>>>>>>>>>>>>>>>>>>> C4VB6

7. C1B2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>> C4VB7

8. C1B3>C2B4 >>>>>>>>>>>>>>>>>>>>>>>>> C4VB8

9. C1B3>C4B5 >>>>>>>>>>>>>>>>>>>>>>>>> C4VB9

10. C1B3>C4B6 >>>>>>>>>>>>>>>>>>>>>>>> C4VB10

Pandaneko

Page 10: 1.5 Injector thrust direction anomally FTA

(Please note that from this FTA on I will slightly change the formt of my translation scheme. For example, with this particular FTA, the first mimi-mimi column would have been C1B1, but it is simply a box D5 and not worth desiginating a column number to it. So, it will be simply called as such, box D5.

Similarly, I have up until now, suffixed the verdict box numbers with its column number. I will no longer employ this and simply call them verdict boxes from top down, as these boxes always appear extreme to the right, P)

D5:

C1B1: injector thrust anomally

(between this box and C2B1, there is a line leading out to number "3"

C2B1: insufficient fuel supply
C2B2: excessive fuel supply

C3B1: insufficient fuel pusher gas pressure
C3B2: excessive pressure damage to fuel liquid system
C3B3: fuel leal to outside from fuel liquid system

(please note that the yellow arrow here refelects the position at which fuel tank pressure P3 decline is refelected with this FTA, P)

C4B1: bad regulation
C4B2: excessive pressure damage to gas system
C4B3: gas leak from gas system
C4B4: closure of fuel tank outlet
C4B5: excessive pressure damage to the line between tank and port P3
C4B6: excessive pressure damage to the line between port P3 and injector

C5B1: closure of piping (seems too vague, I think, P)
C5B2: closure of CV-F (this box is shaded, i.e., suspect)

C6B1: closure by contamination
C6B2: closure by fuel freeze

VB1: negative: P2 and P4 telemetry data are normal, and they receive gas supply from the same regulator

VB2: negative: pre-launch water flow test confirmed the capacity of the pressurising system. Post testing cleaning was normal. Thus, closure by contamination is extremely unlikely

VB3: we cannot rule the possibility of fuel vapour penetrating into the pressurising piping system via fuel tank diagphram, but temp measurement data suggest that there was no such a low temp status which may lead to fuel (vapour) freeze

VB4: possible: given specs, testings, and tested items we cannot rule out the possibility of mulfunction. See CV-F closure FTA for more details

VB5: negative: each pressure value (P1, P2, P3) relating to fuel pressurising gas system after VOI-1 is stable

VB6: negative: gieven the remaining amount of fuel, diagphram movement to a position where it may block the fuel tank outlet is impossible

VB7: negative: P3 value, immediately after VOI-1 , is supposed to rise to the same level as P2, but in reality it took about one hour before this happened. Thus, this possibility can be ruled out

(Is this not in itself abnormal?, if it took longer?, P)

VB8: negative: acceralation and tank pressure telemetry data since VOI-1 start are in unison

VB9: negative: Ditto

VB10: negative: increased fuel supply should lead to an increase in propulsive power, but observed acceralation tells us that no more excessive propulsion than anticipated occurred

Box connection

1. D5>C1B1>C2B1>C3B1>C4B1 >>>>>>>>>>>>>>>> VB1

2. D5>C1B1>C2B1>C3B1>C4B2>C5B1>C6B1 >>>>>>> VB2

3. D5>C1B1>C2B1>C3B1>C4B2>C5B1>C6B2 >>>>>>> VB3

4. D5>C1B1>C2B1>C3B1>C4B2>C5B2 >>>>>>>>>>>> VB4

5. D5>C1B1>C2B1>C3B1>C4B3 >>>>>>>>>>>>>>>> VB5

6. D5>C1B1>C2B1>C3B2>C4B4 >>>>>>>>>>>>>>>>>>>> VB6

7. D5>C1B1>C2B1>C3B2>C4B5 >>>>>>>>>>>>>>>>>> VB7

8. D5>C1B1>C2B1>C3B2>C4B6 >>>>>>>>>>>>>>>>> VB8

9. D5>C1B1>C2B1>C3B2 >>>>>>>>>>>>>>>>>>>>>> VB9

10. D5>C1B1>C2B2 >>>>>>>>>>>>>>>>>>>>>>>>>> VB10

Pandaneko

During the rest of this evening here, I will be able to upload "Page 11: 1.5 Injector thrust direction anomally FTA (continuation)". And, that will be the end of FTA section of the Investigation 2.2 dated 27 December 2010.

However, there is another FTA further on and there is a very large table ahead. Anyway, I will not be able to go into the FTA summary during the course of this evening.

P

Page 11: 1.5 Injector thrust direction anomally FTA (continuation)

This is coming in through number "3" up top.

C1B1: insufficient oxidant supply
C1B2: excessive oxidant supply
C1B3: injector thrust aperture anomally

C2B1: insufficient oxidant pusher gas pressure
C2B2: excessive pressure damage to oxidant liquid system
C2B3: oxidant leakage from oxidant liquid system
C2B4: closure by salt formation
C2B5: closure by contamination
C2B6: deformation by errosion

C3B1: bad regulation
C3B2: excessive pressure damage to gas system
C3B3: gas leakage
C3B4: between port P3 and tank
C3B5: downstream of port P4

VB1: negative: P4 telemetry data is normal

VB2: negative: after VOI-1, each pressure value (P1, P2, P4) relating to oxidant pressurising gas system is stable

VB3: negative: Ditto

VB4: negative: since P4 telemetry data is normal there is no portion between the tank and pport P4 which was damaged by excessive pressure

VB5: negative: acceralation and tank telemetry data pressure since the start of VOI-1 are in unison

VB6: negative: Ditto

VB7: negative: increased oxidant supply should lead to an increase in propulsion, but observed acceralation indicates that no more excessive propulsion than anticipated took place

VB8: negative: even if salt was formed after test manouvour the salt should have sublimated during the time before VOI-1 (more than 5 months) and this has been confirmed by ground tests

VB9: negative: cleanliness test confirms this. Also, there is a filter upstream. We can rule this out

VB10: negative: injector temp telemetry data is within the range tested on the ground and it did not reach the temp range which might cause errosion

