Category : Science and Education
Archive   : FREQTEXT.ZIP
Filename : MIRTRACK.TXT

HOW TO DECODE THE POSITIONS OF SOVIET
ACADEMY OF SCIENCES SPACEFLIGHT TRACKING SHIPS

The following text file will describe how maritime RTTY monitors
can determine the future positions of Soviet spaceflight tracking ships. In
addition, instructions for decoding "look up" angles as they appear to the
tracking ship are also detailed.

DECODING TRACKING SCHEDULES
The following example involves a tracking ship at the Montevideo-
Buenos Aires "retrofire" position in the South Atlantic Ocean. This
position varies from a spot 1130 nautical miles east of Montevideo,
Uruguay to the area off Tierra Del Fuego.
This "retrofire" position and another off Togo in the Gulf of Guinea,
monitors the telemetry and voice communications from MIR and the landing
phase of all manned flights.
Several times during a deployment of 4-6 months, a tracking ship returns
to a nearby port for fuel and crew changes. Tracking schedules detailing
the orbits and times the ship is able to monitor MIR during its' return to
port are transmitted back to the Soviet Academy of Sciences' marine unit
Science One. This particular tracking ship monitored MIR from a point 1130
miles at sea all the way up the Rio De La Plata during a return to port.
The data is transmitted without descriptive column headings and in a
format similar to encoded aviation weather reports. They can be easily
decoded by using the "QWERTYUIOP" code which substitutes the top line of
letters on a teletype keyboard for the corresponding number keys above them.
For example Q=1, W=2, E=3 ..., with X= "/" and M= ".". Using the
search and replace function of many word processors, the decoding process
can be accomplished in several minutes.
Table 1 is an encoded tracking schedule. Table 2 is the decoded
version. Bracketed letters were added to identify specific columns of data.
With the assistance of Frank Hentschel [75126,72] of Astroforum, who
supplied the MIR's orbital elements, the Soviet data was compared to "look
up" angle tables produced by AMSAT's Orbital Prediction Program - ORBIT
(Copyright 1980 by Dr. Thomas A. Clark).
ORBIT and the tracking ship's data produced an almost identical set of
"look up" angles, confirming that the vessel was monitoring MIR. The data
produced by ORBIT was crucial to identifying what data was being
presented in all 7 columns.
Table 1:
UKBH N!; [A]
[B] [C] [D] [E] [F] [G] [H]
17058 ERTWQ RPTTQ WIOW PERTWE PETRQQ PPQI
17058 ERTPQ RRERQ WOPW QIEEQR QIRWWP PVWP
17058 ERTPQ RRTTQ WOPE WPPIPT WPQUWU PPWR
17058 ERTPQ RTQUQ WOPR WQRTEQ WQTQTQ PPPR
17058 ERROQ RTEOQ WOPT WEWEQR WEWUQO PPPQ
18058 ERROQ RYPQQ WOPY PPTIQQ PQPTWP PPPY
[A] This is the tracking ship's radio call sign: UKBH
UKBH is the Soviet Academy of Sciences spaceflight
tracking ship Kegostrov.
[B] Date: 17058 is 05-17-88
[C] Latitude in degrees/minutes:
34521 = Latitude 34 degrees 52 minutes, South
The last digit indicates the quadrant. 0=North, 1=South
[D] Longitude in degrees/minutes:
40551= Longitude 40 degrees 55 minutes, West
The last digit indicates the quadrant. 0=East, 1=West
[E] Orbit Number:
2892= Orbit 12892 of the orbital complex MIR.
[F] Time of AOS Aquisition of Signal when MIR rises above
the horizon. Time is in Moscow Standard Time (MSK) or
UTC +3 hours. Format is HHMMSS or Hours/Minutes/Seconds.
034523= 03.45.23 MSK or 00.45.23 UTC.
[G] Time of LOS Loss of Signal when MIR descends below
the horizon.
035411= 03.54.11 MSK or 00.54.11 UTC.
[H] Highest elevation above the horizon in degrees
which MIR reaches during this pass.
0018= 18 degrees elevation
Table 2:
[B] [C] [D] [E] [F] [G] [H]
17058 34521 40551 2892 034523 035411 0018
17058 34501 44341 2902 183314 184220 0020
17058 34501 44551 2903 200805 201727 0024
17058 34501 45171 2904 214531 215151 0004
17058 34491 45391 2905 232314 232719 0001
18058 34491 46011 2906 005811 010520 0006

DECODING SOVIET LOOK UP ANGLES
Table 3 shows a side by side comparison of Soviet "look up" angles
with those produced by ORBIT. As before, the data is transmitted in the
"QWERTYUIOP" format. The headers of Soviet "look up" angle tables include
the ship's position and MIR's orbit number. The Soviets use Moscow
Standard Time in their data tables which is UTC plus 3 hours.
Again, ORBIT produced nearly identical "look up" angles for orbit
13015, designated as 3015 in Table 3. The Soviet data is calculated in 30
second steps while ORBIT is accurate to 1 minute steps. NUL54 may identify the
particular retrofire position. At the time, the tracking ship was 107
nautical miles East of Montevideo heading East at 12 knots, or further
out to sea. An hour and a half later and 18 nautical miles further east,
the vessel again tracked MIR along a southwest to northeast track passing
almost directly overhead.

Table 3:
UKBH N!; [Call sign]
NUL54 35121 53501 [Position] [Orbit Prediction for MIR]
2. 3015 [Orbit] [Using ORBIT.EXE]
UTC Time AZ ELEV
22.54.32 209.53 0. 0 1955:16 204 +2
22.55. 0 206.28 1.21 1956:17 194 +5
22.55.30 202. 4 2.54 1957:17 179 +8
22.56. 0 196.53 4.2 1958:18 162 +9
22.56.30 190.49 6.00 1959:19 142 +9
22.56.50 185.58 99 2000:19 124 +7
22.57. 0 183.45 7.27 2001:20 111 +4
22.57.30 175.39 8.41 2002:21 102 +0
22.58. 0 173.7 9.35
22.58.30 156.58 9.5
22.59. 0 147.11 9.58
22.59.30 137.45 9. 8
23. 0. 0 129. 5 8. 1
23. 0.21 123.30 6.59
23. 0.30 221.26 6.37
23. 1. 0 114.48 5. 4
23. 1.30 109. 9 3.28
23. 2.00 104.19 1.53
23. 2.30 100.13 0.20
23. 2.36 99.24 0. 0
The first column of Soviet data is easily recognizable as hours, minutes,
and seconds in Moscow Standard Time. The second column is the Azimuth or
bearing to MIR. The final column is MIR's elevation above the horizon at
the specified bearing.
CONCLUSION
The MIR orbital platform, being permanently manned, requires the
deployment of numerous tracking ships on a continuous basis. Currently,
5 tracking positions have been identified in the North and South
Atlantic: Sable Island (off Nova Scotia, Canada), Gibralter-Canary
Islands, Gulf of Guinea (West Africa), Gulf of Mexico, and Buenos Aires-
Montevideo.