Compu-Fix

home *** CD-ROM | disk | FTP | other *** search

/ Compu-Fix / Compu-Fix.iso / misc / sattrack / traksat.doc < prev next >

Wrap

Text File | 1993-03-01 | 297.7 KB | 3,797 lines

╔═════════════════════════════════╗ ║ ║ ║ ▀▀█▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ ║ ║ █ █▀█ █▀█ █ █▀█ █▀█ ▀█▀▀▀ ║ ║ █ █ █ █ █ █ █ █ ║ ║ █ █ █▀█ █▀█ ▀▀█ █▀█ █ ║ ║ █ █ █▄█ █ █ █▄█ █▄█ █ ║ ║ █ ║ ║ █ ║ ║ Version 2.10 ║ ╚═══╦═════════════════════════╦═══╝ ║ ║ ║ Paul E. Traufler ║ ║ 111 Emerald Dr. ║ ║ Harvest, Al 35749 ║ ║ (205) 726-5511 ║ ║ ║ ╚═════════════════════════╝ Satellite Tracking Program 22 May, 1990 ********************************************************************* * * * TRAKSAT is free for NON-COMMERCIAL use only. * * * ********************************************************************* * * * If you find TRAKSAT useful and would like to use it in a * * commercial operation please call or write for more information. * * * ********************* ********************** * * * Paul E. Traufler * * 111 Emerald Dr. * * Harvest, Al. 35749 * * 205-726-5511 (work) * * 205-830-8450 (home) * * * *************************** TRAKSAT makes no warranty of any kind, either express or implied, including but not limited to implied warranties of merchantability and fitness for a particular purpose, with respect to this software and accompanying documentation. Paul E. Traufler, author of TRAKSAT, SHALL NOT BE LIABLE FOR ANY DAMAGES (INCLUDING DAMAGES FOR LOSS OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION) ARISING OUT OF THE USE OF OR INABILITY TO USE TRAKSAT. TRAKSAT Satellite Tracking Program Page 2 TABLE OF CONTENTS ----------------------------------------------------------- INTRODUCTION ........................................... 4 THEORY OF SATELLITE MOTION ............................. 5 HARDWARE REQUIRED TO RUN THE PROGRAM ................... 6 RUNNING THE PROGRAM .................................... 7 ADVANCED FEATURES (MAIN MENU OPTION ZERO) .............. 8 READ SATELLITE DATA (MAIN MENU OPTION ONE) ............. 9 TRACKING STATIONS (MAIN MENU OPTION TWO) ............... 11 REAL-TIME MODE (MAIN MENU OPTION THREE) ................ 13 DELTA-TIME MODE (MAIN MENU OPTION FOUR) ................ 14 GRAPHICS (MAIN MENU OPTION FIVE) ....................... 16 TABULAR OUTPUT (MAIN MENU OPTION SIX) .................. 23 VISIBILITY (MAIN MENU OPTION SEVEN) .................... 27 MULTI-TRACK MODE (MAIN MENU OPTION EIGHT) .............. 28 QUITTING THE PROGRAM (MAIN MENU OPTION NINE) ........... 31 ADVANCED FEATURES OPTION DESCRIPTION ................... 32 REVERSE SOLUTION (ADVANCED FEATURES MENU OPTION 0) ..... 33 USER DEFINED/ALL SATELLITES ............................ 36 ANALYTICAL SOLUTION (LOS/OPTICAL) ...................... 37 NORAD/NASA 2-LINE SATELLITE DATA ....................... 41 WHAT ARE THE MEAN CLASSICAL ELEMENTS ................... 43 MODELS FOR PROPAGATION OF NORAD ELEMENT SETS ........... 48 THE PROPAGATION MODELS ................................. 48 COMPATIBILITY WITH NORAD ELEMENT SETS .................. 49 PROGRAM LIMITATIONS AND ASSUMPTIONS .................... 50 A BRIEF EDITORIAL ...................................... 54 SPECIAL THANKS ......................................... 55 QUESTIONS AND COMMENTS ................................. 56 OBTAINING NORAD SATELLITE DATA SETS .................... 58 FILES REQUIRED FOR TRAKSAT ............................. 59 BIBLIOGRAPHY ........................................... 60 Trademarks used in this document ----------------------------------------------------------------- IBM,PS/2 is a registered trade mark of International Business Machines Corporation. Microsoft MS, MS-DOS, QuickC, are registered trademarks of Microsoft Corporation. Epson FX,LQ, is a registered trademarks of Epson American Inc.. TRAKSAT Satellite Tracking Program Page 3 INTRODUCTION Ever since college I have been interested in satellites and tracking methods. I have often looked up into the night sky and thought, "I know satellites are up there but can I predict when and where to look to see one". I have several small programs to calculate different satellite related quantities but there was not one program available to do all the things I felt a satellite tracking program should do. After several years of working in the aerospace field, I decided that I could take on such a programing task. I started it all with a program called STS, it was geared towards tracking the space shuttle, but used the same basic orbital calculations. STS, version .95, is available on several BBS around the country, see the references at the end of this document. For a first attempt at such a satellite tracking program I was some-what pleased with the results. But I felt there is room for improvement and that is where TRAKSAT steps in. TRAKSAT is a general purpose satellite tracking program, by that I mean any satellite that has a NORAD, NASA 2-Line element set can be used. There are some limitations in the program along with some assumptions, the reader is directed to the section on limits and assumptions for further study. The solution to the satellite motion which is used by TRAKSAT is completely analytic and therefore requires no numerical integration. This makes the program fast, even faster when a coprocessor is used, since the solutions can be evaluated at arbitrarily large, or small, time intervals. The purpose of this program is to provide the user with a means of propagating NORAD element sets in time to obtain tracking information of the space object. TRAKSAT Satellite Tracking Program Page 4 THEORY OF SATELLITE MOTION A complete development of the theory required to predict the position of an artificial satellite about the earth is not presented here because this is not proper place for it. Such a development would require a volume in itself and would be more of a distraction than an aid to the potential user. Only enough of the concepts required for a general understanding plus the final results are given. References to detailed works from which these results are derived are provided for the more than casually interested reader. At the end of the TRAKSAT operating instructions is a brief overview of the fundamentals used in this program and is included to help the reader understand the motion of an artificial satellite about the earth. TRAKSAT Satellite Tracking Program Page 5 HARDWARE REQUIRED TO RUN THE PROGRAM In order to run the program the user will need the following hardware; IBM or compatible PC,XT,AT,PS/2,386, 640K Ram (530K Free Ram required), Floppy or Hard Disk, Text mode display (25x80), Hercules, CGA, EGA, or VGA graphics (used for plotting only), Math coprocessor is NOT required for TRAKSAT, (IF A COPROCESSOR IS PRESENT IT WILL BE USED *), Epson FX-80 printer or compatible (for graphic print out only). * It should be noted that a coprocessor will be 3 to 4 times faster than the emulator version. If the user plans on using the real-time tracking mode, a coprocessor will "smooth out" the time steps to such a small delta as to appear instantaneously. At any rate the real-time mode runs as fast as the host computer can calculate the data and update the screen. ****************** * IMPORTANT NOTE * ****************** If the user will be running TRAKSAT on a 360K floppy drive, it is recommended that the tabular output NOT be directed to a file. The size of the executable and the earth map data plus a satellite data file will not fit on the floppy disk. Therefore NO satellite ground tracks will be available to 360K floppy users. The best solution to the problem would be run TRAKSAT from a hard disk! The prices of hard disks have come down to a point where practically all computers have them. If the user needs a "good reason" to buy a hard disk, perhaps TRAKSAT can convince them to do so. ****************** * IMPORTANT NOTE * ****************** To print out the document, TRAKSAT.DOC use the DOS copy command. The syntax to use would be "COPY TRAKSAT.DOC PRN", without the quotation marks. TRAKSAT Satellite Tracking Program Page 6 RUNNING THE PROGRAM To start TRAKSAT you type "TRAKSAT", without the quotation marks, at the DOS prompt. After a few moments the default tracking station name will be displayed at the bottom of the screen. After the opening screen has been displayed the TRAKSAT main menu will appear. The main menu is the core of the program, i.e. from this menu the user can setup satellite data, tracking station data, and output selections. Here is an main menu example; ╔═══════════════════════════════════════════════════════════════╗ ║ Date: 3/26/1990 Time: 18:30:00 ║ ╠═══════════════════════════════════════════════════════════════╣ ║ ╔═════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠═════════════════════════╣ ║ ║ ║ MAIN MENU ║ ║ ║ ╠═════════════════════════╣ ║ ║ ║ (0) Advanced Features ║ ║ ║ ║ (1) Read Elements ║ ║ ║ ║ (2) Tracking Stations ║ ║ ║ ║ (3) Real Time Tracking ║ ║ ║ ║ (4) Delta Time Mode ║ ║ ║ ║ (5) Graphics ║ ║ ║ ║ (6) Output Data ║ ║ ║ ║ (7) LOS Visibility ║ ║ ║ ║ (8) Multi-Track ║ ║ ║ ║ (9) QUIT ║ ║ ║ ║ Enter Option (0 - 9) ║ ║ ║ ╚═════════════════════════╝ ║ ║ ║ ╚═══════════════════════════════════════════════════════════════╝ the date and time will be the current system values. The date format used is mm/dd/yyyy, while the time format is hh:mm:ss, based on a 24 hour clock, i.e. 14:00:00 is the same as 2 PM. From this menu the input data and output data can be directed. If the user enters other than the listed options numbers an error message will appear at the bottom left of the screen. If the file TRAKSAT.DEF is present the default tracking station from that file will be displayed to remind the user of the default tracking station. To change the default tracking station data see section; Tracking stations, main menu option one. ****************** * IMPORTANT NOTE * ****************** All error messages are displayed for 3 SECONDS, then depending on what the error was, program control will return to the user to correct the problem. It is recommended that the user NOT press any keys while the error message is being displayed, any key presses may cause other error messages to appear. TRAKSAT Satellite Tracking Program Page 7 ADVANCED FEATURES (MAIN MENU OPTION ZERO) The advanced features option will control access to the "Advanced Features" menu. The term advanced features should NOT frighten the potential user off, as the options in this section are NOT hard to use just that some people will never need to use them. For a full description of these menu options see the section; ADVANCED FEATURES MENU. TRAKSAT Satellite Tracking Program Page 8 READ SATELLITE DATA (MAIN MENU OPTION ONE) The main menu option 1 will call the read satellite data menu. This program uses the NASA, or NORAD 2-line satellite element data file format to read data into the program, (in this text the use of NORAD refers to NASA 2-Line or NORAD satellite element data sets). For a full explanation of the NASA 2-line satellite element data sets see section; NASA 2-Line Satellite Data. The read satellite data screen will appear; ╔═════════════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ ║ ║ ║ ║ READ NASA 2-LINE SATELLITE FILE ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ Enter Satellite Filename: [NASA668.TXT ] ║ ║ ║ ║ Enter Search String: [ ] ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═════════════════════════════════════════════════════════════════════╝ the cursor will be placed at the satellite filename position. The program will display the current satellite filename, if this choice is acceptable for the user just press RETURN. If a different satellite data file is desired the user will type in the satellite data filename. The next line requires the name of the satellite to track, a maximum length of 12 characters is allowed. The program will check if the file is present and display an error message if the data file is NOT found. To help the new user a NORAD satellite date file is included with TRAKSAT, see section; Satellite Data Sets. The search method used by the program will locate the first occurrence of what was typed in for a search string when compared to the satellite names, i.e. typing in "mi" could locate the satellite named "Mir". The search is NOT upper/lower case sensitive. If a match is found the full name is displayed and the user is asked to accept this data or read for the next occurrence. If the user does not know ANY satellite names they can enter a carriage return, (Return or Enter), and ALL of the satellite names will be displayed one at a time. TRAKSAT Satellite Tracking Program Page 9 ****************** * IMPORTANT NOTE * ****************** TRAKSAT is limited to the first 2000 satellites in any data file. If the user has more than 2000 satellites in a data file they will need to remove, using a text editor, satellite data sets as to include the desired data set in the 2000 limit. This may not prove to be a limitation for most users as most satellite data set have less than 150 data sets. If no match is found a error message is displayed and the user will try another match. If the file is found and the satellite name has been located the screen will appear like; ╔═════════════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ ║ ║ ║ ║ READ NASA 2-LINE SATELLITE FILE ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ Enter Satellite Filename: [NASA668.TXT ] ║ ║ ║ ║ Enter Search String: [Mir ] ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ Found MIR ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ Satellite Name [MIR ] ║ ║ ║ ║ ║ ║ ║ ║ Keep Reading