Box connection (coming in from number "3" (circled, P), up top left

1. C1B1>C2B1>C3B1 >>>>>>>>>>>>>>>>>>>>>> VB1

2. C1B1>C2B1>C3B2 >>>>>>>>>>>>>>>>>>>>>> VB2

3. C1B1>C2B1>C3B3 >>>>>>>>>>>>>>>>>>>>>> VB3

4. C1B1>C2B2>C3B4 >>>>>>>>>>>>>>>>>>>>>> VB4

5. C1B1>C2B2>C3B5 >>>>>>>>>>>>>>>>>>>>>> VB5

6. C1B1>C2B3 >>>>>>>>>>>>>>>>>>>>>>>>>> VB6

7. C1B2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> VB7

8. C1B3>C2B4 >>>>>>>>>>>>>>>>>>>>>>>>>> VB8

9. C1B3>C2B5 >>>>>>>>>>>>>>>>>>>>>>>>>>> VB9

10. C1B3>C2B6 >>>>>>>>>>>>>>>>>>>>>>>>>> VB10

Pandaneko

Page 12: 1.6 FTA summary


FTA results given at the first Investigation meeting filtered out 5 items as suspects. As a result, we have filtered out CV-F closure as the cause for all these suspected items.

In what follows we will describe CV-F outline and its history in orbit and examine further, through FTA, what led to the closure of CV-F.

Note: Here, "Closure" , means both complete closure and also partial closure by which flow rate is reduced.

P

Page 13: 2. Trying to find out what went wrong with CV-F

2.1 Outline of CV-F

With space craft like Akatsuki which employ 2 liquid propulsion system it is a normal prectice to install an in-reversible valve at the gas system side.

This is because 2 liquid propulsion system uses self-igniting mixture of fuel and oxidant. If fuel and oxidant vapours are mixed inside the high pressure gas supply system, in the worst case, it will lead to an explosion.

Therefore, it is vital to prevent this vapour mixture from happening at the wrong place and one of the means to prevent this is CV-F valves.


Opening mechanism:

CV is a valve, passive valve, and functions as depicted in the schematics below. (Actually, between main text groups, P)
Incidentally, the valve is normally closed.

When the differential pressure between up and down streams goes above a certain prescribed value (Cracking pressure: 0.117 Mega Pascal D (whatever this D means, P) the valve moves to the left and flow channell is opened.

Closing mechanism:

When differential pressure decreseas while the valve remains open and reaches a certain prescribed value (re-seat pressure: 0.014 Mega Pascal D (whatever this D means, P), then the valve is pushed back by the coil spring and the flow channell is closed.

Explanation of the schemtatics: (Please refer to the original Japanese page for the schematics, P)

The left schematic is the closed valve. My translation goes clockwise from extreme left box.

downstream (that is the extreme left box, P)
coil springs
valve
seal
upstream
He gas in
main body of CV-F
opened state

Against this on the right is another schematic, which depicts closing of the valve

down stream (extreme left box, P)
coil springs
valve
seal
up stream
main body of CV-F
closed state

(seems to me, a very harmless and simple mechanism, cannot possibly go wrong, can it? So, the rest of JAXA investigation is looking more and more like a good mystery story to me. We will find the answer to the mistery as their story develops... I just cannot believe this valve went wrong! P)

P

Page 14: 2.2 History of propulsion system in orbit (large table)

(Here immediately below, C1B1 to C6B1 are headers, P) (Also, I am treating each table section as a box and even sub-divisions belonging to the same leftmost column are treated as separate entities. As a result, same box numbers appear twice as we move along the table, P)

C1B1: Dates
C2B1: events
C3B1: fuel tank operation
C4B1: valve status
C5B1: fuel tank pressure P3, mega Pascal
C6B1: oxidant tank pressure P4, mega Pascal

C1B2 21 May
C2B2: pre-launch
C3B2: (none here, P)
C4B2: close except HLV-1
C5B2: 0.265
C6B2: 0.292

C1B2 21 May 2010
C2B3: post-launch probe separation/initial orbit manouvour
C3B3: regulation
C4B3: HLV-2,3 : close>open>close
LV-F 1,2 : close>open>close
C5B3: 1.458
C6B3: 0.265

C1B3: (a llong, single box)

4 times of blow down operation for wheel unloading (RCS burn for reducing reaction wheel momentum, using a few cc of fuel each time)

C1B4: 24 June 2010
C2B5: pressurising oxidant tank: HLV-1,2 and GLV-1,2 were opened over the period of 24 and 25 June and waited for pressure settlement

C3B5: regulation
C4B5: HLV-1,2 close >open
GLV-1,2 close >open

C5B5: 1.472>1.472
C6B5: 0.251>1.362

C1B5: 25 June 2010
C2B5: same as C2B5
C3B5: regulation
C4B6: HLV-1,2 open>close
GLV-1,2 open>close
C5B5: 1.472>1.472
C6B6: 0.251>1.362

C1B6: 28 June 2010
C2B6: test manouvour
C3B6: regulation
C4B7: HLV-2,3 close>open>close
GLV-1,2 close>open>close
OLV-O/F close>open>close

Note: normally closed LV was opened and test manouvour performed, then closed again after the manouvour

C5B6: 1.472>1.373
C6B6: 1.348>1.389

C1B7: 8 September and 21 September 2010

25 times of wheel unloading by blow down operation. It is believed that pressure change induced differential pressure, due to fuel consumption on wheel unloading, led to the mulfunction of CV-F

C1B8: 21 October 2010
C2B8: suplementing fuel tank pressure
C3B8: (none here, P)
C4B9: HLV-2,3 close>open>close
C4B8: 1.362>1.431
C5B8: 1.431>1.431

C1B9: 5 times of wheel unloading by blow down operation

C1B10: 8 November 2010
C2B10: TRM-1, delta V
C3B10: regulation
C4B11: HLV-2,3 close>open>close
C5B10: 1.431>1.389
C6B10: 1.444>1.417

C1B11: (a long single box, P) 3 times wheel unloading by blow down operation

C1B12: 22 November 2010
C2B12: TRM-2, delta V
C3B12: regulation
C4B12: HLV-2,3 close>open>close
C4B12: 1.403>1.444
C5B12: 1.431>1.431

C1B13: (a long single box, P) wheel unloading once by blow down operation

C1B14: 1 December 2010
C2B14: TRM-3, delta V
C3B14: regulation
C4B14: HLV-2,3 close>open>close
C5B14: 1.472>1.472
C3B14: 1.431>1.431

C1B15: (a long single box, P) 2 times wheel unloading by blow down operation

C1B16: 6 December 2010
C2B16: preparing for VOI-1
C3B16: regulation
C4B17: HLV-2,3 close>open
GLV-1,2 close>open
OLV-O/F close>open

Note: LV open status was confirmed a day earlier to VOI-1, and only OME system valve was closed again

C4B16: 1.472>1.472
C5B16: 1.431>1.431

C1B17: 7 and 8 December 2010
C2B17: VOI-1
C3B17: regulation
C4B17: HLV-2,3 open>close>open

Note: these were closed automatically after VOI-1, but opened again automatically at the time of safe hold mode, and then closed again

CLV-1,2 open>close

Note: these were closed automatically after VOI-1

OLV-O/F close>open>close

Note: these were opened before VOI-1, and automatically closed after the burn

C5B17: 1.472>1.334
C6B17: 1.417>1.417

This is the end of the large table translation. Up it goes!

