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1992-11-20
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ORBITAL ELEMENT UTILITIES
BY LAWRENCE BALDWIN
NOVEMBER 20, 1992
ORBITAL ELEMENTS UTILITIES (OEU) is used to create, update, check and perform
various functions with orbital elements and orbital element files. I do not
guarantee that somewhere along the line the user will not run into some type of
trouble. I recommend that all files have a backup made before using OEU on
them. I have included a file called ELEMENTS.TXT for you to practice on before
you begin to use OEU on your own elements. If you do have any problems,
comments or suggestions, please write me so I can make changes to improve OEU.
Lawrence Baldwin
9303 Fiesta Way
Louisville, Ky. 40272
WHAT ARE ORBITAL ELEMENTS?
--------------------------
Orbital Elements are issued by many sources to be used with
satellite tracking programs. These are two lines that contain
data such as Epoch, Decay Rate, Inclination, etc. about a
satellite.
Orbital elements look like the example below that was for the
Russian Mir Space Station.
1 16609U 86 17 A 92156.77600283 0.00007728 00000-0 77143-4 0 7802
2 16609 51.6000 308.9681 0023779 131.7850 228.5533 15.56653988360344
OEU does require each set of orbital elements to have a satellite
name attached to them in this format below (also review file
ELEMENTS.TXT).
MIR
1 16609U 86 17 A 92156.77600283 0.00007728 00000-0 77143-4 0 7802
2 16609 51.6000 308.9681 0023779 131.7859 228.5533 15.56653988360344
If yours does not have a name in this format you will need to add
a name for each satellite by using an editor or word processor.
Most satellite tracking programs do not require NDDOT 6, Bstar, or
Ephemeris Type numbers (spaces 45-63 in elements line one) to
make them function. Due to this and to allow space for other
data, none of the utilities in OEU will use these numbers. If you
do need to use this data, again you will have to add the NDDOT 6, Bstar
and Ephemeris data by using an editor or a word processor.
WHERE TO RECEIVE ORBITAL ELEMENTS
---------------------------------
Orbital elements can be received from many sources. Many can be received over
various Bulletin Board Systems. Here is a small list of BBS's that operate 24
hours a day.
For orbital elements for shuttle missions that are in progress:
Spacelink, operated by the Marshall Space Flight Center in Huntsville, Alabama
1-205-895-0028
Johnson Space Flight Center, Houston, Texas, 1-713-483-2419
For all types of satellites:
RPV Bulletin Board System, Rancho Palos Verdes, California, 1-310-541-7299
Celestial BBS, Dayton, Ohio 1-513-427-0674
Orbital Information Group BBS operated by the Goddard Space Flight Center
1-301-306-0010, 0011, 0012, and 0013
If you don't have access to a modem for your computer, orbital elements can be
obtained through the mail from the Goddard Space Flight Center. First you need
to obtain a copy of the Satellite Situation Report that is published quarterly.
This is due to the fact that satellites must be ordered by their catalog number
that is given in the report. The satellite report can be received by writing:
Office of Public Affairs (Code 130)
NASA Goddard Space Flight Center
Greenbelt, Maryland U.S.A. 20771
When you have decided what satellite orbital elements you want to receive, send
your list with the satellite's name and catalog number to:
Project Operations Branch (Code 513)
NASA Goddard Space Flight Center
Greenbelt, Maryland U.S.A. 20771
********************************
** ORBITAL ELEMENTS UTILITIES **
********************************
NOTE: ALL FILES THAT ARE ACCESSED BY OEU MUST RESIDE IN A DIRECTORY.
ORBITAL ELEMENTS MENU
---------------------
The ORBITAL ELEMENTS MENU (filename UTILMENU.EXE) only serves one purpose, and
that is to tie all the programs together. Each program can be executed
separately but, when you exit that program it will return to the ORBITAL
ELEMENTS MENU.
ORBITAL ELEMENTS EDITOR
-----------------------
The EDITOR is used to update existing files and create new files. The EDITOR
will first display a screen asking for the directory, file name, and disk drive
that the file you want to edit resides in. If this file is not found when
exiting EDITOR, this file will be created.
NOTE: EDITOR WILL ONLY HOLD 200 SATELLITES IN A FILE. IF MORE THAN 200 RESIDE
IN A FILE, YOU WILL NEED TO USE 'CONVERTER' TO BREAK THE FILE DOWN.
Once the above information is entered, EDITOR will display its main menu.
There are five functions on this screen: 1. ADD NEW SATELLITE, 2. UPDATE A
SATELLITE, 3. DELETE A SATELLITE, 4. CREATE MULTIPLE FILE DUMP, <ESC> EXIT
SYSTEM. Let's look at each function separately.
1. ADD A SATELLITE
------------------
When you press <1> from the EDITOR's main menu, you will be taken to where new
satellites that don't exist in a file are added. Notice at the top of the
screen that an example set of orbital elements is displayed. This display will
show you, as you enter your orbital elements where the information is located
if you are reading your elements from a printed list. As you go down the list
on the screen to enter your data, two arrows will show you where this data
starts and stops in the element line. There will not be any arrows displayed
when the satellite's name is asked for.