Satellite File (y/n) [N] ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═════════════════════════════════════════════════════════════════════╝ the next step would be for the user to press return to stop reading the satellite data file and return to the main menu. The routine that reads the NASA 2-line satellite data does a check- sum on the data to insure that the data is correct. If the check- sum fails the user is notified with only a warning message, the data may NOT be correct. The user can still use this data but the results it produces may not be accurate. For a full explanation of NASA 2-line satellite element sets see section; NASA 2-Line Satellite Elements. TRAKSAT Satellite Tracking Program Page 10 TRACKING STATIONS (MAIN MENU OPTION TWO) The next option, number 2, will only need to be run once, unless a different tracking station is used, by the user. The program defaults to using Huntsville, Al. as the tracking station, if the user does not want to use the default option they can select a city from the city data file. The cite data file has over 700 of the larger U.S. cities latitude and longitudes in it. The tracking station search works very much like the satellite name search. The user is asked for a search string and the first occurrence is displayed, then the next one and so on, until no more matches are found. If the user accepts a match some additional data is asked for by the program. The altitude above mean sea level in meters, hours from Greenwich, daylight savings flag (1 = daylight savings, 0 = standard time) , and time zone name, are required for the tracking station. If the altitude of the tracking station are not known the user can enter zero with out to much loss in accuracy. If the user can not find a match to the city data then they will need to use a text editor to add the city data in the file TRAKSAT.CTY. Below is an example for Huntsville, Al.. ╔═══════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ READ TRACKING SITE DATA FILE ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ Enter Search String: [Hun ] ║ ║ ║ ║ ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ Found: Hun ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ Tracking Station Name [HUNTSVILLE, AL ] ║ ║ ║ ║ Keep Reading Tracking Data File (y/n) [n] ║ ║ ║ ║ HUNTSVILLE, AL ║ ║ ║ ║ Enter Altitude Above Sea Level (M) [228.6 ] ║ ║ ║ ║ Enter Hours From UT, i.e. CST = -6 [-5] ║ ║ ║ ║ Enter Daylight Savings, i.e. 1 = Daylight [1] ║ ║ ║ ║ Enter 3 Character Timezone Name, i.e. CST [CDT] ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═══════════════════════════════════════════════════════════════╝ the program pauses for a few seconds to allow the user to review the data for any errors. TRAKSAT Satellite Tracking Program Page 11 ****************** * IMPORTANT NOTE * ****************** If the tracking station changes from the default values the file TRAKSAT.DEF will hold the last saved tracking station data. While running the program if a new tracking station is selected the user will be asked if the old tracking station data should be overwritten or not. If the user saves the current data then the next time TRAKSAT is run that new data will be the default else the old TRAKSAT.DEF will be used. A text editor can be used to change the TRAKSAT.DEF data also, the user will need to use some caution with this method. The TWO EXCEPTIONS are the multi-track options, see the section on its recommended use (MAIN MENU OPTION EIGHT) and the user defined area, see section; Analytical Solution. After the tracking station has been chosen the main menu will appear waiting for the next user choice. TRAKSAT Satellite Tracking Program Page 12 REAL-TIME MODE (MAIN MENU OPTION THREE) If the user would like to track in real-time, press 3, the program defaults to this mode at start-up. The screen will not change if this mode has been selected. The real-time mode will update the screen as fast as the hardware will allow. For an XT class machine with no coprocessor, the update time may be 1 to 2 seconds. An AT class computer with a coprocessor can whip along at about 0.4 seconds per update. The powerful and fast 386 coprocessor equipped machine can sing along at 0.2 seconds per update. The average user will not require this great of detail but it is included for the advanced user. ****************** * IMPORTANT NOTE * ****************** The time is read from the system clock, and as such is only as accurate as the setting of this clock. The software date and time can be set before running TRAKSAT to insure the correct time. Refer to your DOS manuals to use the time and date functions. A brief note about tracking satellites. The accuracy of the data is the most important part of the prediction process. NORAD does track some 8000+ objects in orbit around the earth, and maintains a data base of the objects. The earth modeling and perturbations are the most important factors in satellite tracking. This program uses the NORAD element sets mainly because they are available and have reasonably good accuracy. If the user would like to "see" a satellite in the night sky the precision of 1 or 2 seconds is not important, several minutes may not even be that important. This is not to say that the average person can not locate the satellite, it is going to pass over some site sooner or later, its the time of the passing that is of importance. It could be said that if you tell me where to look for the satellite and tell me about when I should be looking for it the chances are it will be spotted. The sky is a big place and it would be almost impossible to locate a satellite without any help from programs such as TRAKSAT. TRAKSAT Satellite Tracking Program Page 13 DELTA-TIME MODE (MAIN MENU OPTION FOUR) If the user would like to track a satellite from say todays date to some future date, the delta time mode is the choice to use. The basic idea is track from some starting date to some stopping date. At any rate the user will be confronted with the delta time mode screen; ╔══════════════════════════════════════════════════════════╗ ║ ║ ║ ║ ║ ╔═══════════════════════════════════════════════╗ ║ ║ ║ DELTA TIME MODE ║ ║ ║ ╟───────────────────────────────────────────────╢ ║ ║ ║ STARTING DATE AND TIME (UT) ║ ║ ║ ║ ║ ║ ║ ║ YEAR [1990] ║ ║ ║ ║ MONTH [ ] ║ ║ ║ ║ DAY [ ] ║ ║ ║ ║ HOUR [ ] ║ ║ ║ ║ MINUTE [ ] ║ ║ ║ ║ SECOND [ ] ║ ║ ║ ║ TIME STEP (MIN) [ ] ║ ║ ║ ║ ║ ║ ║ ║ Press Esc to QUIT ║ ║ ║ ╚═══════════════════════════════════════════════╝ ║ ║ ║ ║ ║ ╚══════════════════════════════════════════════════════════╝ the user will need to "fill in the blanks". The program will display "defaults" which the user will press return to accept. If the default is not correct the user will be required to enter in a new default. At the start of this section the default date and time are the current local date and zero hours UTC, however, if the user changes the data the next time this section is called the "new" default data will be used. At any time during the delta mode data entry the user presses the Esc key the program will stop the data entry and the Main Menu will appear. It is noted that the maximum length, that is from the starting date to some future time, of the simulation is 99 hours 59 minutes 59 seconds. An example is included for the user to "get the idea" on entering the starting date information. This example starts on 26 december, 1989 at 0 hours UTC, and uses a 1 minute time step. The user can enter smaller or larger time steps depending on the requirements of the user. TRAKSAT Satellite Tracking Program Page 14 ╔══════════════════════════════════════════════════════════╗ ║ ║ ║ ╔═══════════════════════════════════════════════╗ ║ ║ ║ DELTA TIME MODE ║ ║ ║ ╟───────────────────────────────────────────────╢ ║ ║ ║ STARTING DATE AND TIME (UT) ║ ║ ║ ║ ║ ║ ║ ║ YEAR [1989] ║ ║ ║ ║ MONTH [12] ║ ║ ║ ║ DAY [26] ║ ║ ║ ║ HOUR [00] ║ ║ ║ ║ MINUTE [00] ║ ║ ║ ║ SECOND [00] ║ ║ ║ ║ TIME STEP (MIN) [1.0 ] ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════╝ ║ ║ ║ ╚══════════════════════════════════════════════════════════╝ An approach most people use is to pick a 2-3 minute time step and check the output for any passes near the tracking station for that day. Then return back to the delta time mode and use a smaller time step to obtain a better estimate of the satellite visibility. Another method is to use the analytical solution option, see the section on Advanced Features for more information. The next step for the user is the length of time for the propagation. The format is hours,minutes,and seconds. Below is an example for 12 hours, 30 minutes, 0 seconds; ╔══════════════════════════════════════════════════════════╗ ║ ║ ║ ╔═══════════════════════════════════════════════╗ ║ ║ ║ DELTA TIME MODE ║ ║ ║ ╟───────────────────────────────────────────────╢ ║ ║ ║ LENGTH OF PROPAGATION ║ ║ ║ ║ ║ ║ ║ ║ HOUR [12] ║ ║ ║ ║ MINUTE [30] ║ ║ ║ ║ SECOND [00] ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════╝ ║ ║ ║ ╚══════════════════════════════════════════════════════════╝ after the length of propagation is entered the program will return to the main menu. TRAKSAT Satellite Tracking Program Page 15 GRAPHICS (MAIN MENU OPTION FIVE) Option number five, from the main menu, controls the graphics output. If the user selects the graphics output a new menu will be displayed with several options for the user to choose from. A graphics menu screen will appear such as; ╔══════════════════════════════════════════════════╗ ║ ║ ║ ╔═════════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠═════════════════════════════╣ ║ ║ ║ GRAPHICS MENU ║ ║ ║ ╠═════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (1) Ground Tracks ║ ║ ║ ║ (2) Star Background ║ ║ ║ ║ (3) 3D Projections ║ ║ ║ ║ (4) Return To Main Menu ║ ║ ║ ║ Enter Option (1 - 4) ║ ║ ║ ╚═════════════════════════════╝ ║ ║ ║ ╚══════════════════════════════════════════════════╝ The options available from this menu control the graphics output. The user has the choice of satellite ground tracks or star background plots. If the user selects option 1 from the graphics menu a satellite ground track will be produced, while a option 2 will display a star background. The star background option will display visible stars from a database of 58 navigational stars, the Sun, the planets, and the moon. The term "star background" will be used in this document to mean the 58 navigational stars, the Sun, the planets (not including the earth), and the moon. ****************** * IMPORTANT NOTE * ****************** The star data is internal to TRAKSAT, i.e., there are no provisions for the user to modify the star data at this time. Star positions are for Epoch J2000.0, from USNO Floppy Almanac 1988, Version 2.11.88, file STAR1.CAT. The star background is a view looking from the tracking site towards the stars. This plot will be useful for producing a "star map" to take outside with you to compare the night sky with the satellite path. The option to print out this "star map" is included in TRAKSAT, as of version 1.80 and up. The user will require a Epson FX-80 or compatible printer to use this feature. Again this will prove valuable to the user in determining where and when to look to "see" the satellite, this option will work for LOS or Optical visibility modes. To print out a screen copy the user will only have to press a "P" or "p". After the output is printed the TRAKSAT Satellite Tracking Program Page 16 program will continue with the plot. The user can interrupt the printer process by pressing any key, the printer output will stop and the program will continue. ****************** * IMPORTANT NOTE * ****************** The printer MUST be connected to parallel printer port number 1, LPT1. To stop the printer output the user can press any key. A Epson FX-80 or graphics compatible printer must be used for any output. The print out routines have been tested on several different Epson compatible printers without any problems. ****************** * IMPORTANT NOTE * ****************** If the user selects any graphic output the program will test for a graphics adapter and based on the type of graphics hardware will select the "highest" graphics mode supported. An example would be; VGA mode 640x480 pixels, EGA mode 640x350 pixels, CGA mode 640x200 pixels, HGC mode 720x348 pixels (Monochrome). ****************** * SPECIAL NOTE * ****************** The Hercules graphics mode requires running the driver MSHERC.COM, this is the driver supplied with several Microsoft programing languages, before using the TRAKSAT program. Type "MSHERC" and then "TRAKSAT" to start the program. (A TRUE Hercules card works with TRAKSAT, some clone cards may NOT.) I can not test this mode as I do not have any 100% Hercules graphic cards. Dave Ransom (author of ASTRO CLOCK) has tested TRAKSAT on a TRUE Hercules card and had NO MAJOR PROBLEMS. A few problems with the screen cursor but NOT serious. Many thanks to Dave! Do not use a Microsoft mouse AND the Hercules graphics cards together, according to Microsoft, as this may cause some "problems". If the hardware does NOT support graphics an error message will be displayed and the program will return to the main menu. ****************** * IMPORTANT NOTE * ****************** **************************************************************** If the user has a computer that is not 100% compatible or the graphic card is not 100% VGA compatible the program can be forced to use the EGA mode. To use this method invoke the program with "TRAKSAT\EGA", without the quotes. This will set the display to EGA modes only and MAY eliminate any graphic problems encountered. NO OTHER