P

Page 15: 2.3 Orbital environment of CV-F

1. 21 May: CV-F behaviour during the tankpressurising operation immediately after the launch was just as expected and the valve functioned normally

2. 28 June (test manouvour): CV-F valve did not engage itself as the fuel amount used was so small. Thus, we cannot make any judgement here

3. 21 September and 22 November: differential pressure between down stream and upstream of CV-F was small. No judgement possible here

4. 8 September and 21 October: no high frequency telemetry data available here and no judgement

5. 7 December (VOI-1): we will show analysis result in section 2.4, but it is believed that the valve at this stage was closed

In the following graph we will show the history of pressure and temp imposed on the CV-F before VOI-1 termination. We also indicated the positions with a circle at which liquid is thought to have flowed to the CV-F valve.

(about the graph itself, P)

the first character string op top left is: test manouvour

left axis is : temp in centigrade
right axis is: pressure in mega Pascal
horizontal axis down below is: dates, year/month/date in this order

(about the small box inside the graph, P)

1. solid green line: fuel tank temp
2. dotted black line: gas system valve module (around P2) temp
3. solid black line: regulated pressure (P2)
4. thick solid red line: fuel tank pressure (P3)
5. thin solid red line: oxidant tank pressure (P4)

P

Page 16: 2.4 Estimating the degree of CV-F closure

In order to fascilitate cause finding of CV-F closure during VOI-1 we conducted an estimate of the degree CV-F closure.

In particular, we used P3 pressure recovery during both in orbit and the ground test environment in order to estimate the CV-F equivalent orifice area.

Materials used for estimation:

1. estimated value of empty volume of fuel tank immediately after VOI-1

2. Differential pressure between regulated pressure (P2) and fuel tank pressure (P3) as measured on board

We used these to evaluate the gas flow amount into the fuel tank:

1. Value converted from the time of AT alone: 0.54 mmX2
2. Value at the time of pressure recovery after VOI-1: approx. 0.05 mmX2


P

Page 16: 2.4 graph itself

Left axis: estimated equivalent orifice area in mmX2
Right axis: differential pressure (P2-P3) in mega Pascal

1. character string in the graph pointing with dotted red arrow: normal function
2. character string p@ointing with solid thin blue line: pressure recovery after VOI-1

There is a box on this graph and its contents are, from top to bottom:

1. white triangle: AT test 1
2. cirle: AT test 2
3. diamond: full scale water flow test
4. black triangle: 21 May
5. black square: VOI-1, 7 December 2010

P

Page 17: 2.5 Estimating the causes for CV-F closure, FTA

We conducted more detailed FTA. The numbers (Exxx) on the extreme right column relate to those on the investigation plan as we discuss it in section 4.1

C1B1: closure of CV-F (tree top)

C2B1: bad seal area
C2B2: increase in sliding resistance

C3B1: bad materials matching due to use of different materials
C3B2: temp induced change in sealing material characteristics
C3B3: material deterioration due to time ellapse
C3B4: excessive valve insertion due to viscous deformation
C3B5: excessive valve insertion due to long term reverse pressure imprint
C3B6: excessive valve insertion due to excessive reverse pressure
C3B7: bad materials matching due to use of different materials
C3B8: bad clearance between valve and valve supporting system
C3B9: bad alignment of valve and valve supporting system
C3B10: bad surface of valve and valve supporting system
C3B11: external contamination migrating into gap
C3B12: friction sliding formed pieces migrating into gap
C3B13: adhesion due to material formed by fuel and oxidant

C4B1: clearance deterioration due to temperature
C4B2: clearance deterioration due to bad fixing of valve to valve module
C4B3: bad design and bad manufacturing
C4B4: wear and roughing of surface due to friction sliding motion
C4B5: surface corrosiono due to incompatible materials
C4B6: bad manufacturing
C4B7: alien material formation in fuel environment
C4B8: unexpected number of valve function (movement)

VB-E1: possible: test records currently under scrutiny

VB2: negative: temp envoronment was within the spec range throughout operation right from the time of valve delivery

VB3: negative: deterioration possibility is extremely low because the material used was of rank A listed on MSFC-HDBK-527

VB4-E2: possible: cannot be ruled out right now

VB5-E3: possible: cannot be ruled out right now

VB6: negative: it has been confirmed that the maximum reverse pressure while in orbit was 0.045 MPaD from the telemetry data. This possibility is extremely low. Also, we checked, on delivery, the normal function after MEOP (2.08 MPa)

VB7-E4: possible: cannot be ruled out right now

VB8: negative: extremely unlikely because temp remained within the spec range up to VOI-1

VB9-E5: possible: cannot be ruled out right now

VB10-E6: possible: cannot be ruled out right now

VB11-E7: possible: cannot be ruled out right now

VB12-E8: possible: cannot be ruled out right now

VB13-E9: possible: cannot be ruled out right now

VB14-E10: possible: cannot be ruled out right now

VB15-E11: possible: cannot be ruled out right now

VB16-E12: possible: cannot be ruled out right now

VB17-E13: possible: cannot be ruled out right now

(Please note that I have added E- numbers, when applicable, immediately after the verdict numbers for simplicity, P)
(I will upload the box connection separately later as my wife is about shout with a dinner call, P)

Page 17: 2.5 Estimating the causes for CV-F closure (continuation)

Box connection:

