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Program STSORBIT PLUS Satellite Orbit Simulation Page 1
Program STSORBIT PLUS
Space Shuttle and Satellite Orbit Simulation
Version 9219
April 30, 1991
by David H. Ransom, Jr.
Rancho Palos Verdes, CA
BBS: (310) 541-7299
BRIEF PROGRAM INSTRUCTIONS
--------------------------
This file is intended to help the experienced user get started with
program STSORBIT PLUS (referred to as STSPLUS hereafter). It is NOT
intended to be a substitute for the full program documentation!
STSPLUS is a program to track the NASA Space Shuttle and other
satellites. Orbital data may be entered manually for space shuttle missions
and NASA/NORAD 2-line elements may be used for all satellites as well as
for the space shuttle when available.
The following steps should get the program "up and running" with as
little fuss and bother as practical.
1. For hard disk users: Copy all files to a subdirectory called STSPLUS.
For floppy disk users: Copy all files to a separate floppy disk.
See the full documentation for discussion regarding the use of RAM
disk to improve program performance for 286+ computers.
2. For hard disk users: Log into the STSPLUS subdirectory using the
following commands (which assume drive C:):
C:
CD \STSPLUS
For floppy disk users: Log into the floppy disk (drive A: assumed):
A:
3. If you have used a previous version of STSPLUS, note that STSPLUS will
not read data from file STSPLUS.INI if it was written by a different
program version. This will eliminate any problems if the format of the
Program STSORBIT PLUS Satellite Orbit Simulation Page 2
.INI file has changed and will reset all features to their default
conditions.
4. Enter the following command to start the program:
STSPLUS (for all CGA/EGA/VGA color systems)
STSPLUS /M (for all EGA/VGA monochrome systems)
5. The program should start and load its map data. The STSPLUS.EXE file
is compressed and is decompressed at load time; this may cause a brief
delay depending upon the computer type used. Once the program is
properly loaded, a screen will appear which requests that you set the
UTC Offset for your time zone. Follow the on-screen instructions and
enter the UTC Offset and the Daylight Flag.
6. The STSPLUS Main Menu will now appear. Press F1 for a demonstration
of the program. Press ENTER to stop the demonstration and return to
the Main Menu.
7. The distribution package includes a set of NASA 2-line elements with a
name like NASA974.TXT. This contains orbital information on over 100
different satellites. Press F2 to load orbital information. The screen
will display a list of files having the extension .TXT. The
NASAnnn.TXT file should be one of them. Enter the file name at the
prompt and press ENTER.
8. The program will ask what satellite you wish to view with a default
response of "HST" (meaning the Hubble Space Telescope). Press ENTER to
accept the default or enter another satellite name (such as "MIR" or
"TDRS"). If the name of the data file begins with the letters "STS",
the default satellite name will be "STS".
9. The program will search the data file for the requested satellite and
display its orbital data if found. If this is the satellite you wish,
press ENTER when asked. Press SPACE to continue searching.
10. After the satellite has been selected, STSPLUS will now display a map
of the world and the ground track of the satellite. The satellite
itself will be a white symbol along the ground track. EGA and VGA
systems will display in color; CGA and HGC systems will display in
monochrome. Press Function Key F1 for on-line help while the ground
track is displayed.
11. Press ENTER at any time to return to the Main Menu.
12. To display a space shuttle mission, press F4 to enter orbital
information in STSPLUS's simple orbital model. Enter the launch time
and date in local time (or use UTC by adding "U" at the end of the
time entry). If you know the orbital altitude and inclination, enter
that information; otherwise, press ENTER to accept the default data.
More accurate NASA 2-line elements are usually available within 24
hours of a space shuttle launch.
13. STSPLUS has many features which are fully described in the program
Program STSORBIT PLUS Satellite Orbit Simulation Page 3
documentation. Please read that documentation!
14. The latest version of STSPLUS and current NASA 2-line elements are
always available on my bulletin board system: RPV ASTRONOMY BBS at
(213) 541-7299, 2400/1200 baud, 8-N-1. The system has a power
controller; if it hasn't answered after the FOURTH RING, hang up and
call back in two minutes. This is a free access BBS with 100MB of
files and is often busy, so please be patient.
