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 19

(3) Space environment at the time of mulfunction being detected

A solar flare of class X occurred on the western area of the Sun's surface on 21 April 2002 with a magnitude of X 1.5 (X-ray flux of 0.15mW/m in the vicinity of the earth). Nozomi received a direct hit of high energy particles associated with this flare on 22 April. As the strength of high energy particles it was the largest since the launch of Nozomi and it is estimated that it was one magnitude higher in energy than anything that Nozomi had experienced earlier. This magnitude is estimated to be such that you normally expect this magnitude in interplanetary space only once or twice during any one solar period (11 years).

For your information the temporal variation of solar proton monitoring by the device on board Nozomi is shown on the graph III-1-6. Also, the high energy particles strength variation experienced by Nozomi since 2000 is shown on the graph III-1-7.


(4) "One bit comms." and grasping of the phenomenon by the autonomous function etc.

It became possible to obtain the data neccessary for the operation of Nozomi (table III-1-2) by establishing a measurement method using Nozomi's autonomous function (note 10). For instance, if you wish to measure the temperature of the inside of the satellite, the beacon is turned either on or off, depending on whether the temp. is above or below the temp. set by the command sent from the ground. (1 bit comms, hereafter) (grapgh III-1-8)

As a result, it became clear that CI-PSU remained in the state of being off. Also, since the possibility of the primary circuit going wrong is extremely low it is estimated that the protection circuit against excessive current flow resisted the CI-PSU from becoming on.

Under these circumstances we expect following phenomena.


① Since TCI is in the off mode a command cannot be issued to TMX. For this reason, it remained impossible to switch between beacon and telemetry modes.


② Since the heat control circuit (HCE) is in the off mode all the heaters inside the satellite controlled by this device are also in the off mode. For this reason, the temp. of the inside of the satellite decreases rapidly to that temp. which is determined by the heat generated by the satellite, sun angle, and the distance to the sun.

Consequently, as shown by the data obtained (table III-1-2) the inner temp. of the satellite decreased below the freezing point of the fuel and attitude control became impossible.

(note 10） : autonomous function

the function which issues a particular set of commands which have been programmed in advance depending on the inside status of the satellite

- 20 -

(and in this instance, we obtained information by making the satellite execute the command which will turn off the power of the power amplifier of the X-band transmitter).

end of page 19

P