1. C1B1>C2B1>C3B1 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>>VB1 (shaded)

2. C1B1>C2B1>C3B2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>VB2

3. C1B1>C2B1>C3B3 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>VB3

4. C1B1>C2B1>C3B4 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>>VB4 (shaded)

5. C1B1>C2B1>C3B5 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>>VB5 (shaded)

6. C1B1>C2B1>C3B6 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>VB6

7. C1B1>C2B2>C3B7 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>>VB7 (shaded)

8. C1B1>C2B2>C3B8>C4B1 >>>>>>>>>>>>>>>>>>>>>>>>>>>>VB8

9. C1B1>C2B2>C3B8>C4B2 (shaded) >>>>>>>>>>>>>>>>>>>>>>VB9 (shaded)

10. C1B1>C2B2>C3B8>C4B3 (shaded) >>>>>>>>>>>>>>>>>>>>>VB10 (shaded)

11. C1B1>C2B2>C3B9 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>VB11 (shaded)

12. C1B1>C2B2>C3B10>C4B4 (shaded) >>>>>>>>>>>>>>>>>>>>VB12 (shaded)

13. C1B1>C2B2>C3B10>C4B5 (shaded) >>>>>>>>>>>>>>>>>>>>VB13 (shaded)

14. C1B1>C2B2>C3B10>C4B6 (shaded) >>>>>>>>>>>>>>>>>>>>VB14 (shaded)

15. C1B1>C2B2>C3B11 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>VB15

16. C1B1>C2B2>C3B12 (shaded)>C4B7 (shaded) >>>>>>>>>>>>>>VB16 (shaded)

17. C1B1>C2B2>C3B12 (shaded)>C4B8 (shaded) >>>>>>>>>>>>>>VB17 (shaded)

18. C1B1>C2B2>C3B13 (shaded) >>>>>>>>>>>>>>>>>>>>>>>>>VB18 (shaded)

P

Page 18: 2.5 Estimating the causes for CV-F closure FTA (continuation)

(This comes in through the circled number "4" up top left, P)

C1B1: parts break, parts drop out, parts squeezing
C1B2: insufficient valve opening power
C1B3: flow channells other than seal area were closed

C2B1: subjected to unexpected environments
C2B2: (shaded) valve functioned a lot more times than expected
C2B3: (shaded) coil springs drop out
C2B4: insufficient differential pressure
C2B5: change in springness
C2B6: closure by contamination from outside the craft
C2B7: closure by alient material formation

C3B1: mechanical environment
C3B2: environment at launch and storage period

VB1: negative: mechanical environment at launch was normal and CV-F functioned normally during the initial operation after launch (21 May)

VB2: negative: after delivery of the valve up to VOI-1 mechanical environments were normal (temp, humidity, ambient gas) and stayed within specified ranges

VB3: (shaded) possible: we cannot deny the possibility of chaterring etc under real conditions in orbit, leading to unexpected behavoiur

VB4: (shaded) possible: cannot be ruled out

VB5: negative: from the telemetry data we know that the maximum value of differential pressure at the time of failure was approx. 0.5 MPa (P2: 1.43 MPa and P3: 0.95 MPa) and this value is well above the cracking pressure (spec value: 0.11 MPa)

VB6: negative: after delivery up until VOI-1 the temp for CV-F stayed within the specified range and springness change is impossible

VB7: negative: given normal result of cleanliness test, accumulation of contamination that will block the flow channell (3mm in diam.) is impossible

VB8: negative: alien material formation leading to blockage of flow channell (diam. 3 mm) is impossible

Box connection

1. C1B1>C2B1>C3B1 >>>>>>>>>>VB1

2. C1B1>C2B1>C3B2 >>>>>>>>>>VB2

3. C1B1>C2B2 (shaded) >>>>>>>>>>>>>>VB3

4. C1B1>C2B3 (shaded) >>>>>>>>>>>>>>VB4

5. C1B2>C2B4 >>>>>>>>>>>>>>>>>>>>VB5

6. C1B2>C2B5 >>>>>>>>>>>>>>>VB6

7. C1B3>C2B6 >>>>>>>>>>>>>>>VB7

8. C1B3>C2B7 >>>>>>>>>>>>>>>VB8

(This is the end of this particular FTA, P)

P

Page 19: 2.6 Summary of the estimation of possible causes for CV-F failure

Here below, we summarise cause candidates filtered out as a result of CV-F FTA.

E-1: Materials mismatch due to use of different materials for the seal areas
E-2: excessive valve insertion due to stickiness (?, P) deformation of the seal areas
E-3: excessive valve insertion due to long reverse pressure imprint
E-4: materials mismatch due to use of different materials at the friction sliding parts
E-5: clearance worsening due to bad fixing method
E-6: bad design and manufacturing of the friction sliding part
E-7: bad alignment of valve suport sturucture and the valve
E-8: errosion and surface roughing due to friction sliding
E-9: surface errosion due to inappropriate materials used for friction sliding parts
E-10: bad manufacturing of the friction sliding parts
E-11: fuel environment forming substance and it getting into the system
E-12: friction sliding producing substance and it getting into the system, due to the unexpected number of valve operation
E-13: substance formed by fuel and oxidant and it causing stickyness at the friction sliding parts
E-14: unexpected number of valve operation leading to mechanical damage, drop out of parts, and glitch (I am not sure about this word, P, it means something getting into gaps and gasp will stay fixed)
E-15: coil springs drop out

(please note that above translations are to the best of my knowledge and I have had to imagine a lot from the original texts.

In particular, I do not know the word off-hand that means something getting into gaps and stay there to prevent the system from moving. Here, I used the word "glitch", but I am not sure if it is the right word, P)


In order to check up on each of these suspected items we will conduct what follows.

1. re-checking of design and manufacturing information
2. testings of individual components
3. testings and experiments using real valves

Concrete information on each of these will be given in section 4.1

P

Page 20: 3. Scenario leading from CV-F closure up to OME burn stop

In the earlier report "Investigation 1-2" we showed that it is possible to close in on CV-F closure as the main culplit for the causes of attitude anomally and subsequent burn stop.

Given this, we conducted a series of FTAs in "Investigation 2-2" in order to further filter out likely candidates.

In this section we will try and reproduce what might have caused CV-F closure and at the same time sort out various phenomina into a coherent scenario.

P

Page 21: 3.1 Considering the fuel tank pressure profile

From the acceralation telemetry data during OME burn we carried out plotting of burn pressure, changes in fuel consumption, tank vacant volume and fuel tank pressure, P3.

If we overwirte it with P3 history, the history is roughly consistent with the telemetry data.