GRAPHIC MODES CAN BE SET THIS WAY. **************************************************************** TRAKSAT Satellite Tracking Program Page 17 (GRAPHICS MENU OPTION 1) If the ground track option is entered (1) the program proceeds to draw a Mercator projection map of the world. The upper left corner is at latitude 90 degrees and longitude -180 degrees, while the lower right corner is latitude -90 degrees and longitude 180 degrees. The grid spacing is 30 degrees from both the latitude and the longitude. A "+" will be plotted for the tracking station coordinates, the coordinates from TRAKSAT.DEF or the currently loaded data. The plotting process may take a minute or two on a slow XT type computer, something under 5 seconds on the particular computer I use. The file EARTH.DAT contains the world map data, some 8200 points in all. This file is compressed to save space and reduce the reading time. If the EARTH.DAT file is not found an error message will be displayed and the program will return to the main menu again. After the world map is displayed the simulation begins. The starting position for the satellite is marked as a yellow circle, this was added to help locate the starting position. The screen will plot the orbital ground trace of the chosen satellite along with other valuable data. The top line will have the UTC date and time, while the second line will have the local date and time displayed. The lower lines will have the tracking data displayed. An example of the output screen would be; -----------------------▌ TRAKSAT Version 1.80 ▐-------------------- | | | UTC 21:37:26.1 Date 12/26/1989 Satellite Name: MIR | | Local 15:37:26.1 Date 12/26/1989 Tracking Station: HUNTSVILLE,AL | | (The version number may be different in this display.) | | (no world map drawn in this example) | | | | Lat 45.1635° Azimuth 309.1281° Range 7115.4 Km | | Long -175.3926° Elevation -30.1331° Rev # 22120 NOT Visible | | | ----------------------------------------------------------------------- The Lat and Long are the satellite latitude and longitude. The Azimuth and Elevation are as seen from the tracking station, while the Range is the distance from the satellite to the tracking station. The azimuth is always between 0 and 360 degrees with north being 0, east 90 south 180 and so on. The elevation will be always be between -90 and +90 degrees. If the elevation is < 0 the satellite is below the horizon as seen from the tracking station. The Rev # is based on the input data starting revolution number plus the number of revs per day times the days past the epoch date, i.e. the formula; rev = rev_epoch + (mean motion(rev/day) * (epoch date - date). TRAKSAT Satellite Tracking Program Page 18 The epoch refers to the NORAD satellite data set, see section; NORAD/NASA 2-Line Satellite Data, for a full explanation of the input data. The last item displayed is based on if the satellite is visible from the tracking station. See main menu option seven for a complete description of the methods used by TRAKSAT to test for visibility. ****************** * IMPORTANT NOTE * ****************** To stop the display the user can press any key and the screen will "freeze". The user will need to press any key again to continue the simulation. If the user presses Esc, escape key, the simulation will stop and the user will be returned to the main menu. ****************** * IMPORTANT NOTE * ****************** The ground track will continue until the user stops the simulation by pressing return twice. After 8-9 ground tracks have been plotted the screen will be "very busy", the user can re-draw the screen by pressing Esc, than pressing main menu option five again. The world map will be drawn again along with the new orbital ground tracks. This will cut down on the screen "clutter". The user can print out the screen output with the ground track option. To print the output of the screen press "P" or "p", without the quotation marks. The print out may take a minute or so depending on the type of printer being used. The print out will start with the upper right side of the screen. (GRAPHICS MENU OPTION 2) If the graphics menu option 2 has been chosen the program will ask the user for some additional data. The user can display the visible star names if so desired. The user will choose what direction to look, i.e., North, East, South, or West. The field of view of the star background is 180 degrees in azimuth and 0 through 90 degrees in elevation. If the user selects North the visible range of the azimuth will be 270 degrees (west) to 90 degrees (east). If the user selects East the visible range of the azimuth will be 0 degrees (north) to 180 degrees (south) with 90 degrees being the center of the screen (due east). The option South will display from 90 degrees (east) to 270 degrees (west). The option for West will display from 180 degrees to 360 degrees with 270 degrees (west) being the center of the screen (due west). An example could be to see a satellite rise out of the west the user would select W, that will display from due south through west to the north. The screen will appear such as; TRAKSAT Satellite Tracking Program Page 19 ╔══════════════════════════════════════════════════╗ ║ ╔═════════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠═════════════════════════════╣ ║ ║ ║ GRAPHICS MENU ║ ║ ║ ╠═════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (1) Ground Tracks ║ ║ ║ ║ (2) Star Background ║ ║ ║ ║ (3) 3D Projections ║ ║ ║ ║ (4) Return To Main Menu ║ ║ ║ ║ Enter Option (1 - 4) ║ ║ ║ ╚═════════════════════════════╝ ║ ║ ╔══════════════════════════════════╗ ║ ║ ║ Display Star Names (y/n)? [Y] ║ ║ ║ ╚══════════════════════════════════╝ ║ ║ ╔══════════════════════════════════╗ ║ ║ ║ Looking N,E,S,W (N,E,S,W) [W] ║ ║ ║ ╚══════════════════════════════════╝ ║ ╚══════════════════════════════════════════════════╝ By default TRAKSAT will display the star names, including the planets and the moon, and look west. The user will only need to change these options by typing in the correct response. An example of a star background would be; UTC 14: 2:12.2 Date 3/26/1990 Az 211.3715° Rev# 23519 Local 8: 2:12.2 Date 3/26/1990 El -43.8641° Vis NOT Visible ---------------------------------------------------------------- | Satellite: Mir TRAKSAT 1.85 | | | 75- | | | | O Moon | 60- | | | | EXAMPLE | 45- (NO PLOT SHOWN) | | (This is only an example, the | | data displayed is NOT correct) | | | | | 30- o Venus | | | | | 15- . Alpharatz | | | | west | ---------------------------------------------------------------- 210 240 270 300 330 the side axis is the elevation while the bottom axis is the azimuth. (Observer coordinates are the only output type at this time). In this example star names were displayed and the option to look west was selected. The "sky track" of the satellite will also be plotted on the screen. The top two lines will display the local and UTC time and dates, azimuth, elevation, rev, and if the satellite is visible (based on the setting of option 7 LOS or TRAKSAT Satellite Tracking Program Page 20 Optical). (The version number may be different in this display.) ****************** * IMPORTANT NOTE * ****************** If the delta time mode is selected time steps are marked on the screen and labeled for the user. It is recommended that the delta time mode be used for star backgrounds so a "time tag" can be placed on the screen. The real time mode will not place "time tags" on the screen. This approach was used to help reduce screen clutter, i.e., to many time tags. This method was chosen because few people have laptop computers "out in the field" to use for viewing aids. A printed "sky map" generated before the nights viewing will be of much greater use to most people. ****************** * IMPORTANT NOTE * ****************** It is noted that the star background will be refreshed EVERY 15 MINUTES, in either delta or real time modes. It is therefore wise to select a starting time about 15 minutes PRIOR to the time of interest and run the program in the delta mode until PAST the time of interest. An example of this would be; Time of interest 11:30:00 UTC, Starting time 11:23:00 UTC, Time span 00:14:00. This will provide the user with the "sky map" from 11:23 to 11:37 UTC and avoid the screen refresh. ****************** * IMPORTANT NOTE * ****************** To stop the display the user can press any key and the screen will "freeze". The user will need to press any key again to continue the simulation. If the user presses ESC, escape key, the simulation will stop and the user will be returned to the main menu. (GRAPHICS MENU OPTION 3) If the user presses option 3 from the graphics menu a 3-D orthographic projection of the earth and the satellite will be drawn. The perspective will be centered on the tracking station coordinates with the altitude above the earth being set by the semi-major axis of the satellite to view. A small "X" will mark the tracking station coordinates. The grid lines are drawn 10 degrees apart with the orthographic projections. The 3-D graphic will plot the "orbital trace" above the planet, i.e., not the ground trace, WHILE HOLDING THE EARTH STILL. The earth will be non-rotating with the satellite going around it. The close earth satellites (1000 Km altitude and less) will produce a good quality plot while near geosync. satellites will display the earth as a small hard to see "ball". The highly TRAKSAT Satellite Tracking Program Page 21 eccentric orbits (ecc > .3) will not display the complete orbital trace due to some limitations of the methods used in TRAKSAT. This should not pose much of a concern to most users. The 3-D projection will be slow on XT type computers without a coprocessor so if the user does NOT want to wait for the complete earth to plot out press any key and the earth land mass plot will stop and the satellite view will start. The screen can be stopped and started the same way as any other graphic modes, i.e., any key to freeze and Esc to stop. At this time the altitude above the earth is not a user changed option. If the user would like a polar (either north or south) projection select Main Menu option 2 and select either the north, south or equator tracking station coordinates. It is recommended that the user edit the TRAKSAT.CTY file and change the first three tracking station coordinates to his or her LOCAL LONGITUDE. The user will answer the questions about tracking station altitude and time zone information based on the local conditions. Below is an example of the TRAKSAT.CTY file with the first three "extra" tracking stations included. The format of the tracking station is; City Name Long. (deg) Lat. (deg). 'North Pole ',-86.5867,90.0 'Equator ',-86.5867,.0 'South Pole ',-86.5867,-90.0 'Rancho Palos Verdes CA ',-118.403334,33.767501 'Calaveras County, CA ',-120.566667,38.15 'Washington (USNO), DC ',-77.06575,38.920556 'Auburn, AL ',-85.4833,32.6067 'Birmingham, AL ',-86.81,33.5169 'Gadsden, AL ',-86.0114,34.0158 'Huntsville, AL ',-86.5867,34.7317 The TRAKSAT.CTY file can hold a maximum of 1000 tracking stations in it. (The file included with TRAKSAT has 722 "cities" in it). TRAKSAT Satellite Tracking Program Page 22 TABULAR OUTPUT (MAIN MENU OPTION SIX) TRAKSAT can also produce a tabular output of the satellite tracking data, the output is in a text mode not graphics. If the user picks main menu option six, the program will display another menu asking if the output is to go to a file or the screen. I chose NOT to include the option for a printer mainly because of all the different printers and the problems that go along with different hardware. However, the file option output can be edited and printed out by the user if so desired. At any rate, the screen will look like; ╔══════════════════════════════════════════════════════╗ ║ ║ ║ ╔═════════════════════════════════════╗ ║ ║ ║ OUTPUT DATA TO SCREEN/FILE ║ ║ ║ ╟─────────────────────────────────────╢ ║ ║ ║ ║ ║ ║ ║ S = Output to Screen ║ ║ ║ ║ F = Output to File ║ ║ ║ ║ ║ ║ ║ ║ Choice (S,F) [S] ║ ║ ║ ║ ║ ║ ║ ║ A = All Passes ║ ║ ║ ║ V = Visible Passes ║ ║ ║ ║ ║ ║ ║ ║ Choice (A,V) [A] ║ ║ ║ ║ ║ ║ ║ ╠═════════════════════════════════════╣ ║ ║ ║ Ra & Dec (J2000 Epoch) ║ ║ ║ ╠═════════════════════════════════════╣ ║ ║ ║ Do you want to display the ║ ║ ║ ║ Ra & Dec coordinates (Y/N)? [Y] ║ ║ ║ ╚═════════════════════════════════════╝ ║ ╚══════════════════════════════════════════════════════╝ the user has to enter S or F. If the user presses any other keys than the S or F the program will default to using the screen for the output. If the user presses the S key the program will display a header with some of the tracking station data and the units of the data. Below is an example of the screen output without the Ra & Dec; Tracking Station: HUNTSVILLE, AL Satellite: Mir DATE TIME (UTC) AZIM ELEV RANGE LAT LONG Rev V HR:MN:SEC DEG DEG KM DEG DEG Thr 25Jan90 01:27:5.550 268.7678 -43.87 9384.23883 -1.65793 -176.815 22575 Thr 25Jan90 01:27:5.600 268.7689 -43.87 9384.00198 -1.65535 -176.813 22575 Thr 25Jan90 01:27:5.660 268.7702 -43.87 9383.72069 -1.65229 -176.811 22575 Thr 25Jan90 01:27:5.710 268.7712 -43.87 9383.48382 -1.64971 -176.809 22575 this example was run using the real-time mode and the default tracking station, Huntsville, Al.. In this case the LONG is the satellites longitude, positive (+) TRAKSAT Satellite Tracking Program Page 23 means EAST longitude while negative (-) means WEST longitude. The column "V" is the visibility flag, i.e., if the satellite is visible the flag is set to "Y" else it is blank. The other output quantities are the same as in main menu option five. If the user had chosen to