Once all data is added, you will be asked if you want to add another satellite
or not. Make your choice with a 'Y' for yes and an 'N' for no. If 'N' is
entered, then the user will be taken back to the main menu.
2. UPDATE A SATELLITE
---------------------
When <2> is pressed from the main menu, the user will be taken to the area
where elements for satellites are updated. The first screen will display all
the satellites that are in your file with 15 satellites to a screen. If there
are more than 15 satellites in your file just press any key to scroll through
the list or press <ESC> to interrupt the scroll.
Notice on the left of the screen that there will be a number next to the
satellites' names. This number is used to pick the satellite that you want to
update. Let's say you want to update the Hubble Space Telescope and the number
on the left of it is 24. When you have reached the end of your file, you will
be able to enter this number to bring up the elements for Hubble.
When the elements screen is displayed, you will notice the elements display at
the top of the screen (See 1. ADD A NEW SATELLITE above for description) and
all the orbital elements for your selected satellite. You can pick separately
each element that you want to update by entering its number at the prompt at
the bottom of the screen. Let's say you want to change the epoch date. This
is done by entering the number 7 at the bottom of the screen where it will ask
you next to enter that data. When <ENTER> is pressed the update screen will
be updated.
On updating the satellites name by entering <1>, you have a option to do two
things, 1. update the satellite's name or 2. enter an asterisk (*). If an
asterisk is entered, the name is not updated but the asterisk is attached to
the end of the satellite's name. This is to indicate that the satellite has
re-entered the earth's atmosphere. When you leave the element screen by
pressing <ENTER> with no entry at the prompt, you will be taken back to the
selection screen for another selection. If you entered an asterisk on any
satellite, on the right side of the screen, that satellite will display
'RE-ENTERED EARTH'S ATMOSPHERE.'
If you decide not to select another satellite and to return to the main menu,
just press <ENTER> with no entry at the prompt when you reach the end of the
list.
3. DELETE A SATELLITE
---------------------
When <3> is pressed from the main menu the user is taken to the area where
satellites are deleted from the file. There will be a flashing 'DELETING FILE'
message at the top to let you know that you have entered this area of the
program. To delete the satellite that you want enter the number to the left of
the satellite's name when prompted. If for some reason you have entered this
area by mistake and do not want to delete any satellites just press <ENTER> by
itself at the prompt, and you will return to the main menu screen without any
satellites being deleted. After each satellite is deleted from the file the
user will be taken back to the main menu.
4. CREATE MULTIPLE FILE DUMP
----------------------------
Most people that track satellites will use the same elements in more than one
tracking program. The MULTIPLE FILE DUMP option is to let a user that has
updated an element file from one program, copy it to other programs as well.
For example, let's say that you have updated a file in program STSORBIT and
when you save the file, you would also like for it to go to STSPLUS and to PC-
Track. This is what MULTIPLE FILE DUMP is all about. You will be able to save
one file update to as many as 15 other programs. The key thing you need to
know is where each program that the file will be saved to is located in your
system (directory, program name and disk drive).
When you press <4> from the main menu, a display screen of all 15 paths is
displayed. Notice in the first path that the file that you originally enter at
the very first screen to update or create a file is listed there. This is so
it will be updated or created when you exit EDITOR.
To add a path that sends your file to a certain program, you must know the
directory, file name and disk drive that the program resides in. Let's say
that we want to save our file to the program, STSPLUS, that resides in
directory, SPACE, of disk drive 'C', and we want that file to be called
ELEMENTS.TXT. You will enter at the PATH prompt at the bottom of the screen:
C:\SPACE\ELEMENTS.TXT
When <ENTER> is pressed, the path name will be entered in the next available
path slot.
If you would like your file saved to a path with the same name as the file that
you loaded into EDITOR, enter as the file name '*.*'. For example; we loaded
in a file named ELEMENTS.TXT and would like that same name added to the program
STSPLUS when it is saved. Your path entry will look like this:
C:\SPACE\*.*
To delete a path, just enter the path number in the PATH prompt at the bottom
of the screen. When enter is pressed, that path will be deleted and all
remaining paths will move up one slot.
To exit from MULTIPLE FILE DUMP, just press <ENTER> without entering anything
in the PATH prompt. All your paths that you have entered into EDITOR will then
be saved to a file called PGMSTORE.TXT. Each time that a file is saved, EDITOR
will read PGMSTORE.TXT, and save all files to these programs until PGMSTORE.TXT
is updated once again.
<ESC> EXIT SYSTEM
------------------
Press <ESC>, and EDITOR will begin creating your orbital elements and then will
return to ORBITAL ELEMENT UTILITIES MENU. During the creation of the orbital
elements, it will save your file to all programs that were specified in the
MULTIPLE FILE DUMP. It will also calculate new check sum numbers for each line.