With this estimation, we used the probe parameters before the start of OME burn (predicted mass, predicted tank vacant volume, and fuel tank telemetry data), and if we assume that CV-F was almost closed (section 2.4) we can then quantitatively explain the decrease in the fuel tank pressure.

(There is a graph with this page. Vertical axis on the left is the fuel tank pressure, P3, in MPa. Horizontal axis in seconds is the relative ellapse of time from the time of OME burn start.

Data points with a circle is the telemetry data. Data points with a cross is the estimated value, P)

P

Page 22: 3.2 Estimating the amount of fuel supply during VOI-1 burn

Here, we estimated the propulsive power using the fuel tank pressure, oxidant tank pressure, and acceralation as measued on board and based on these values we estimated the brun pressure.

We also estimated the fuel supply, oxidant supply from the pressure difference between supply pressure and burn pressure.

With the decline in fuel tank pressure fuel supply to OME was accordingly reduced. However, on the other hand, oxdiant supply was carried out normally. Thus, it is estimated that O/F nominal value (0.80) was cinreased up to 1.13 at the time of 152 seconds.

Reduced fuel tank pressure means changes in fuel supply to OME, and O/F ratio. We estimated, based on the data obtained on board, fuel supply to OME during VOI-1.

(There is a graph with this page. Vertical axis on left is the estimated flow rate in Kg/s, and the horizontal axis is the relative time ellapse from the time of OME burn start.

Data dots with a solid blue disc is fuel flow, red solid triangle is oxidant flow, P)

P

Page 23: 3.3 Consideration of acceralation profile

Here, we estimated the acceralation during OME burn from fuel tank pressure, P3 and oxidant tank pressure, P4 during OME burn , using the values of OME propulsion data expected from the ground tests and analysis and OME fuel consumption.

Estimated acceralation result was almost consistent with the telemetry data and we can explain, quantitatively, decrease in acceralation as a result of fuel tank pressure decline.

Note: the initial value used was that of expected probe mass before OME burn

(about the graph here, the vertical axis on the left is acceralation in mX2/s, horizontal axis is relative ellapse of time in seconds from the time of OME burn start, P)

Data points:

1. white circle : acceralation estimated from P3 and P4
2. solid line: telemetry data of acceralation

P

Page 24: 3.4 OME function history during VOI-1

Here, in the graph, superimposed on the test parameters obtained from ground tests during development stage, is the estimated history during VOI-1.

From this, we can see that the burn was being conducted well outside the expected operational range.

(about the graph itself, P)

Vertical axis on left: oxidant tank pressure in MPa
Horizontal axis: fuel tank pressure in MPa

character string left of the graph says: at 152s after VOI-1 burn start
character string right of the graph says: VOI-1 burn start

(are these not the other way round?,P)

the small box on graph lower right contains data points types, they are from top to bottom:

1. white circle: AT real (whatever this means, P)
2. white triangle: QT real
3. solid dark square: VOI-1 X+152 s

thin red line from outside the graph points at a small rectangle area in the middle of the graph and the character string explanation for this, sitting just outside the graph area to the right says: designed operational range.

Note: For clarification we superimposed on the graph straight lines corresponding to constant O/F ratio and also curved lines corresponding to constant propulsive power obtained from ground tests.

P

Page 25: 3.5 Unexpected burns beyond the designed operational range (imaginary schematics page)

(There are 5 engine schematics on this page, D1, D2 to the left and D3,D4, and D5 to the right. With each of these there is a box sitting on the engine with some explanation. As I look at the schematics, I cannot easily follow their explanation, I am afraid, P)

D1: thruster nozzle break due to excessive thermal flow

Excessive thermal flow led to excessive thermal stress near the throat and nearby region (nozzle and throat) was broken, leading to irregular generation of torque

Box on D1: region which may lead to break, upstream of nozzle and throat

D2: thruster nozzle break due to film thruster direction anomally

changes in film cooling thrust direction led to insufficient thruster cooling, leading further to thruster nozzle break and irregular torque generation

Box on D2: imaginary state in which film cooling becomes insufficient due to film cooling thruster direction anomally

D3: throat rear burn

due to throat rear burn, burn gas peeling off and leading to irregular torque generation

Box on D3: burn reaction downstream of throat

D4: unstable burn

burn becomes unstable leading to irregular torque generation

Box on D4: unstable burn

D5: injector thrust direction anomally

there is anomally in the flow of burn gas from the injector, leading to abnormal mixing and burn with irregular torque generation

Box on D5: fuel abnormal burn and bad mixing

P

Just to let you know, am still reading your posts with grateful interest..... This analysis is going
into impressive depth.

Page 26: Estimating probe's external torque generation during VOI-1

Here, we try to estimate the torque affecting the probe due to the factors described in section 3.5

With the telemetry data we have angular velocity recorded 8 times per second, and cumulative RCS firing duration recorded twice per second. Using these values we estimated external torque generated and affecting the probe, based on the values of torque based on the probe's angular velocity and subtracting from them RCS attitude control torques by RCS burn.

However, with estimation of attitude control torque, we do not have history of every 2 seconds RCS firing and as a result we are not able to know its exact history.

For this reason, we looked at two possible cases. One is where atittude control torque remained constant, the value of which is estimated from the cumulative firing duration recorderd every 2 seconds. The other is where the torque generation was not stable during the 2 second period inerval.

This is the reason for the range of estimated values as there is a freedom of choice in the assumption of these shifts within the 2 second period.

(about the graph on this page, P)

Vetical axis on left: external torque in Nm
Horizontal axis: relative time ellapse since OME burn start in seconds

(there are 4 character strings on the graph and these are, from top down, P)

1. range of improbability of external torque (around X-axis): indicated with black dotted lines

2. external torque around X-axis

3. external torque around Y-axis

4. range of improbability of external troque (around Y-axis): indicated with blue dotted lines

(I am not exactly sure about my translation of "external", litterally speaking it says OUTSIDE DISTURBING, but since no meteorite collided with the probe, everything is internal, no?, P)

P

Page 27: 3.7 About the probe's attitude anomally judgement parameters and how they changed

Atittude anomally was caused by the external torque generated as we estimated in the earlier page.

The graph that follows from here is the plotting of the telemetry data (0.5 Hz) of attitude anomally judgement parameter (pease refer to NOTE below) calculated from the attitude angle discrepancy/error and angular velocity discrepancy/error.

The design was such that if the said parameter exceeded for longer than 5 seconds continuously those designed/prescribed values ( 5 Nm around X and Y axises, and 2.5 Nm around Z-axis) the probe is supposed to judge that it can no longer hold the current attitude and this logic actually worked and the probe shifted into attitude maintain mode.