USING MISSION ELAPSED TIME WITH 2-LINE ELEMENTS
-----------------------------------------------
The standard NASA/NORAD 2-line orbital element format does not include
the launch time or launch date. However, this information is obviously
required if Mission Elapsed Time (MET) is to be displayed. That information
must therefore be obtained independently and manually entered into the
program. The following steps are required:
1. Start program STSPLUS (see above).
2. Now load the desired 2-line elements using Function Key F2 on the Main
Menu. Press ENTER to return from the ground track display to the Main
Menu.
3. Press Function Key F5 to adjust the orbital information. Since you are
using 2-line elements, the only questions asked will be Launch Time
and Launch Date. Enter the appropriate information. Note that if you
enter UTC or GMT Launch Time (by adding the letter "U" or "G" at the
end of the time, upper or lower case), STSPLUS assumes that the date
you enter will also be the UTC Launch Date.
4. The information will be displayed for approval. Press ENTER to accept
the data, or press SPACE BAR to repeat the process.
5. Once the data have been accepted, press Function Key F6 to display
Mission Elapsed Time. Press F6 again to return to Time Elapsed Since
Epoch. While the ground track is displayed, Function Key F5 may be
pressed to switch between the two elapsed time calculations. (Press
Function Key F1 for help during the ground track display.) If a launch
time and date have not been entered, these commands will have no
effect and time since epoch will always be displayed.
The launch time and launch date will be saved in file STSPLUS.INI and
need only be entered once. Note, however, that this information must be
changed or cleared if you change satellites (since it is saved
independently of the 2-line elements file!). If you display MET for more
than one satellite, it is a good practice to copy file STSPLUS.INI into a
backup file (say, HST.INI for the Hubble Space Telescope) once you have set
the launch time and date. You may then use Function Key F3 from the Main
Menu to reload that file.
The simulated time, taking into account any fast time that may have
been in effect up to that point, is shown at the lower left of the screen.
For reference, the launch or epoch time and the actual local time (as
Program STSORBIT PLUS Satellite Orbit Simulation Page 4
determined by the computer's internal DOS clock) are also displayed. The
MET (Mission Elapsed Time) or T+Epoch display at the lower right of the
screen shows the current elapsed time in the mission and will include an
additional message, "(x10)" or "(x60)", when fast time is in effect.
The combination of the FAST and PAUSE modes will let you "look
ahead" and then freeze the display at a time of interest -- such as when
the satellite enters your circle of visibility. You can then use the "+"
and "-" keys to move the satellite position back and forward in time (using
Function Key F6 to select the time step interval, 1, 10 or 60 seconds) to
determine the times and positions throughout a pass.
One other suggestion: When you use the PAUSE mode (with or without the
"+" and "-" keys), a good practice is to press ENTER twice after you exit
the PAUSE mode to return to the Main Menu and then restart the ground track
display. This resets the position and times to the current time.
USERS WITHOUT A MATH COPROCESSOR CHIP
-------------------------------------
STSPLUS makes very complex calculations to determine the position of
the Earth, Satellite, and Sun. In addition, graphics operations required to
display the maps and the satellite track and position also require many
computer calculations. Slow computers or computers not equipped with a math
coprocessor chip (8087, 80287, 80387, etc.) may not be able to perform all
of the required calculations and still keep the display synchronized to
real time.
In order to allow these computers to run STSPLUS and provide most of
the available features, a special SLOW MODE is available which bypasses or
simplifies some of the more complex or time consuming calculations and cuts
the display update frequency from once per second to once per ten seconds.
From the Main Menu, press Function Key F10 followed by F7. This will
disable the spacecraft circle of visibility feature as well as slowing the
display update cycle to every five seconds instead of every second. Note
that the Sun terminator feature is NOT disabled; however, slower computers
without a math coprocessor chip will be unable to keep up with real time if
this feature is enabled.
PROGRAM REGISTRATION
--------------------
See the file REGISTER for information on registering STSPLUS. While I
do not require registration of STSPLUS, I've put a great deal of time and
effort into the program for more than two years. Registering your copy and
sending along the very modest contribution will encourage me to continue
maintaining and improving the program.
David H. Ransom, Jr.
7130 Avenida Altisima
Rancho Palos Verdes, CA 90274