include the Ra & Dec the output would be like; Tracking Station: HUNTSVILLE, AL Satellite: Mir DATE TIME (UTC) AZIM ELEV RANGE Ra Dec ALT V HR:MN:SEC DEG DEG KM HH:MM:SS DD:MM:SS KM Thr 25Jan90 01:27:15.38 268.9799 -43.57 9337.76175 21:58:19 -01:05:53 388 Thr 25Jan90 01:27:15.44 268.9811 -43.56 9337.47902 21:58:20 -01:05:42 388 Thr 25Jan90 01:27:15.55 268.9835 -43.56 9336.95618 21:58:21 -01:05:22 388 the user will notice that the latitude and longitude have been replaced by the Ra & Dec. ****************** * IMPORTANT NOTE * ****************** The Ra & Dec are based on the J2000 epoch, 1,1.5,2000 UTC date, and are NOT user selectable, perhaps in the next version of TRAKSAT. The J2000 epoch is the "current" epoch on most star charts. The user will notice that the header is stationary just the data is scrolling. This option is useful for a quick view of tracking data, since no graphics are used. If the user was in delta-time mode the step between outputs would be the delta time step value set in main menu option four. ****************** * IMPORTANT NOTE * ****************** To stop the display the user can press any key and the screen will "freeze". The user will need to press any key again to continue the simulation. Pressing ESC will return the user to the main menu. The other option, F, will place the tracking data output into a file. The file name will consist of the first 8 characters of the satellite name with the extension ".PRT" added to the end. The name of the output file will be displayed for the user. An example could be the satellite Mir, the filename for output would be "Mir.PRT". ****************** * IMPORTANT NOTE * ****************** The program will produce the file xxxxxxx.PRT, the x being the current satellite name, if one is not found, but will OVERWRITE TRAKSAT Satellite Tracking Program Page 24 an old one if found. The user will have the responsibility to re- name the file after completing a run if they would like to save the output. The output in the file is very similar to the screen output option. Below is an example of the file output mode; TRAKSAT Version 1.90 Tracking Station: HUNTSVILLE, AL [ Line Of Sight (LOS) Visibility ] Satellite: Mir Satellite Data Set: 1 16609U 86 17 A 90 91.75081924 .00058269 00000-0 66933-3 0 5052 2 16609 51.6174 355.6250 0013230 341.6181 18.4560 15.61365027236165 DATE TIME (UTC) AZIM ELEV RANGE LAT LONG Rev V HR:MN:SEC DEG DEG KM DEG DEG Thr 25Jan90 01:26:42.04 268.26 -44.61 9494.42 -2.86 -177.67 22575 Thr 25Jan90 01:26:42.21 268.26 -44.60 9493.63 -2.86 -177.66 22575 Thr 25Jan90 01:26:42.32 268.27 -44.60 9493.12 -2.85 -177.66 22575 Thr 25Jan90 01:26:42.43 268.27 -44.60 9492.60 -2.84 -177.65 22575 again this example used the real-time mode. This output is a standard 80 columns, for printers or the 25x80 text screen. In this example a line of sight (LOS) mode was chosen. If the visibility mode was optical the header, the line under the tracking station name, would display; [ Optical visibility ]. If the file mode and the real-time mode are chosen the screen will display the number of records that have been written to file. The program DOES check the remaining disk space and stops the program if the record space exceeds available disk space. The data prior to exceeding the disk space is written and an error message is displayed, no data will be lost. It is recommended that the real-time mode NOT be used for file output, mainly because of the large files that could be produced. If the file mode and delta-time mode are chosen the screen will display the same record count as above, but also the total number of records to calculate. This method produces the smallest file size the user requires. The total number of records to calculate would be; total_records = (stop_time - start_time)/delta_time. The size of the file is approximately 82 bytes per record, therefore 1440 records, one day at 1 minute interval, will produce a file size of about 118K. ****************** * IMPORTANT NOTE * ****************** TRAKSAT Satellite Tracking Program Page 25 To stop the display the user can press any key and the screen will "freeze". The user will need to press any key again to continue the simulation. Pressing ESC will return the user to the main menu. The option has been added to TRAKSAT version 1.5, and up, to display only the visible passes, based on the setting of the flag for main menu option 7, or ALL passes. The program will default to ALL if a return is pressed. The output, in the tabular modes, can display Ra & Dec of the satellite also. The coordinate used is based on J2000 epoch, this was chosen to be used with "current" star charts. The default is to include Ra & Dec in the output. TRAKSAT Satellite Tracking Program Page 26 VISIBILITY (MAIN MENU OPTION SEVEN) There are two different methods used by TRAKSAT to determine visibility. The first method is simply when the elevation is greater than 0 degrees the satellite will be visible to the tracking station. This method is called line of sight (LOS) in the program. This method would be suitable for monitoring satellite radio transmissions, interesting RF signals no doubt. It should be noted that at most tracking sites 0 degrees elevation is not visible due to ground based obstructions, i.e. trees buildings, and other such objects. A rule of thumb is if you hold out your arm straight and stick out your thumb horizontal to the ground so it appears to touch the horizon the upper edge of your thumb is about 2 degrees elevation, while your closed fist is about 10 degrees elevation. The second method, optical visibility, requires the satellite to be above zero degrees elevation also, however the satellite must be sun-lit while the tracking station is in darkness. This method would be used for viewing satellites with the aid of say binoculars. It is of interest to note that some satellites are NOT visible even if the elevation angle is above the horizon, because they are in the earth's shadow. It is difficult to observe a satellite "coming out" of the earth's shadow, it is easier to see the entrance into the shadow. If the lighting conditions are favorable a "bright" satellite can be seen with the naked eye also. The best time for these favorable lighting conditions usually occur an hour before sun rise or sun set, as seen at the tracking site. The best type of satellite is low, about 250 - 400 kilometer altitude, ones for naked eye observations. ****************** * IMPORTANT NOTE * ****************** TRAKSAT version 1.60 and above use NAUTICAL twilight, i.e. the sun is -12 degrees BELOW the local horizon, to determine the lighting conditions. The user can not change the type of twilight used in TRAKSAT, i.e., civil, nautical, or astrodynamic. The type of visibility is set from the main menu, the default is to use the LOS method. If the user would like to change the visibility method, select main menu option number seven. The main menu will always print the type of visibility test that will be performed by the program. This menu option is a toggle function, i.e. selecting option 7 changes from one method to the other. ****************** * IMPORTANT NOTE * ****************** With either method the visual magnitude is NOT calculated. Such a calculation would require knowledge about the emissivity of the satellite, and atmospheric conditions, neither of which is readily available to the user. TRAKSAT Satellite Tracking Program Page 27 MULTI-TRACKING (MAIN MENU OPTION EIGHT) TRAKSAT version 1.7 and above have the capability to track several satellites at the same time. The main menu option number eight will bring up another menu, this menu is used for the multi-track option. The multi-track menu will appear asking the user to plot in real time or delta time modes. At this time only ground tracks can be produced with the multi- track option, that is to say no tabular output. Below is an example of the multi-track options menu. ╔═════════════════════════════════════════════════════════════╗ ║ ╔════════════════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ MULTI-TRACK MENU ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (1) Real Time Ground Tracks ║ ║ ║ ║ (2) Delta Time Ground Tracks ║ ║ ║ ║ (3) Return To Main Menu ║ ║ ║ ║ ║ ║ ║ ║ Enter Option (1 - 3) ║ ║ ║ ╟────────────────────────────────────╢ ║ ║ ║ Satellites To Track ║ ║ ║ ║ File: NASA668.TXT ║ ║ ║ ║ Satellite #1 [MIR ] ║ ║ ║ ║ Satellite #2 [SALYUT 7 ] ║ ║ ║ ║ Satellite #3 [IRAS ] ║ ║ ║ ║ Satellite #4 [SEASAT 1 ] ║ ║ ║ ║ Satellite #5 [EGP ] ║ ║ ║ ║ Satellite #6 [NOAA 9 ] ║ ║ ║ ║ ║ ║ ║ ╚════════════════════════════════════╝ ║ ╚═════════════════════════════════════════════════════════════╝ The satellite data file is displayed, this can be changed from the main menu option number one, along with the default satellite names. The user can return to the main menu by pressing option number three. If the satellite data file name is NOT correct then return to the main menu, press 3, and run option number one. Enter the correct file name and any search string, this search string will not be used in the multi-track modes. If the data file is found return to the main menu and run option eight again, this time the correct file will be read. The default file name used for both the single and multi-tracking modes is stored in TRAKSAT.DEF, and can be edited and changed. It is NOT the best way to change the default data but can be used. The program will read the default data at startup and if any changes are made DURING A RUN before the program terminates the user will be asked to save this new data or keep the old data. TRAKSAT Satellite Tracking Program Page 28 ****************** * IMPORTANT NOTE * ****************** The user can ONLY change the satellite names by editing the TRAKSAT.DEF file and changing the default names. The format for the satellite names is as follows; COLUMN 1 - through - 16 CAN BE ANYTHING, COLUMN 16 STARTS THE SATELLITE NAME, THE NEXT 12 CHARACTERS USED ARE THE NAMES OF THE SATELLITES TO TRACK. Below is an example, this is the data included in the TRAKSAT.DEF file. Satellite # 1: MIR Satellite # 2: SALYUT 7 Satellite # 3: IRAS Satellite # 4: SEASAT 1 Satellite # 5: EGP Satellite # 6: NOAA 9 It is recommended that the FULL name of the satellite be used, the search routine will use the first match found and not look for any other matches. If the name of a satellite is not found the output will display a NO DATA, i.e., no data for the requested satellite has been loaded. Six satellites MAXIMUM can be tracked, if the TRAKSAT.DEF has fewer than TWO the program will issue a error and return to the main menu. The ground track options will be plotted if option one or two is chosen from the multi-track menu. The plots are very similar to the main menu option five, except that for every satellite a different colored line is drawn. The order of the colors are; 1st satellite = yellow 2nd satellite = cyan 3rd satellite = green 4th satellite = lite red 5th satellite = lite magenta 6th satellite = lite green. (The colors can NOT be changed by the user) ****************** * IMPORTANT NOTE * ****************** Users with monochrome monitors will have trouble identifying the ground tracks in the multi-track mode as no difference in the colors will be seen. As of TRAKSAT version 1.90 and above a number (1 - 6) along with the "starting circle" is plotted to help identify the satellite on the monochrome screen. Below is an example of the multi-track ground tracks. It is noted that no actual graphics plot is included due to the limits of storing graphics and text together. TRAKSAT Satellite Tracking Program Page 29 -------------------▌ TRAKSAT Version 1.80 ▐------------------ | UTC 17:17:36.3 Date 2/20/1990 Satellite Name: MULTI-TRACKING | | Local 11:17:36.3 Date 2/20/1990 Tracking Station: HUNTSVILLE, AL| | | | (The version number may be different in this display.) | | (no world map drawn in this example) | | | | | | Mir Salyut 7 IRAS SeaSat 1 EGP NOAA 9| |Azi 32.079 227.66 274.10 220.47 4.9673 2.2960| |Ele 14.499 -60.75 -50.48 -57.27 33.954 -15.43| ---------------------------------------------------------------------- The output will display the ground tracks, the azimuth as seen from the tracking station, and the elevation. The elevation is the angle above or below the tracking station horizon. The output is in degrees, with the time and date formats the same as option five. (The version number may be different in this display.) ****************** * IMPORTANT NOTE * ****************** No visibility methods, LOS or optical, are used in the multi- track modes. Perhaps in the next version of TRAKSAT that option will be included. TRAKSAT Satellite Tracking Program Page 30 QUITTING THE PROGRAM (MAIN MENU OPTION NINE) This option will stop the TRAKSAT program and return the user to DOS. If the tracking station data was changed during the program execution, the user will be asked if the new data should replace the old default data. That choice is up to the user to decide. The old data will be displayed along with the current data to help the user with the choice. TRAKSAT Satellite Tracking Program Page 31 ADVANCED FEATURES MENU OPTIONS The advanced features option will control access to the "Advanced Features" menu. If the user selects the zero option the advanced features menu will appear; ╔═══════════════════════════════════════════════════════════════╗ ║ ║ ║ ║ ║ ║ ║ ╔═════════════════════════════════════════╗ ║ ║ ║ ADVANCED FEATURES MENU ║ ║ ║ ╠═════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (0) Reverse Solution ║ ║ ║ ║ (1) All Satellites In Data File ║ ║ ║ ║ (2) Analytical Rise & Set (LOS) ║ ║ ║ ║ (3) Analytical Rise & Set (Optical) ║ ║ ║ ║ (4) Return To Main Menu ║ ║ ║ ║ Enter Option (0 - 4) ║ ║ ║ ║ ║ ║ ║ ╚═════════════════════════════════════════╝ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════════════╝ The user has five options from this menu, the Reverse Solution, All or User Defined Satellites, Analytical Rise & Set (LOS) Solution, Analytical Rise & Set (Optical) Solution, and finally the return to Main Menu options. If the user selects any other options than 0 - 4 the program will return to the Main Menu. TRAKSAT Satellite Tracking Program Page 32 REVERSE SOLUTION (ADVANCED FEATURES MENU OPTION ZERO) The main menu option 0 will perform the "reverse solution", i.e., given a right ascension & declination (Ra & Dec) and time (UTC) determine what satellite was observed. For this method to work the user must take accurate right ascension, declination and UTC time measurements. If the user selects this option a opening warning screen will appear before entering into the reverse solution menu. This warning is to remind the user that accurate measurements (THREE ARE REQUIRED) are needed to obtain acceptable results. The accuracy of the data should be within the abilities of most users with a telescope that has Ra & Dec digital read out or mechanical measurement devises. The observed data set WILL NEED TO BE FROM THE SAME REVOLUTION NUMBER, i.e., A SINGLE PASS NEAR THE TRACKING SITE. TRAKSAT has been tested with several satellites, changing the observed Ra & Dec and times to better determine the accuracy requirements of the reverse solution option. The Ra & Dec can be off about 2 minutes and still produce good results. If the Ra & Dec is off more then 2 minutes the error grows linearly with time. Remember that the closer the satellite element data set is to the observed data the better the match will be. A brief description of the methods used for the reverse solution is located in section; (Program Limitations and Assumptions). The user is given a choice to return to the Main Menu or continue with the reverse solution from this warning message screen. At any rate the reverse solution menu will appear as such; ╔═════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ REVERSE SOLUTION MENU ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ Observation #1 Observation #2 Observation #3 ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ Month [ ] Month [ ] Month [ ] ║ ║ ║ ║ Day [ ] Day [ ] Day [ ] ║ ║ ║ ║ Year [ ] Year [ ] Year [ ] ║ ║ ║ ║ Hour (UTC) [ ] Hour (UTC) [ ] Hour (UTC) [ ] ║ ║ ║ ║ Minute [ ] Minute [ ] Minute [ ] ║ ║ ║ ║ Second [ ] Second [ ] Second [ ] ║ ║ ║ ║ Ra Hour [ ] Ra Hour [ ] Ra Hour [ ] ║ ║ ║ ║ Ra Minute [ ] Ra Minute [ ] Ra Minute [ ] ║ ║ ║ ║ Ra Second [ ] Ra Second [ ] Ra Second [ ] ║ ║ ║ ║ Dec Degree[ ] Dec Degree[ ] Dec Degree[ ] ║ ║ ║ ║ Dec Minute [ ] Dec Minute [ ] Dec Minute [ ] ║ ║ ║ ║ Dec Second [ ] Dec Second [ ] Dec Second [ ] ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═════════════════════════════════════════════════════════════╝ the user will "fill in the blanks". Data entered will be checked for "correct" values, i.e., no 13th month or any other such errors. The "full" year is used, i.e., 1990 NOT 90. TRAKSAT Satellite Tracking Program Page 33 After all of the data has been entered the program will display the search mode screen. The satellite data filename is displayed, the current filename will be used. The screen will appear as; ╔═══════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ READING NASA 2-LINE SATELLITE FILE ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ Looking For Matching Data ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ File: NASA668.TXT ║ ║ ║ ║ Possible Match Data Fit ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═══════════════════════════════════════════════════════════════╝ As the program finds any "matches", i.e., if the satellite could be the observed one, the satellite name is displayed along with a data fit. The data fit is simply the Root Sum Square (RSS) values of the difference between the measured right ascension and declination and the calculated values. The RSS value is then converted into a percent and displayed. A data fit of 100% means the observation data matched a particular satellite, i.e., the observed data fit the predicted satellite position almost perfectly. The data fit is displayed so the user can determine any possible satellites that could have been seen. ****************** * IMPORTANT NOTE * ****************** If the user would like to change the default filename, FIRST run main menu option 1 and select the new satellite filename and ANY satellite data set in that file. This is important because the reverse solution will search the default satellite data file, the default data file being the currently loaded in memory or the filename in the TRAKSAT.DEF file. For more information on changing the default data file see main menu option one. An example is included below to help user with the reverse solution option. (This example is for a UNKNOWN satellite using elements from the NASA668.TXT file.) The tracking station coordinates were for Huntsville, Al.. TRAKSAT Satellite Tracking Program Page 34 ╔═════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ REVERSE SOLUTION MENU ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ Observation #1 Observation #2 Observation #3 ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ Month [3 ] Month [3 ] Month [3 ] ║ ║ ║ ║ Day [27] Day [27] Day [27] ║ ║ ║ ║ Year [1990] Year [1990] Year [1990] ║ ║ ║ ║ Hour (UTC) [3 ] Hour (UTC) [3 ] Hour (UTC) [3 ] ║ ║ ║ ║ Minute [1 ] Minute [3 ] Minute [6 ] ║ ║ ║ ║ Second [0 ] Second [0 ] Second [0 ] ║ ║ ║ ║ Ra Hour [2 ] Ra Hour [8 ] Ra Hour [13] ║ ║ ║ ║ Ra Minute [38] Ra Minute [12] Ra Minute [10] ║ ║ ║ ║ Ra Second [51] Ra Second [22] Ra Second [4 ] ║ ║ ║ ║ Dec Degree[46 ] Dec Degree[56 ] Dec Degree[-21] ║ ║ ║ ║ Dec Minute [47] Dec Minute [29] Dec Minute [17] ║ ║ ║ ║ Dec Second [4 ] Dec Second [44] Dec Second [22] ║ ║ ║ ║ ║ ║ ║ ╚═══════════════════════════════════════════════════════╝ ║ ╚═════════════════════════════════════════════════════════════╝ After all of the observed data was entered the next screen will appear such as; ╔═══════════════════════════════════════════════════════════════╗ ║ ╔═══════════════════════════════════════════════════════╗ ║ ║ ║ READING NASA 2-LINE SATELLITE FILE ║ ║ ║ ╠═══════════════════════════════════════════════════════╣ ║ ║ ║ Looking For Matching Data ║ ║ ║ ╟───────────────────────────────────────────────────────╢ ║ ║ ║ File: NASA668.TXT ║ ║ ║ ║ Possible Match Data Fit ║ ║ ║ ║ Name: Salyut 7 100% ║ ║ ║ ║ ║ ║ ║ ║ End Of Data File ║ ║ ║ ║ Number Of Matches = 1 ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚╡ Press Return ╞═══════════════════════════════════════╝ ║ ╚═══════════════════════════════════════════════════════════════╝ In this example the observed satellite was the Salyut 7, matching the observed data 100 percent. ****************** * IMPORTANT NOTE * ****************** Due to the fact that about 120 of the more than 8000 satellite data sets are included in a typical data file, most of the observed data sets will not find a matching satellite. The only cure would be to have ALL 8000 satellite data sets, this seems HIGHLY unlikely for the average user let alone the advanced user. TRAKSAT Satellite Tracking Program Page 35 ALL/USER DEFINED SATELLITES (ADVANCED FEATURES MENU OPTION ONE) The user has the choice with the analytical solution options to select all of the satellites in the data file or some user defined satellites. The default will be to read ALL of the satellites for these options. The user can define his or her "favorite" satellites, up to 25 satellites can be included. The user will need to use a word processor to edit the TRAKSAT.DEF file and add the satellites names to it. The word processor used will need to save the file in PLAIN ASCII format, i.e., NO SPECIAL CONTROL CHARACTERS EXCEPT THE END OF FILE MARKER. The edlin or PC-Write will do the job nicely for the user. An example of the TRAKSAT.DEF file with user defined satellites is included below; column no. 123456789012 2447836.50000000 HUNTSVILLE, AL 34.7317000 273.4033000 228.60 -5 0 CDT NASA678.TXT Multi-Track Satellite Names Satellite # 1: MIR Satellite # 2: SALYUT 7 Satellite # 3: IRAS Satellite # 4: SEASAT 1 Satellite # 5: EGP Satellite # 6: NOAA 9 User Defined Satellite Names IRAS SALYUT 7 COSMOS 1686 COSMOS 1766 MIR ****************** * IMPORTANT NOTE * ****************** Remember to start the user defined satellite name in column 2. The next 12 characters make up the satellite name, upper or lower case makes no difference. If a user defined satellite is NOT located in the satellite data file a warning message will be displayed. The user defined satellites can be ANY of the satellites included in the data file, however, 25 satellites is the maximum number allowed. If the user has more than 25 satellites then select the All Satellite Data Sets option. The user defined option is a toggle switch, i.e., if the menu shows "All Satellites In Data File" and the user presses option 1 the menu will reappear displaying the "User Defined Satellite" message. The user can toggle back and forth between these two options. TRAKSAT Satellite Tracking Program Page 36 ANALYTICAL RISE & SET (ADVANCED FEATURES OPTION 2/3) TRAKSAT version 2.00 and above has included a very powerful option, Analytical Rise & Set. Many people have asked "why use this analytical approach ?". Three reasons come to mind speed, speed, and speed! The analytical approach used is a closed form solution to the problem of determining when a satellite can be seen (either LOS #2 or Optical #3) by a ground tracking station. In effect, this problem usually involves the calculation of the rise-and-set time (UTC) of a given satellite from a specific ground tracking station. In the past, it has been the custom to solve the problem by letting the satellite run through its ephemeris, and checking at each instant to see whether the elevation angle of the satellite was greater than some minimum value. However, by attacking the problem from a different point of view, that is, with the eccentric anomaly taken to be the independent variable, it is possible to obtain a closed-form solution to the satellite visibility problem. Specifically, the closed-form solution is a single transcendental equation in the eccentric anomalies corresponding to a rise-and-set time for a given orbital pass of a satellite. It is more difficult to solve the controlling equation than the standard Keplerian equation. However, the method offers the advantage that the controlling equation is solved only once per orbit period as contrasted with the hundreds of times the Keplerian equation must be solved with the standard step-by-step technique. "How much faster is the analytical solution ?" Several "benchmarks" were run using the same satellite data sets and starting times to determine the speed of each method. If the user selects the Delta Time Mode and then the Analytical Solution the speed difference will be obvious. ****************** * IMPORTANT NOTE * ****************** The analytical solution methods will use 10 degrees as the minimum elevation angle that the viewer can "see". In practice that "assumption" is very well founded. The minimum is NOT user selectable in this case. An example of the speed comparison is in order to back-up these claims. The user is invited to try this "test" to better determine the speed advantage the analytical solution will provide. The steps to complete this "test" are: 1. Edit the TRAKSAT.DEF file and place ONLY one satellite name under the User Defined area. 2. Run TRAKSAT and select Main Menu option 1 (read in satellite data) and select the satellite name. 3. The next step is to run Main Menu option 4 (delta time mode) from say 4-20-1990 0 UTC for 24 hours by 1 minute steps. (Any date can be substituted.) TRAKSAT Satellite Tracking Program Page 37 4. Answer the prompts to place output into a File of only the Visible passes and Yes to the Ra & Dec question. 