NOTE: With the Investigation 1-2 on page 10, we used the word "control torque". However, in order not to confuse this with the actual atittude control torque as calculated from other factors (calculus etc) we decided to use "attitude anomally judgement parameter" insetad.


(about the graph on this page, P)

vetical axis: atittude anomally parameter in Nm
horizontal axis: relative time shift since OME burn start in seconds

(There are 4 boxes on the graph and one character string, P)

1. top box in the middle: shifting into atittude maintain mode (157.625 s to 158.625 s) and indicated by the pale blue zone on the graph

2. character string roughly in the middle of the graph: continuation for 5 seconds

3. left bottom corner's horizontally long top box: attitude anomally judgement threshhold (5 Nm)

4. line explaining box at the lower left bottom:

4.1 blue diamond: around X-axis
4.2 red square: around Y-axis
4.3 green triangle: around Z-axis

End of this page, P

Page 28: Estimated scenario from CV-F closure to burn stop

From earlier considerations we have the following scenario for the process from CV-F closure up to OME burn stop. This scenario can explain, without contradictions, all of the irregular telemetry data relating to the process.

(about the graph, or chart itself, P)

Time line is to the left of page, starting from OME burn start at 0 sec, down to 152 sec, and then on to 158 sec, all to the left of the long vertical dark and thin bar.

(to the right of this time line, there are boxes, and further to the right there are 4 character strings, and I will translate these one by one, P)

boxes are, from top to bottom,

box 1: closure of CV-F
box 2: fuel supplypressure decline/fuel flow to burn area decline
box 3: mizture ratio in the burn chamber going out of the designed range
box 4: phenomina taking place due to above box 3/ thruster nozzle break, or burn anomally
box 5: external torque generated affecting the probe attitude
box 6: probe's attitude anomally
box 7: attitude anomally judgement parameters observed for longer than 5 seconds continously
box 8: autonomous control actitivated and the burn stops

character strings on the right, from top group to bottom group are as folows,

1. measurements indicating trouble (reported at the first Inverstigation meeting)

2. fuel tank pressure, P3, decline and slow decline in probe's decceraltion

3. rapid change in probe's decceralation and attitude control anomally

4. propulsive system's response to stop motions/ shift to attitude maintain mode/ shift to safe hold mode/ propuslsive system pressure returning to normal

(end of this page, P)

P

Page 29: 4. Investigation plan for clarifying the causes

It is estimated that Akatsuki's failure is due to OME burn anomally. Closure of CV-F led to the decline in fuel tank pressure, pressure dropping below planned value and the mixture ration of F/O went out of designed range.

In order to investigate above mulfunctions we propose following tests, such as analysis/reproducing of CV-F actions, analysis/ reproduction of OME burn status at the time of abnormal condition, analysis/ reproducing of burn chamber and nozzle

P

Page 30: 4.1 Investigating the causes for CV-F mulfunctioon (table, P)

(with this table, top row is the header, but I will treat every section on this table as before, by giving them column and row numbers, P)

C1B1: classification

C2B2: checking available infromation and analysis
C2B3: parts testings
C2B4: real valve used in testings

C3B1: relevant event number
C3B2: E-1, 4, 6, 7, 10
C3B3: E-8, 9, 11
C3B4: E-13
C3B5: E-5, 12, 14, 15
C3B6: E-2, 3
C3B7: E-11, 13

C4B1: test title
C4B2: checking of design/manufacturing information and analyse
C4B3: ambient (?, P, not vapour, but this does not say vapour) fuel friction test
C4B4: salt forming status checking test
C4B5: action tests
C4B6: long duration reverse pressure imprint tests
C4B7: ambient (?, as before, P) fuel action tests

C5B1: test pieces used
C5B2: none
C5B3: equivalent test piece
C5B4: none
C5B5: CV-F (flight spare item and equivalent piece)
C5B6: CV-F (ditto)
C5B7: CV-F (ditto)

C6B1: investigation contents
C6B2: Check CV-F design/manufacturing info from manufacturer and analyse

1. check force balance, seal, mechanical design, resonance frequency of each part, friction sliding clearance, etc

2. analyse external (?, P) loading effects

3. continue dialogue with manufacturer re test results and analysis

C6B3: Analyse fuel vapour affecting friction and friction sliding characteristics

1. carry out pin-on disc tests (NOTE) under fuel ambient (?, P), and after that observe friction sliding surface, sampling of formed matters/analysis

2. carry out approx. one month long test first, and as required, continue with approx. 6 months long tests (reproducing real probe environment)

NOTE: this test presses a pin against a rotating disc surface and simulate the friction sliding

C6B4: Evaluate the effects of salt formation and the effects of fuel/oxidant vapour dispersing upstream beyond CV-F and the latch valve

1. analyse and evaluate the amopunt of dispersion/migration of fuel vapour into upstream of CV-F and the latch valve

2. confirm salt forming situation by letting the saturated fuel vapour react in a transparent column. Here, we will be using normal amount of flow and abnormal amount of flow when both (fuel and oxidant) systems CV are normal and abnormal

3. after checking salt formation status, we will further examine the possibility of tests using real valve (either do it or not, P)

C6B5: Check action status of CV-F in real conditions

1. check action status with CV-F alone and with sub-systems also, as erequired, in order to see what happens both downstream and upstream of CV-F with in-orbit conditions such as flow rates

2. monitor by non-destructive method, such as accerometer, whether unexpected chattering etc happened (or not) in orbit

C6B6: Check seal area deterioration while long term reverse pressure imprint on imposed on CV-F


1. real probe environment simulation by subjecting CV-F to long term reverse pressure and then checking the ability of CV-F (such as cracking and re-seat pressures) and carry out evaluation

2. initial test of approx. one month and depending on the result, continue with the test for further 6 months or so, (real probe environment simulation)

C6B7: Check effects on CV-F by ambient fuel (?, P)

1. with this test we will decide to carry it out or not by the result of the ambient fuel friction test and that of salt formation test

2. we will supply fuel vapour to CV-F from downstream and oxidant vapour to CV-F from upstream, and if possible, we will try and observe salt formation in situ

3. we will initially start with approx. one month long test and if neccessary continue with approx. 6 months long test in order to simulate the real in-orbit conditions for the craft

(end of this particular page, P)

Off you go! P

Page 31: 4.2 Evaluating the effects suffered by OME (table, and same translation scheme as before,P)

C1B1: classification

C1B2: water flow test with injector
C1B3: ground burn test
C1B4: burn analysis
C1B5: destruction analysis

C2B1: corresponding event number

C2B2: D2 and D5
C2B3: no entry
C2B4: D1, D3, D4 , (D2), (D5)
C2B5: D1
C2B6: D1, D2, D3, D4, D5
C2B7: D1

(actually, I may not need to translate these above, but earlier I was worried about similar entries and had to translate them just in case. Just in case problem is this. It is to do with the coding system used. It is not easy just by the look of the alphabets if they are normally coded, or coded with our coding sytem here which is double the normal coding system to cope with Chinese characters used here.

