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Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.iki.rssi.ru/vprokhor/descr/stda.htm
Дата изменения: Wed May 12 18:04:46 1999 Дата индексирования: Tue Oct 2 06:59:08 2012 Кодировка: Поисковые слова: mimas |
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Two types of the orbital data are presented:
The orbital calculations are based on the initial orbital data determined by KIAM RAN using the orbital radio- measurement treatment. The determined initial orbital data are presented as a state vector (satellite position and velocity) in the J2000 reference. The satellite position in the various co-ordinate systems and different parameters along the orbit as a function of time are shown. The orbital information for each month is presented in the separate directory. |
There is a significant difference between satellite motion prediction during flight operation and aposteriory satellite motion calculation.
The orbit disturbance by the attitude control do not permit to use determined initial orbital data (orbital parameters) for long term prediction of the satellite motion.
In fact each set of the orbital parameter corresponding to the epoch T(i) is valid on the time interval, which is covered by measurements, used for this determination. As a rule this time interval is located in the left side of the T(i) and covers the time interval T(i-1) - T(i). The satellite position with preciseness 50-km can be calculated in this time interval. Out of the mentioned time interval the errors grows many times.
The orbital calculation for the long term operations monthly (m) planning is based on the satellite motion prediction for two or more month ahead. The extrapolation approach to the satellite motion calculation is used in this case.
During aposteriory (a) calculation the interpolation approach is used. For the time interval between two orbit's determinations connected with time T(i-1) and T(i) the satellite motion is calculated by using "back" integration from T(i) to T(i-1).
On the STDA server the orbital information for each month is located in the separate directory, which name consists from the year (YYYY) and month (MM) numbers.
The Parent Directory of the Tail Probe orbital data is http://www.iki.rssi.ru/da/interball/tail/orbit/
The Parent Directory of the Auroral Probe orbital data is http://www.iki.rssi.ru/da/interball/auroral/orbit/
For example, the 199808 directory contains the orbital information for August 1998. Each directory includes a set of files, which name and extension indicates its contains and destination.
The name of each file consists from the following components:
|
components |
possible values |
Comments |
|
stage name |
m |
corresponds to orbit predictions for one or more month ahead |
|
a |
corresponds to the aposteriory orbit calculations |
|
|
satellite name |
a |
INTERBALL Auroral Probe |
|
t |
INTERBALL Tail Probe |
|
|
year and month |
YYMM |
two last figures of the year number & month number |
|
decade's number |
d1, d2, or d3 |
this option is used only for the files with extension '.geo' |
For example, the files mt9808.* contain the Tail Probe orbit prediction used during flight operations planning for August 1998.
The files at9808.* contain the results of the aposteriory Tail Probe orbital calculations for August 1998.
The file at9808d1.geo contain the results of the aposteriory Tail Probe calculations for the first decade (1-10) of August 1998 (with couple of day's extension).
In the mostly of files corresponding to the 'm' stage the orbital information is shown as a function of the Moscow time (MT=UT+3h). In some of them the Universal time is used. See below the file's extension list and the reference to its descriptions.
|
# |
extension |
The file contains and reference to its description |
function of the time: |
step |
|
1. |
.ind |
The initial orbital data, used during orbit calculation |
UT |
not determined |
|
2. |
.nod |
The ascending nodes on the Earth's equatorial plane cross-section |
UT |
draconian period |
|
3. |
.se |
The satellite positions in the SE & GSM co-ordinate systems |
UT |
1 h |
|
4. |
.reg |
The predicted simulative regions in the satellite positions |
MT |
1 h |
|
5. |
.bgr |
The simulative regions' borders cross-section |
MT |
not determined |
|
6. |
.vis |
Radio visibility of the satellite for the several groundbased station |
MT |
1 h |
|
7. |
.brv |
The visibility zones for the several groundbased station |
MT |
not determined |
|
8. |
.new |
The predicted angular positions of the Earth and Moon in the satellite centred solar-ecliptic co-ordinate system |
MT |
1 h |
|
9. |
.geo |
Magnetic mapping footprints co-ordinates |
MT |
1 h |
Almost in all files corresponding to the 'a' stage the orbital information is shown as a function of the UT. Accept the file with extension '.bgr', where the Moscow time (MT=UT+3h) is used.
See below the file's extension list and its descriptions.
|
# |
Extension |
The file contains and reference to its description |
function of the time: |
step |
|
1. |
.ind |
The initial orbital data, used during orbit calculation |
UT |
not determined |
|
2. |
.nod |
The ascending nodes on the Earth's equatorial plane cross-sections |
UT |
draconian period |
|
2. |
.se |
The satellite positions in the SE & GSM co-ordinate systems |
UT |
20 min |
|
3. |
.gsm |
The satellite positions in the SE, GSM & SM co-ordinate systems |
UT |
20 min |
|
4. |
.geo |
UT |
10 min |
|
|
5. |
.bgr |
The simulative regions borders cross-section |
MT |
not determined |
|
6. |
.elm |
The osculating elements (as a state vector in the GEI J2000 co-ordinate system) |
UT |
not determined |
|
7. |
.str |
The osculating elements file structure |
UT |
1 day |
|
8. |
.ymd |
The time interval covered by the osculating elements |
UT |
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Dr. Victoria Prokhorenko
Last modified 11 May 1999