5. Use a watch, or a stopwatch to time how long the simulation takes and make a note of the time. 6. Now return to the Main Menu and select the Advanced Features option 0, and press option 1 (User Defined Satellites) and then option 2 or 3 (use the same LOS or Optical visibility test as before). Answer Yes to the question about the same times. The output MUST be directed to a FILE. The program will display how long the analytical solution method took to solve the SAME TIME PERIOD as the delta time mode. The conclusions will be easy to figure out; the Analytical Solution will be some 20+ TIMES FASTER than the Delta Time Mode (OVER THE SAME TIME PERIOD). On the machine used for testing (coprocessor installed) the analytical solution runs about 3 seconds per satellite per 24 hours of simulation time vs. the 120 seconds per 24 hours in the delta time mode. Use the analytical solution for "rough" estimates and the delta time mode for the detailed analysis. The term "rough" implies that the analytical solution is not as accurate as the Delta Time mode, and in fact that is true. The error (Delta Time mode vs. Analytical Solution) is usually LESS then 1 minute for predicted rise or set times. (Remember that the analytical solution will display results for a satellite elevation ABOVE 10 degrees.) The error is the price to pay for the speed advantage. The analytical solution will save the user from "looking" for satellites that will not be seen, or unfavorable passes. That is enough "horn blowing" let us look at an example. Below is and example output from the analytical solution using the screen output option. The visibility method in this example was LOS (line of sight) while the starting date was 4-20-1990 @ 0 UTC hours. The end time was 24 hours. The starting times are entered through the same type method as used in the Delta Time mode. (The time step is NOT used by the analytical solution.) The user is directed to the section on Delta Time mode for further study on entering starting times. The "header" at the top of the display will show some vital information to the user. The tracking station name and satellite data file name along with the visibility method will be displayed to remind the user of the current settings. ****************** * IMPORTANT NOTE * ****************** To change the input file name the user will need to return to the Main Menu and select option 1, and enter the new satellite data file name along with ANY satellite name in that file. (This name will not have any special meaning to the analytical solution.) TRAKSAT Satellite Tracking Program Page 38 (SCREEN OUTPUT OPTION) TRAKSAT Version 2.00 Analytical Solution Tracking Station: HUNTSVILLE, AL File: NASA678.TXT Visibility: LOS Satellite UTC TIME LOCAL TIME AZIMUTH MAX MIN DURATION DATE HR:MN:SC DATE HR:MN:SC ELE RANGE HR:MN:SC Alouette 1 20Apr90 01:08:32 19Apr90 20:08:32 N TO SE 25 1905 00:10:32 20Apr90 02:54:12 19Apr90 21:54:12 NW TO S 43 1387 00:12:12 Cosmos 398 20Apr90 01:19:02 19Apr90 20:19:02 NW TO E 33 1970 00:16:02 20Apr90 03:34:48 19Apr90 22:34:48 NW TO SE 74 2069 00:26:48 20Apr90 05:54:02 20Apr90 00:54:02 W TO S 21 4272 00:23:02 20Apr90 20:54:16 20Apr90 15:54:16 NW TO N 10 1100 00:01:16 21Apr90 01:27:19 20Apr90 20:27:19 NW TO E 39 1879 00:18:19 Starlette 20Apr90 02:27:41 19Apr90 21:27:41 NW TO E 35 1582 00:13:41 Working ... Press Esc to Quit If the Optical method was selected the visibility message will display so. ****************** * IMPORTANT NOTE * ****************** The user can NOT stop/start the screen as in the other modes, i.e., pressing Esc will STOP the display and terminate the analytical solution. This method was chosen to avoid inadvertently waiting for the screen to update while in a pause mode. The screen update can be slow on a Optical visibility test and a NON-coprocessor equipped machine. If a file output was selected the header placed in the file has the same information as the screen header. Below is an example of the analytical solution file output. (The same times as above were used but this example used the optical visibility test.) Below is the screen or file output option menu. ╔═══════════════════════════════════════════════════════════╗ ║ ╔════════════════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ ANALYTICAL RISE & SET ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (F) Output To File ║ ║ ║ ║ (S) Output To Screen ║ ║ ║ ║ LOS Visibility ║ ║ ║ ║ Enter Option (F,S) [F] ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ║ ╚════════════════════════════════════╝ ║ ╚═══════════════════════════════════════════════════════════╝ ****************** * IMPORTANT NOTE * ****************** TRAKSAT Satellite Tracking Program Page 39 The default is to write output to the file TRAKSAT.OUT. This is NOT user selectable, ANY OLD FILES WITH THIS NAME WILL BE OVERWRITTEN. (FILE OUTPUT OPTION) TRAKSAT Version 2.00 Analytical Solution Tracking Station: HUNTSVILLE, AL [ Optical Visibility ] Satellite UTC TIME LOCAL TIME AZIMUTH MAX MIN DURATION DATE HR:MN:SC DATE HR:MN:SC ELE RANGE HR:MN:SC Alouette 1 20Apr90 02:54:12 19Apr90 21:54:12 NW TO S 43 1387 00:12:12 Cosmos 398 20Apr90 01:19:02 19Apr90 20:19:02 NW TO E 33 1970 00:16:02 20Apr90 03:34:48 19Apr90 22:34:48 NW TO SE 74 2069 00:26:48 21Apr90 01:27:19 20Apr90 20:27:19 NW TO E 39 1879 00:18:19 Starlette 20Apr90 02:27:41 19Apr90 21:27:41 NW TO E 35 1582 00:13:41 20Apr90 02:30:13 19Apr90 21:30:13 NW TO E 55 1241 00:13:13 LAGEOS 20Apr90 04:57:34 19Apr90 23:57:34 NE TO W 47 6830 00:51:34 20Apr90 08:22:09 20Apr90 03:22:09 NE TO NW 27 8006 00:40:09 21Apr90 03:34:44 20Apr90 22:34:44 NE TO SW 70 6108 00:56:44 GPS-0001 20Apr90 02:33:52 19Apr90 21:33:52 W TO SE 65 20491 06:47:52 GPS-0002 20Apr90 05:05:15 20Apr90 00:05:15 NW TO NW 13 24419 01:15:15 GPS-0005 21Apr90 02:37:23 20Apr90 21:37:23 W TO SE 65 20533 06:47:23 GPS-0006 20Apr90 00:16:22 19Apr90 19:16:22 NW TO SW 57 20854 04:27:22 SME 21Apr90 02:15:21 20Apr90 21:15:21 S TO NW 29 812 00:05:21 Salyut 7 20Apr90 09:56:11 20Apr90 04:56:11 SW TO NE 71 413 00:06:11 Cosmos 1383 20Apr90 02:53:40 19Apr90 21:53:40 N TO S 50 1293 00:12:40 IRAS 20Apr90 01:52:33 19Apr90 20:52:33 S TO SW 23 1793 00:08:33 The screen below will be displayed when the file output mode is selected and the simulation is over. This case took 423 seconds to complete 112 satellite predictions for 24 hours. ╔═══════════════════════════════════════════════════════════╗ ║ ╔════════════════════════════════════╗ ║ ║ ║ TRAKSAT ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ ANALYTICAL RISE & SET ║ ║ ║ ╠════════════════════════════════════╣ ║ ║ ║ ║ ║ ║ ║ (F) Output To File ║ ║ ║ ║ (S) Output To Screen ║ ║ ║ ║ LOS Visibility ║ ║ ║ ║ Enter Option (F,S) [F] ║ ║ ║ ║ Input File: NASA678.TXT ║ ║ ║ ║ Record# 112 of 112 ║ ║ ║ ║ Total Time: 423 Sec ║ ║ ║ ╚════════════════════════════════════╝ ║ ╚═══════════════════════════════════════════════════════════╝ TRAKSAT Satellite Tracking Program Page 40 ADVANCED FEATURES OPTION 4 To return to the Main Menu the user can press return or option 4. The default will return the user to the Main Menu. NORAD/NASA 2-LINE SATELLITE DATA NORAD maintains general perturbation element sets on all resident space objects. These element sets are periodically refined so as to maintain a reasonable prediction capability on all space objects. In turn, these element sets are provided to users. The input file of current orbital elements can be obtained form several BBS around the country. One such BBS is the Celestial BBS at (513) 427-0674 in Fairborn, Ohio the SYSOP is TS Kelso. See section; Obtaining Satellite Data, for more information on obtaining satellite data. I have included a file of the latest elements for over 120 orbiting satellites. See section; Files Required To Run TRAKSAT. ****************** * IMPORTANT NOTE * ****************** The following was downloaded from Celestial BBS, T S Kelso SYSOP. Effective January 1986, this system began posting the most recent element sets received from NASA/Goddard Space Flight Center for several categories of satellites: Amateur Radio, Earth Resources, Manned Spacecraft, Navigation, Weather, and NASA's 30 Day Specials (which contain objects launched within the last 30 days and are often easy to spot visually). More specifically, these include the following satellites or satellite series: OSCAR, Radio Sputnik, UOSAT, Cosmos, LandSat, SeaSat 1, SPOT, Mir, Salyut 7, Soyuz, LDEF, US Space Shuttle, NAVSTAR (GPS), GOES, Meteor, and NOAA. These elements will be maintained in ASCII format in the file. Data for each satellite will consist of three lines in the following format: AAAAAAAAAAA 1 NNNNNU NNNNNAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN 2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN Line 1 is a eleven-character name. Lines 2 and 3 are the standard Two-Line Orbital Element Set Format identical to that used by NASA and NORAD. The format description is: Line 2 Column Description 01-01 Line Number of Element Data 03-07 Satellite Number TRAKSAT Satellite Tracking Program Page 41 10-11 International Designator (Last two digits of launch year) 12-14 International Designator (Launch number of the year) 15-17 International Designator (Piece of launch) 19-20 Epoch Year (Last two digits of year) 21-32 Epoch (Julian Day and fractional portion of the day) 34-43 First Time Derivative of the Mean Motion (rev/day^2) or Ballistic Coefficient (Depending of ephemeris type) 45-52 Second Time Derivative of Mean Motion (Blank if N/A) 54-61 BSTAR drag term if GP4 general perturbation theory was used. Otherwise, radiation pressure coefficient. 63-63 Ephemeris type 65-68 Element number 69-69 Check Sum (Modulo 10) (Letters, blanks, periods = 0; minus sign = 1; plus sign = 2) Line 3 Column Description 01-01 Line Number of Element Data 03-07 Satellite Number 09-16 Inclination [Degrees] 18-25 Right Ascension of the Ascending Node [Degrees] 27-33 Eccentricity (decimal point assumed) 35-42 Argument of Perigee [Degrees] 44-51 Mean Anomaly [Degrees] 53-63 Mean Motion [Revs per day] 64-68 Revolution number at epoch [Revs] 69-69 Check Sum (Modulo 10) All other columns are blank or fixed. Example: NOAA 6 1 11416U 86 50.28438588 0.00000140 67960-4 0 5293 2 11416 98.5105 69.3305 0012788 63.2828 296.9658 14.24899292346978 For a description of the mean orbital elements see section; What Are The Mean Classical Elements. Note that the International Designator fields are usually blank, as issued in the NASA Prediction Bulletins. All epochs are UTC. Satellites will be ordered by their NASA Catalog Number. The data file will be updated as soon as possible after receipt of new element sets or whenever element sets are received for the Space Shuttle. TRAKSAT Satellite Tracking Program Page 42 The following pages contain a brief overview of the methods used in TRAKSAT and are included to help the reader understand the mechanics of a orbiting satellite about the earth. WHAT ARE THE MEAN CLASSICAL ELEMENTS Five independent quantities called "orbital elements" are sufficient to completely describe the size, shape and orientation of an orbit. A sixth element is required to pinpoint the position of the satellite along the orbit at a particular time. The classical set of six orbital elements are defined as: 1. a, semi-major axis, a constant defining the size of the conic orbit. 2. e, eccentricity, a constant defining the shape of the conic orbit. 3. i, inclination, the angle between the Z axis, i.e. like the North Pole, and the angular momentum vector, h = R X V, i.e. the vector R crossed with the vector V. 4. Ω, longitude of the ascending node, the angle, in the fundamental plane, between the direction of the vernal equinox and the point where the satellite crosses the fundamental plane in a northerly direction, (ascending node). This angle is measured counterclockwise when viewed from the north side of the fundamental plane. 5. w, argument of periapsis, the angle, in the plane of the satellite's orbit, between the ascending node and the periapsis point, measured in the direction of the satellite's motion. 6. T, time of periapsis passage, the time when the satellite was at periapsis. 6a. Sometimes the time of periapsis passage is replaced by the true anomaly, v, the angle, in the plane of the satellite's orbit, between perigee and the position of the satellite at the particular time, t0, called the epoch. * (To convert from T to v) v = (360 deg) * t0 / T TRAKSAT Satellite Tracking Program Page 43 The sharp reader will notice that the NORAD elements do NOT include the semi-major axis, a. It is possible to calculate the semi-major axis with the data in a NORAD elements set. The approach would be; 1. Convert the mean motion into degrees per second. and calculate the time to complete one orbit, this will be called the period. 2. Using the period and the earth's gravitational constant, mu, the semi-major axis can be calculated. (equations used) xn_s = (mean motion * 360)/86400 per = 360/xn_s a = ((per^2 * mu)/(4*π^2))^(1/3) mu = 3.986012d+14 km^3/sec^2. The starting point for the study of motion of one body orbiting another, such as an artificial satellite about the earth, is always the two-body problem; i.e., two point masses attracted to each other according to Newton's Law of Universal Gravitation, the inverse square law. The solution is well-known; the two bodies move about each other in conic sections. For bounded motions, such as those of an earth satellite, this conic is either a circle or an ellipse. The problem can be formulated in different ways, but is always convenient to chose a coordinate system with the origin centered at one of the bodies. The position of the second body then can be specified, for example, by giving its initial cartesian position and velocity coordinates and then integrating the equations of motion to find the future positions and velocities. The cartesian system is not the most convenient one in which to represent the motion because an analytic solution cannot be obtained and the integrations must be done numerically. By adopting a polar coordinate system, one is able to effect an analytic solution referred to above which can be specified in terms of six constants of motion; five orbital elements, a,e,i,w,Ω and the time of pericenter passage T. The last constant can be, and usually is, replaced by the mean anomaly M which is a linear function of time. This is a very convenient way to specify the initial position and velocity of a satellite and it also allows an easy visualization of the motion. The position and velocity of the satellite at any future time can be specified in terms of these six constants, a,e,i,w,Ω,M and time. In realistic applications, such as artificial satellites about the earth, there are forces acting on the satellite in addition to the inverse square force although this is the dominate one. Other gravitational forces are due to distant bodies such as the moon and sun but the principal additional gravitational forces are due to the non-sphericity of the earth. All of the gravitational forces are conservative and can be represented by a potential function. In addition to these extra gravitational TRAKSAT Satellite Tracking Program