However, Ralph was able to look at the piping scheme page with lots of alphabetical characters on it and found no problem, so I assume that I will not need to translate alphabetical characters from now on. If you have problems, let me know and I will translate them, P)

C3B1: test title

C3B2: injector water flow test
C3B3: thruster function characteristics test
C3B4: reproduction of anomally test
C3B5: after break function evaluation test
C3B6: numerical fluid mechanical analysis of thruster burn
C3B7: evaluation of thruster break probability

C4B1: test pieces to be used

C4B2: idintical injector (newly manufactured)
C4B3: identical injector (newly manufactured) + ceramic thruster (using a spare thruster and also newly manufactured thruster)
C4B4: no entry
C4B5: no entry

C5B1: contents of investigation

C5B2: Carry out injector water flow test under low fuel pressure supply conditions

*: check thrust burn status of the fuel side alone and check to see if film cooling thrust direction may change

**: check status of fuel and oxidant collision and check to see if injector thrust direction may change

C5B3: carry out OME burn test using a wide range of fuel/oxidant supply pressures

*: obtain burn behavoiur and propulsion characteristics outside the designed operational range
**: prepare for following tests and confirm the range in which stable burn can be maintained

C5B4: carry out OME burn under the conditions at the last stage of VOI-1 operation in order to see if VOI anomally actually happens

*: throat rear burn: to be checked by burn pressure and propulsion profile

**: nozzle and throat break: to be checked by a monitor camera (They should have carried one on board in the first place!!!, P)

***: if thruster break is confirmed we will then move on to evaluation of post break propulsion characteristics and the probability of break

C5B5: obtain thruster power characteristics of the destroyed thruster if anomally reproduction test leads to thruster break

*: compare the result with the estimated propulsive power during the 156 to 158 seconds of VOI-1 start

C5B6: refine numerical fluid mechanics codes and apply them to the conditions in which fuel/oxidant supply pressures are more widely ranged

C5B7: carry out thermal stress and mechanical strength analysis using thruster temp distribution if it breaks during the anomally reproduction test, and at the same time check to see where actually the break takes place on the thruster

(Up you go!, P)

P

Page 32: 4.3 Investigation schedule (table, P)

(I am not sure how to deal with this page, but let me try to translate only where character strings reside in the boxes, P)

1. 1st column:

1st box: relating to CV-f
2nd box: relating to OME

2. 2nd column: (must be obvious as these are event numbers in alphabets, P)

3. 3rd column:

1st box contains, from top to bottom, 5 character strings. They are:

1. confirming and analysing available information
2. parts test (components test)
3. reproduction test with real probe time line
4. real valve test, using a real valve
5. reproduction test with real probe time line

2nd box contains 4 character strings and from top to bottom, they read:

1. injector water flow test
2. ground burn test
3. burn analysis
4. destruction analysis

NOTE1: this is the currently foreseen schedule and may change

NOTE2: we have another seperate test in preparation in order to decide if re-insertion attemp is possible, but we do not carry its contents here (what a shame!!!, P, that is exactly what we want to know!!!)

P

It does seem as if JAXA is quite serious about recovering Akatsuki in some sort of operational fashion. This seems to be a very thorough analysis of all possible failure modes, and that is exactly as it should be right now.

Thank you for these updates, Pandaneko!

Page 33: 5. Summary of this second report, Investigation 2-2 (dated 27 December 2010)

We have shown here in this report that we looked at the failure candidates reported at the first investigation meeting (17 December 2010) through FTA and that all of them indeed support the conclusion that CV-F closure led to OME engine stop on detecting attitude anomally.

We have been able to conduct FTA analysis with CV-F closure as the tree top and managed to filter out elements leading to the closure of CV-F. We also have managed to sort these elements out into a few scenarios and showed that these can explain what might have happend

Based on these findings we have set up a test/verification scheme as seen above. From now on, we will carry out these tests and verification programmes along the lines indicated in this report and also, in particular, we will deepen our investigation into the possibility of orbital re-insertion attemp.

(end of this page, and in fact, end of the main report text, and all that remains now are appendices, P)

P

sounds right. External torques are usually (apart from comet encounters, impact torques almost never occur) solar radiation
pressure, aerodynamic torques, magnetic and gravity gradient.

In this instance, as in others (e.g. the misestimation of thruster impulses on Mars Climate orbiter due to the units fiasco), where one
is modeling the performance of the attitude control system, these external torques (which are not usually controlled, and not always
known well) are bundled into a single parameter, called a disturbance torque. Puts all the ignorance in one place.

Much obliged!

Now, what remains to be done is to finish off with the rest of this report, Investigation 2-2, and the only time consuming element is the translation of the original FTA modified, which is rather extensive.

Anyway, having finished off with those I will go back to the parts of Investigation 1-2 (17 December 2010 report) that I left out. As I remember there were 3 major sections still to be translated, including preliminaries (which I hate).

By the time all these have been dealt with I suspect that Paolo may come back with new srouce files. In the meantime, if I can dig out files relating to Nozomi's failure, I might as well translate them. Because, I am interested, just for comparison's sake, if I can find them at all, that is. Can anybody point me in the right direction?

P

fear not I just moved to a more permanent house and for a few weeks I will be living with a slow-speed internet connection...
anyway, thanks a lot for the translation, it is quite an impressive job what you are doing!

We are now coming to the end of Investigation 2-2n dated 27 December 2010

Page 34: A1: Probe outline, this should be selfexplanetary given the glossar pages
Page 35: A2: Piping structure, plase consult glossar pages

Page 36: A3: Modifications made to the FTA as presented at the first investigation meeting (of 17 December 2010)

(here, I just do not want to translate only those parts that have been modified, becasue I find it more time consuming to to check one against the other. It is just too messy and in any event this modified FTA looks different from the original FTA. It is also good to look at the overall picture once agains, is it not?