Since we did not use NDDOT 6, Bstar and Ephemeris data, the check sum numbers
would have changed. If EDITOR did not update these numbers your file could
cause some programs to crash when used.
ORBITAL ELEMENT CHECKER
-----------------------
CHECKER is used to check orbital elements for the most common errors that may
exist. This could be bad check sum numbers, lines longer or shorter than 69
characters, digits where spaces should be and decimal points out of place. If
you down loaded your elements from a Bulletin Board System its recommended that
you use CHECKER. NASA has been known to send out elements with bad formats.
Since you may not run across any errors in any orbital elements for sometime
(maybe never), I have encluded a file call WRONG.TXT that you can check to see
how CHECKER works.
By pressing <2> from the ORBITAL ELEMENT MENU the user is taken to ORBITAL
ELEMENT CHECKER. CHECKER consists of only one screen. You will be asked to
enter the directory, file name and disk drive of where the file that you wish
to check resides.
Next, you will be asked if you want a detailed print out. If this option is
answered as 'Y' (yes), make sure that your printer is turned on. This will
print out a detailed description of what is wrong with your orbital elements if
anything.
When <ENTER> is pressed, CHECKER will begin checking your file. It will
display each satellite as it is checking it. For a file with about 700 or more
satellites in it, it may take a minute or two depending on the speed of your
system. When CHECKER is finished checking your file, it will display a small
summary of what was wrong. It will show you how many satellites were checked,
the number of check sums that were updated, how many elements that were not 69
characters long, how many spaces in a line had digits in them, and how many
decimal points were out of alignment.
CHECKER will only update the check sum numbers if it is wrong. Other errors
that may be found are not updated. This is so the user can determine which
data is good and which is not, and make the necessary changes.
If the user wishes to do another check of a file, they should press <ENTER>.
All prompts will default to the previous settings except for the detail print
out.
To exit checker press <ESC>.
If for some reason that you would like to have your original file back, CHECKER
has renamed it as OLDCHECK.TXT and you will find it in the directory of the
file that you were checking.
ORBITAL ELEMENT SELECTOR
------------------------
If a user has a large file and would like a few of the satellites in it in a
file by themselves then SELECTOR will do the job easily. For example you have
a file with over 700 satellites in it and you would like Mir, Hubble Space
Telescope and the Gamma Ray Observatory by themselves in one file.
Press <3> from the ORBITAL ELEMENTS UTILITIES MENU, and the user will be
brought to SELECTOR. The user will be asked for the directory, file name and
disk drive in which the main file is located. Next, give a name for the file
that you will be putting your satellites into. The main list of satellites
will begin to scroll. Notice on the left that each satellite has a number.
When selecting the satellite that you want, enter this number into the prompt
at the bottom of the screen, and it will add it to your new file. To continue
scrolling through the file, just press <ENTER>. To end the scrolling at
anytime, just type 'END' into the prompt and you will be given two options, 1.
restart SELECTOR or 2. exit SELECTOR. Press <ENTER> to restart SELECTOR and
press <ESC> to exit and return to ORBITAL ELEMENTS MENU.
ORBITAL ELEMENTS CONVERTER
--------------------------
CONVERTER will break down large files into smaller files. EDITOR will only
hold 200 satellites at one time, so a file that is larger than 200 needs to be
broken down.
CONVERTER will first ask for the directory, file name and disk drive that the
file that needs to be broken down resides in. Next, the user will need to give
the broken down files a name. Then CONVERTER will ask for the number of
satellites that you would like in each file. When this number is reached,
CONVERTER will begin building a new file. It will use the name that you
entered but will change the file extension to 001 , 002 and so on. CONVERTER
will next ask for the minimum and the maximum of the inclination of the
satellites. This is for building a file of satellites that falls within a
certain range.
Once this information is entered, CONVERTER will begin to break down the files
into smaller ones with the number of satellites and inclination ranges that you
specified.
When CONVERTER is finished, just press <ENTER> to return to ORBITAL ELEMENTS
MENU.
ORBITAL ELEMENT FINDER
----------------------
FINDER is used to find a certain satellite in a large file and view its
elements. Finder will first ask you for the directory, file name and disk
drive in which the file that you are searching for resides in. You will next
enter the satellites' name or its catalog number. When entering the name, you
can enter it in either upper or lower case letters. If you would like to view
all satellites that have the first few characters in common, enter those
characters only. If a satellite is found, it will be displayed. Press <ENTER>
to begin the search process again. Press <SPACE BAR> to continue the current
search or <ESC> to end FINDER and return to ORBITAL ELEMENTS MENU.
ORBITAL ELEMENTS VIEWER
-----------------------
VIEWER will display an entire element file. Just enter directory, file name,
and disk drive that the file is in. You can view the whole file and continue
from page to page by pressing any key, and stop at anytime by pressing <ESC>.