Page 44 forces, there are non-conservative forces such as atmospheric drag. All of these forces other than the inverse square force are called perturbations. The prediction of motion considering these additional forces is called Perturbation Theory. The orbital elements, constant for pure two-body motion, become slowly varying functions of time when the perturbations are considered. Differential equations describing the time rates of change of the elements are called the Lagrange Planetary Equations, LPE and can be found in any standard book on celestial mechanics. Considering conservative forces only, which can be represented by a potential function, the part of the potential other than the two-body part is conventionally called the disturbing function, represented by R, and the LPE are: . a = 2 / n a * ( δR / δM ) . e = (-(1-e²)^½ / na²e)*δR/δw+(1-e²/na²e)*δR/δM . i = cot i/(na²(1-e²)^½ * δR/δw - δR/(δΩna²(1-e²)½) . w = (1-e²)^½ * δR / na²eδe - cot i * δR/(na²(1-e²)^½)*δi) . Ω = δR/(na² sin i *(1-e²)^½) * δi) M = n - 2δR/naδa - 1-e² * δR/(na²e * δe). * where δ is the partial derivative starting from the very simple representation of the gravitational potential between two point masses of magnitude m0 and mi separated by distance r as; V = -G * (m0 * mi)/r one can, by applying this to a satellite of mass m0 and to every infinitesimal mass point mi of the earth and integrating over the whole earth, arrive at the following potential function for the earth; ∞ n ∞ n m V=-µ/r(1-Σ JnPn (sinδ)(re/r)^ +Σ Σ Jnm (re/r)^ Pn^ (sinδ)cos(m(α-α))). n=2 n=2m=1 mn The first term is the one giving pure two-body motion and the additional terms are the perturbing terms. The first sum, zonal harmonics, represents the flattening and other distortions relative to the equator and the second sum, tesseral harmonics, represents the non-uniformity of the earth in longitude. If, as is frequently done, one assumes that the earth possesses rotational symmetry, then the second sum vanishes. The neglect of the second sum usually produces no noticeable effects except in the case of geosynchronous satellites. Then one must consider those terms which cause slow long-period drifts of the geosynchronous position. TRAKSAT Satellite Tracking Program Page 45 For close earth satellites one can usually take about three terms from the first sum and get very accurate results; even the first term alone will produce very satisfactory results in most cases for short-time periods. The Jn are constants which depend on the mass distribution in the earth and are deduced from analysis of observed satellite motions. The currently accepted values of J2, J3, and J4, which are used in TRAKSAT, are; -3 J2 = 1.082616 X 10 -6 J3 = -2.53881 X 10 -6 J4 = -1.65597 X 10 . The Pn (sin δ) are Legendre polynomials of index n and are even functions of sin δ for n even and odd functions for n odd. The J2 term describes the flattening of the earth and the J3 term the so-called pear shape. J2, which is three orders of magnitude larger than J3, gives rise to secular changes in the elements w, Ω, and M while J3 gives rise to long_period oscillations in e and w. In general, even harmonics cause long-period and secular changes in the elements, and odd harmonics cause long-period oscillations. Short-period oscillations can result from all terms; but since J2 is so much larger than the other coefficients, generally only the J2 short-period terms are considered. Secular terms are those which monotonically increase or decrease with time. For first order solutions this change with time is linear. Long-period terms are those which oscillate with a period of typically one to two months, and short-period terms are those which oscillate with a period of one orbital period or some rational fraction of it. To finish formulating the problem, the disturbing function is expressed in terms of the orbital elements and then the appropriate partial derivatives are taken and substituted into the LPE. One then has a coupled set of first order non-linear ordinary differential equations. Because they are non-linear, they can be solved only by various approximation methods. The usual method is to assume that the solutions can be represented in some type of power series expansion in a small parameter and arrive at sets of approximation equations which can be a close representation of the real motion, at least over short-time periods. The complete solution consists of the sum of the secular terms, short-period terms, and the long-period terms; i.e., a = a + a + a . osc s sp lp TRAKSAT Satellite Tracking Program Page 46 ****************** * IMPORTANT NOTE * ****************** I have NOT included the actual equations used in the program in this document for obvious reasons, i.e. they are long and hard to type in with a text based word processor. If you have an interest in these equations they are in several references I have listed. TRAKSAT Satellite Tracking Program Page 47 MODELS FOR PROPAGATION OF NORAD ELEMENT SETS NORAD maintains general perturbation element sets on all resident space objects. These element sets are periodically refined so as to maintain a reasonable prediction capability on all space objects. In turn, these element sets are provided to users. The most important point to be noted is that not just any prediction model will suffice. The NORAD element sets are "mean" values obtained by removing periodic variations in a particular way. In order to obtain good predictions, these periodic variations must be reconstructed (by the prediction model) in exactly the same way they were removed by NORAD. Hence, putting NORAD element sets into a different model (even though the model may be more accurate or even a numerical integrator) will result in degraded predictions. All space objects are classified by NORAD as near-Earth (period less than 225 minutes) or deep-space (period greater than or equal 225 minutes). Depending on the period, the NORAD element sets are automatically generated with the near-Earth or deep- space model. The PROGRAM will calculate the satellite period and know which PREDICTION MODEL TO USE. THE PROPAGATION MODELS Two mathematical models for prediction are used by TRAKSAT. The first of these, SGP4, was developed by Ken Cranford in 1970 (see Lane and Hoots 1979) and is used for near-Earth satellites. This model was obtained by simplification of the more extensive analytical theory of Lane and Cranford (1969) which uses the solution of Brouwer (1959) for its gravitational model and a power density function for its atmospheric model (see Lane, et al 1962). The next model, SDP4, is an extension of SGP4 to be used for deep-space satellites. The deep-space equations were developed by Hujsak (1979) and model the gravitational effects of the moon and sun as well as certain sectoral and tesseral Earth harmonics which are of particular importance for half-day and one-day period orbits. TRAKSAT Satellite Tracking Program Page 48 COMPATIBILITY WITH NORAD ELEMENT SETS The NORAD element sets are currently generated with either SGP4 or SDP4 depending on whether the satellite is near-Earth or deep- space. For SGP4 and SDP4 users, the mean motion is first recovered from its altered form and the drag effect is obtained from the SGP4 drag term (B*) with the pseudo-drag term being ignored. The value of the mean motion can be used to determine whether the satellite is near-Earth or deep-space (and hence whether SGP4 or SDP4 was used to generate the element set). From this information the program will decide whether to use SGP4 or SDP4 for propagation and hence be assured of agreement with NORAD predictions. TRAKSAT Satellite Tracking Program Page 49 PROGRAM LIMITATIONS AND ASSUMPTIONS The ephemeris equations DO include the zonal harmonics, through 2nd order, of the gravitational potential. This implies a gravitational field produced by an oblate spheroidal earth unsymmetrical with respect to the equator, pear-shaped. In other words, the ephemeris equations contain J2, J3, and J4 terms. The currently accepted values of J2, J3, and J4, which are used in TRAKSAT, are; -3 J2 = 1.082616 X 10 -6 J3 = -2.53881 X 10 -6 J4 = -1.65597 X 10 . The earth equatorial radius used by TRAKSAT is; 6378.135 Km, while the flattening factor used is 1/298.257 (both are from the 1972 WGS models). The program TRAKSAT models only ELLIPTICAL orbital motion about the earth. That is, the orbital eccentricity MUST BE LESS THAN ONE and GREATER THAN ZERO. Very small eccentricities are acceptable, i.e., such as 1.0E - 5. STARS USED IN TRAKSAT The star background option will use the following list of stars for the display. The star data values are from USNO Floppy Almanac 1988, Version 2.11.88, file STAR1.CAT using J2000 coordinates. Bayer Name Proper Name ---------- ----------- Ursae Minoris Polaris Andromedae Alpheratz Phoenicis Ankaa Cassiopeiae Schedar Ceti Diphda/Deneb Kaito Eridani Achernar Arietis Hamal Eridani Acamar Ceti Menkar Persei Mirfak Tauri Aldebaran Orionis Rigel Aurigae Capella Orionis Bellatrix Tauri Elnath TRAKSAT Satellite Tracking Program Page 50 Orionis Alnilam Orionis Betelgeuse Carinae Canopus Canis Majoris Sirius Canis Majoris Adhara Canis Minoris Procyon Geminorum Pollux Carinae Avior Lambda Velae Suhail Carinae Miaplacidus Hydrae Alphard Leonis Regulus Ursae Majoris Dubhe Leonis Denebola Corvi Gienah Crucis ACrux Crucis GaCrux Ursae Majoris Alioth Virginis Spica Ursae Majoris Alkaid Centauri Hadar Centauri Menkent Boötes Arcturus Centauri A Rigil Kentaurus Librae Zubenelgenubi Ursae Minoris Kochab Coronae Borealis Alphecca Scorpii A Antares Triangulii Atria Ophiuchi Sabik Lambda Scorpii Shaula Ophiuchi Rasalhague Draconis Eltanin Sagittarii Kaus Australis Lyrae Vega Sagittarii Nunki Aqilae Altair Pavonis Peacock Cygni Deneb Pegasi Enif Gruis Al Na ir Piscis Austrini Fomalhaut Pegasi Markab METHOD DESCRIPTION FOR REVERSE SOLUTION The reverse solution is a very powerful and useful option for the satellite observer. May times I have looked up to the skies only to see a unknown satellite fly-by. Determining which satellite I saw was almost impossible. The approach I used was to run TRAKSAT in the multi-track mode until I either ran out of satellite data sets or I found a possible match. This could prove very tedious and not very practical on a day to day basis. This "lacking" provided the desire for the reverse solution option in TRAKSAT. The next step was to determine a method to use and what would be required from the user. Several methods of converting observed data into orbital elements TRAKSAT Satellite Tracking Program Page 51 are in use today, such as Gauss, f & g series, Lambert, and true anomaly iteration are just a few. It is difficult to be specifically precise in a statement of which of the previous methods can be termed "the best". Certainly a method which best decrees the problem at hand should be chosen for the determination of a particular orbit. There are, however, several points of interest that should be known to the analyst before choosing a particular method. For example, which method is the fastest from a computational point of view? Which method has the least numerical error? Which method experiences the least convergence difficulties? Numerical studies upon many orbits of varying eccentricity and semi-major axis have provided a very partial answer to these questions. To answer the first question, that is, which is the fastest computational method, several sources were consulted. The fastest method proved to be the true anomaly with the Gauss method following close behind. The f & g series was the slowest method. The second question, which method has the least numerical error, is difficult to answer, and, as might be expected, indicates that every method is optimum in the computation of a particular element. It is, however, possible to segregate the overall results of the numerical studies into three categories: high, medium, and low accuracy. The Gauss and Lambert methods display a high accuracy rating while the true anomaly and f & g series have only a medium accuracy rating. The last question, ease of convergence, is not as difficult to answer. The Gauss and f & g series methods are called "self- perpetuating" in their convergence. That is, from a easily estimated first guess an iterative loop is initiated which converges automatically to the desired result. The Gauss method suffers from instability of convergence for radial spreads of greater than 90 degrees. This should NOT prove a problem because most observed satellite data sets will be viewed in less than a 90 radial spread. The natural conclusion to this analysis was to use the method of Gauss. This document will NOT develop this method as MANY of the references listed go into great detail on the subject. I would suggest the reader to investigate further if interested. ACCURACY OF TRAKSAT Several people have asked the question " How accurate is TRAKSAT ?". To answer such a question one must define a set of limits. The real "acid test" is to have a prediction from TRAKSAT and then go outside and observe that satellite, taking note of the time and position of the satellite. A comparison between actual observed data and predicted can then be determined. Another approach is to compare the output from TRAKSAT against several other satellite tracking programs. Both the public domain and the commercial markets have several good tracking programs that the user could compare with. The later approach, that is the comparison between tracking programs, has been carried out by several people including TRAKSAT Satellite Tracking Program Page 52 myself. The output from