So, I will translate the whole lot and indicate modified (or additional) boxes, which are shown with characters in white against black background, and I will call these boxes WB inverted, WBI for short, P)

C1B1: burn stop on detecting attitude anomally (tree top)

C2B1: prop system anomally
C2B2: attitude control system (AOCS) anomally
C2B3: external force exerted by a large meteorite

C3B1: irregular torque generation with OME at 152 s
C3B2: attachment anomally at 152 s (nozzle or something else dislocated?, P)
C3B3: fuel gas thrust direction anomally at 152 s
C3B4: RCS anomally at 152 s
C3B5: liquid erruption at 152 s
C3B6: attitude sensor anomally at 152 s
C3B7: attitude control system hardware anomally at 152 s
C3B8: control computer anomally at 152 s

C4B1: fuel gas channell deformation
C4B2: fuel gas peeling ogg or peeling away
C4B3: burn state anomally (unsynmetric burn)

C5B1: thruster nozzle/throat break (see Note 1 and this is a WBI box)
C5B2: burn chamber break (Note 2 and WBI)
C5B3: nozzle inner surface anomally
C5B4: rear throat burn (shaded, that is suspected, P)
C5B5: unstable burn (shaded)
C5B6: injector thrust anomally (shaded)
C5B7: burn chamber inner surface anomally

C6B1: box A, connecting to FTA continuation

VB1: negative: launch environment was all within expectation. We judge from the attitude history that no significant force was exerted so as to cause attachment area's deformation

VB2: negative: (WBI box) we were getting roughly constant acceralation just before VOI-1 stop. We estimate that the propulsion co-efficient is 1.3 as estimated from the acceralation, so our conclusion is that the burn chamber still has the capability of pressure container

VB3: negative: test manoever was completed normally. There is no more factor affecting this situation after the test

VB4: possible: we cannot excluse this possibility as the burn was made under conditions we did not foresee

VB5: possible: Ditto as in VB3
VB6: negative: Ditto as in VB3

VB7: negative: test manoever was completed normally. There is no more factor affecting this situation after the test

VB8: negative: RCS are healthy because normal RCS operations were conducted immediately before VOI and also after VOI start

VB9: negative: attitude sensor is three-fold redundant

VB10: negative: no permanent mulfunction is seen as it is functioning normally now. Telemetry data also suggests that a single event did not lead to a fatal anomally

VB11: negative: designed performance has been confirmed since anomally events

VB12: negative: (WBI box), meteorite collision possibility is extremely low, and also probe is not showing anomally now

NOTE 1: destruction, but still capable of functioning as a pressure container

NOTE2: destruction, and no longer capable of functioning as a pressure container

Factors leading to FTA modifications and reasons for them:

Modification points against reasons for modification as follows

1. thruster nozzle/throat break: we wanted to add a note in order to further clarify the difference between burn chamber and nozzle/throat

2. burn chamber destruction: Ditto and to make these reasons clearer

3. external force due to a large meteorite: modified as earlier comment was not approapriate as the reason

(This completse my tlanslation of Investigation 2-2 report, dated 27 December 2010, P)

From now on, I will go back to Inverstigation 1-2, dated 17 December 2010

P

Apologies, there is a continuation to this FTA, that is for tommrow, or possibly for this evening

P

I found that HORIZONS system has real Akatsuki trajectory after Venus flyby. I have integrated it till January 2017 so we can do some useful analysis for asteroid flyby opportunities.
As of January 1, 2011 spacecraft was quietly cruising along following orbit: q=0.61 AU, Q=0.742 AU, i=3.513 deg, period=203 days.
Numerous flybys opportunities have been detected but just some of these bodies are relatively big. The best five is:
(Dist - closest approach distance in AU, H - absolute magnitude. H=14-17 corresponds to ~2-8 km bodies)

Another opportunity is an observation of comets. There are 2 comets passing nearby the Akatsuki, rather weak comets I should say, but still may be useful for good science:


Attachment to this post contains Akatsuki trajectory in the xyz format + ssc file so you can visualize spacecraft's wandering across the Solar system in your Celestia simulator.

pleasepleasepleasepleasepleasepleasepleaseplease a flyby of Phaethon pleasepleasepleasepleasepleasepleaseplease...
seriously, if JAXA manages to use the OME and change Akatsuki's orbit next April, as they announced, I wonder what is the validity of these predictions

Phaethon would indeed be a terrific target, if it's at all feasible. What sort of probable relative flyby velocities would we be talking about here, several tens of km/sec?

I just checked and Phaethon is in an orbit with an eccentricity of almost .9 (!) and is inclined over 20 degrees. Be thinking the encounter speed is going to be rather high.

It is apparently the parent body for a meteor shower so would that be the first spacecraft encounter with a body like that?

Excellent choice if it can be approached closely and safely. Would be a good choice to add to anyone's list of desirable asteroid encounters, Ceres and Vesta and all the rest we've seen so far close up.

This is really exciting!

Yes, it's the parent body of the Geminids, thought to be either a very volatile-rich asteroid or an extinct comet (tomato, toMAto... )

Definitely an object of scientific interest; it's not your run-of-the-mill NEA for sure. However, given that it's a known emitter of material, even if Akatsuki could achieve a favorable flyby trajectory the question would be whether the spacecraft could survive the encounter long enough to return useful data of any sort.

Why would that be such a worry? A number of spacecraft have survived comet flybys by now, not to mention Cassini which regularly nosedives a known emmiter of material. (potato potAto )

Would Phaethon be 'safer' prior to perihelion rather than after? Assuming the close pass to the sun is what is spalling off the particles?

Although, it occurs to me perhaps applying Poynting /Robertson effects to a computer simulation might suggest a 'safer' trajectory after perihelion passage. If the particles are radially (rel to the sun) pushed JAXA can 'fly' up the opposite side?

Gosh this is fun thinking about. What a great target if they can pull it off!

The thing is, though, that the Geminid stream seems to consist of relatively large particles; the meteors are big & bright. That makes me think that Phaethon may be chucking out 'snowballs' like Hartley does (only bigger & better), and probably also a horde of smaller stuff.

Unlike dedicated comet-chasers, Akatsuki wasn't designed for a high-speed passage through foreign material. I'm concerned that the spacecraft might get sanded before it can play back data from a presumably brief, rapid-relative-velocity encounter.