TRAKSAT compares very well with many of the "current" tracking programs (both commercial and public domain). It could be concluded from a simple test of TRAKSAT that it agrees with several other tracking programs. The next step is one of comparing predicted output and observed data. The most popular use for TRAKSAT has been in the optical sighting options. The optical sighting of a satellite will be the "acid test" used for this accuracy test. First a note about NASA 2-line elements, low earth satellites (about 15 rev per day satellites) have larger disturbances from the atmosphere than higher satellites. The drag on a satellite can cause purtubations greater than the J2 terms therefore the drag term is of great importance. The very latest elements for the low earth satellite can greatly improve the prediction process, while the higher satellites do not require as current of elements. (The term low will be in the range 250 - 375 kilometers altitude.) Reports about TRAKSAT (and its predictions) have been made on the MIR satellite along with several other low earth satellites. The bottom line being LESS THAN 30 SECONDS ERROR (prediction vs. actual) for 10 day old satellite element sets. If the satellite elements are 20 days old the error is about 60 seconds. If the elements a only a day or two old, errors of less than 10 seconds are possible (several reports have been made about 2-10 seconds of error). The position data is on the money, it is the time at that position that usually drives the accuracy of the observation. The higher earth satellites generally have less than 30 seconds of error for 20 day old elements. A NOTE MUST BE MADE ABOUT THE ERROR ANALYSIS, THE ASSUMPTION IS MADE THAT NO ORBITAL MANEUVERING WAS DONE TO THE SATELLITE DURING THE "TEST" PERIOD. (The STS-31, the Hubble launch, was a prime example of several orbital maneuvers changing the predicted observed times). In general it can be said that the most current elements are the best ones for planning the evenings viewing. (Elements over 30 days old can have a very large error to them). Element sets 7 -14 days old will be acceptable for most users. NORAD/NASA updates the satellite elements for this very reason, the keep the prediction process accurate. TRAKSAT Satellite Tracking Program Page 53 A BRIEF EDITORIAL One of the first decisions to be made when setting out to write a program is the choice of a programming language. I'm an Aerospace Engineer working for a company in Huntsville, Al. My job title is; Trajectory Analysis Engineer. I work with NASA, mostly the shuttle program, and design trajectories for several upcoming shuttle missions. I have written large trajectory simulations programs, for the most part they were written in FORTRAN. I know FORTRAN is not the best language to use for programs that use graphics, but Microsoft has come up with the ideal solution. Microsoft FORTRAN, version 4.0 and higher, can call BASIC, C, and PASCAL routines. Microsoft FORTRAN version 5.0 also contains graphic routines that were used in TRAKSAT, these graphic routines are the same as used in QuickC version 2.0. Most (95%) of the TRAKSAT program is written in FORTRAN to get the best speed and high precision mathematics and C, QuickC version 1.01, for some useful utilities. I have found this combination to be very powerful and useful for writing programs. TRAKSAT Satellite Tracking Program Page 54 SPECIAL THANKS I would like to take this opportunity to thank the many people who helped me either directly or indirectly on this program. First of all my wife, Anita, who understands why I have a hobbie like computers and enjoy working with them. She has not complained about the many hours, in excess of 450 hours, I have spent working on TRAKSAT. TRAKSAT version 2.10 has some 19,000 lines of code and IS STILL GROWING. Dave Ransom Jr., of Rancho Palos Verdes, CA. has kept me going when my interest in the program was slipping away. I did use the city data from his excellent program ASTROCLOCK. I also used several of the references Dave listed in his program. I would highly recommend his program to any person interested in astrodynamics. The documentation supplied with ASTROCLOCK is in itself very interesting reading and very well done. I could only hope that someday TRAKSAT will have that level of professionalism. My thanks to Dave and his wife Vicki. John Williams and Dr. Jeff Wallach, from the Dallas DataLink BBS, have been very helpful in this project also. They have offered data and a helping hand with TRAKSAT. The DataLink BBS has a vast amount of satellite information along with other interests. I would recommend it to others interested in satellite tracking. The DataLink BBS is THE place to learn about obtaining satellite images. I would also like to thank TS Kelso, SYSOP of the Celestial BBS where current satellite data can be downloaded. Several satellite tracking programs are also available on his BBS along with a vast amount of satellite information. James Pattee has helped in the development of TRAKSAT, his "debugging" is most helpful. James is the SYSOP of the Colorado Springs Software Exchange BBS, in Colorado Springs, Co. This BBS has a large amount of software available, however it is NOT a free, at least for full access, BBS. I still recommend this BBS to anyone interested in Astronomy. The latest estimate of the online storage is 1.8 gigabytes (CD-ROM)! TRAKSAT Satellite Tracking Program Page 55 QUESTIONS AND COMMENTS I would very much like to hear from anyone interested in this program and astrodynamics in general. I have not included the source code to TRAKSAT mainly because most people do not have a Microsoft FORTRAN compiler nor a working knowledge of FORTRAN. The high cost ($500.00) of both the FORTRAN and C compilers makes the cost of working on a project like TRAKSAT expensive also. As for the choice of FORTRAN compiliers there are many fine products out and I have used many of them. Lahey, RM make several FORTRAN compiliers that have many features and work very well. However, the only compilier that supports mixed language is Microsoft. For this reason alone I would recommend it to others interested in programming. At this time I feel that TRAKSAT is still going through some "growing pains" and I would like the chance to improve it and add new features. The only way this can happen is if you, the user, takes the time to leave me messages or mail on problems or suggestions. I will try to answer your messages in a timely manor. For the most part I have already received several good ideas and helpful hints for improving TRAKSAT. I would suggest the user to OBTAIN A COPROCESSOR if they do not have one already. A coprocessor speeds up math intensive programs, such as TRAKSAT, to a level that was only dreamed about a few years ago. Please feel free to contact me to discuss TRAKSAT or other computer problems. I can reached through the RPV BBS; RPV BBS Rancho Palos Verdes, Ca. 213-541-7299 24 hours, 2400/1200 baud. This BBS is owned and operated by Dave Ransom Jr.. I call up the BBS once or twice a week to check my mail and do some file transfers. This BBS is geared towards Astronomical interests. The latest version of ASTROCLOCK can be downloaded from this BBS also. Other BBS's I frequent are; Celestial RCP/M DataLink RBBS System Fairborn, Ohio Dallas, Texas 513-427-0674 214-394-7438 24 hours, 2400/1200 baud, 24 hours, 9600/2400/1200 baud. Colorado Springs Software Exchange BBS Colorado Springs, Co. 719-531-6172 24 Hours, 9600/2400/1200/300 Baud. TRAKSAT Satellite Tracking Program Page 56 I can also be reached at work or home, please no calls after 10 PM Central Time. Please leave a phone number and the best time to call on any messages that require by personal attention. The last, and slowest method to reach me is with the U.S. mail service, I will respond with a phone call if at all possible. Paul E. Traufler 111 Emerald Dr. Harvest, Al. 35749 Phone (work) 205-726-5511 Phone (home) 205-830-8450 To obtain the latest version of TRAKSAT, several BBS around the country keep in online. If you would like to save on the long distance charges, contact myself and I will try to find a local BBS that I can upload TRAKSAT to. For a small fee ($10.00) I will mail TRAKSAT on a disk, 360K, 1.2M, if that is the easiest way to obtain the latest version (1.2M is best for me, 3.5 disks are a pain). Please contact the author for more information. IF YOU SEND A SELF ADDRESSED AND STAMPED DISK-MAILING PACKAGE, WITH THE PROPER DISK FORMAT, I WILL RETURN MAIL IT FREE OF CHARGE. TRAKSAT Satellite Tracking Program Page 57 OBTAINING NORAD SATELLITE DATA SETS The following BBS's have the current satellite data files; Celestial RCP/M Fairborn, Ohio SYSOP: TS Kelso 513-427-0674 24 hours, 2400/1200 baud, 8 bit NO parity 1 stop. Datalink RBBS System Dallas, Texas SYSOP: Dr. Jeff Wallach 214-394-7438 24 hours, 2400/1200 baud, 8 bit NO parity 1 stop. Colorado Springs Software Exchange BBS Colorado Springs, Co. SYSOP: James Pattee 719-531-6172 24 Hours, 9600/2400/1200/300 Baud, 8 bit NO parity 1 stop. To obtain the elements from the Celestial RCP/M BBS, (with the least amount of trouble), just dial up the BBS and login. The next step is to type "F" (without the quotes) to go to the Files section, then to area #1. The next step is to type "D", for download and then type "BULLETIN.ARC" as the file to download, open an XMODEM file transfer mode with your telecommunications software. This will transfer the NASA 2-line elements to a file on the users computer. Log out of the BBS and then unarchive the file using several of the unarchiving programs, (PAK, ARC ect.). The downloaded file will have some characters at the top of the file that will need to be removed with a word processor (this MUST save the file in pure ASCII, i.e., PC-Write, Edlin etc. works very well). (This method assumes that an account is available to the user). NASA can provide up to 20 satellite data sets (HARD COPY FORM ONLY) if the user writes and requests them. This service is free but the user will need to enter the elements into a file for use with TRAKSAT. (This is done the old fashion way, you TYPE them!) NASA Goddard Space Flight Center Control Center Support Section Code 513.2 Greenbelt, Md. 20771 TRAKSAT Satellite Tracking Program Page 58 FILES REQUIRED TO RUN TRAKSAT The following files should have been included in the archive file; TRAKSAT.EXE The program. TRAKSAT.DEF The default data for the tracking station. TRAKSAT.CTY The city file for tracking stations. TRAKSAT.DOC TRAKSAT program documentation. EARTH.DAT World map data file. NASA699.TXT This is the latest NORAD satellite data set, (as of May 18, 1990, element set #699). READ.ME Latest notes about the program. MSHERC.COM This utility is used for Hercules graphics. MODERN.FON This is a font file used for the graphics. TRAKSAT Satellite Tracking Program Page 59 BIBLIOGRAPHY THe following sources were used to prepare and test the TRAKSAT program. Meeus, Jean, ASTRONOMICAL FORMULAE FOR CALCULATORS, 3rd Edition, Willmann-Bell, Inc., Richmond, VA. 1985. Duffett-Smith, Peter, PRACTICAL ASTRONOMY WITH YOUR PERSONAL COMPUTER, Cambridge University Press, New York, NY. 1986. Danby, John, FUNDAMENTALS OF CELESTIAL MECHANICS, 2nd Edition, Willmann-Bell, Inc., Richmond, VA. 1988. Bate-Mueller-White, FUNDAMENTALS OF ASTRODYNAMICS, Dover Publications, Inc. New York, NY. 1971. Forsythe-Malcolm-Moler, COMPUTER METHODS FOR MATHEMATICAL COMPUTATIONS, Prentice-Hall, Inc. Englewood Cliffs, NJ. 1977. USAF-Ford Aerospace Corporation, ORBITAL MECHANICS, O&M Training Section, Sunnyvale, CA. 1982. Moulton, F. R., CELESTIAL MECHANICS, Macmillan Company, New York, NY. 1960. Brand, L., VECTOR ANALYSIS, John Wiley and Sons, New York, NY. 1957. Geyling-Westerman, INTRODUCTION TO ORBITAL MECHANICS, Addison Wesley, Whippany, NJ. 1971. Brouwer, D., "Solution of the Problem of Artificial Satellite Theory without Drag", Astronomical Journal 64, 378-397, November 1959. Hilton, C.G. and Kuhlman, J.R., "Mathematical Models for the Space Defense Center", Philco-Ford Publication No. U-3871, 17-28, November 1966. Hoots, F.R., "A Short, Efficient Analytical Satellite Theory". AIAA Paper No. 80-1659, August 1980. Hoots, F.R., "Theory of the Motion of an Artificial Earth Satellite", accepted for publication in Celestial Mechanics. Hujsak, R.S., "A Restricted Four Body Solution for Resonating Satellites with an Oblate Earth", AIAA Paper No. 79-136, June 1979. Hujsak, R.S. and Hoots, F.R., "Deep Space Perturbations Ephemeris Generation", Aerospace Defense Command Space Computational Center Program Documentation, DCD 8, Section 3, 82-104, September 1977. TRAKSAT Satellite Tracking Program Page 60 Kozai, Y., "The Motion of a Close Earth Satellite", Astronomical Journal 64, 367-377, November 1959. Lane, M.H. and Cranford, K.H., "An Improved Analytical Drag Theory for the Artificial Satellite Problem", AIAA Paper No. 69- 925, August 1969. Lane, M.H., Fitzpatrick, P.M., and Murphy, J.J., "On the Representation of Air Density in Satellite Deceleration Equations by Power Functions with Integral Exponents", Project Space Track Technical Report No. APGC-TDR-62-15, March 1962, Air Force Systems Command, Eglin AFB, FL. Lane, M.H. and Hoots, F.R., "General Perturbations Theories Derived from the 1965 Lane Drag Theory", Project Space Track Report No. 2, December 1979, Aerospace Defense Command, Peterson AFB, CO. Bellman, R. and Kalaba, R.E., "Modern Analytic Computational Methods in Science and Mathematics", American Elsevier Publishing Company, Inc. 1967. Escobal, P.R., "Mehtods of Orbit Determination", John Wiley and Sons, New York, NY. 1965.