SatEvo v0.52        (SatEvo v0.52 released 2012 July 12)
============        (Readme updated in 2016 by @DutchSpace)

Basic operation
---------------

Running the program brings up a prompt for the name of the
element file to be read. 
This may be any text file containing elsets in "tle" format - SatEvo will search the file for all the elsets it contains (it is not fussy about checksums on input).

For every elset SatEvo finds, it will compute a decay date for the object and it will report this on the screen it it falls within 1,000 days of the epoch of the elset. 
If any objects are predicted to decay within this period, SatEvo also creates a file in the same directory as the input file. This file, with the same name as the input file but with the filename extension ".dk", contains a copy of the screen output from this phase.

If a single decaying object is identified, you are next prompted 
for the filename for the orbital evolution. 
This evolution continues for 30 days, or until decay, whichever comes first.

If multiple decaying objects are identified, you are prompted
for the elset number of the one you wish to evolve and, as before, for the name of the output file for the evolution. 
After this file is created, you may select another elset for evolution, and so on until you enter an elset number of zero.

More advanced operation
-----------------------

To control aspects of the operation of SatEvo, UNIX-like 
flags/parameters may be provided on the command-line by which the program is invoked. 
In addition, the name of the input element file may also be provided on the command line. 

Overview of possible flags/parameters:

-LDays Lifetime flag. The default operation is for SatEvo to report the expected decay date if it falls within 1,000 days of the elsetepoch. 
Inserting, for example, "-L5002" on the command line will
instruct SatEvo to report decays which occur within 5,002 days of the elset epoch.

-PDays Prediction limit. By default, SatEvo evolves a selected orbit for 30 days or until decay, whichever comes first. 
A command-line entry of, for example, "-P4.5" will end the evolution after 4.5 days rather than 30 days.

-Qn.nnnn Q-factor. This experimental facility allows the internal quantity Q to by varied by the factor provided. If not given, the factor defaults to 1.0. For a given input elset, the act of changing the Q-factor is to change the predicted lifetime by the same factor.

-Fnnn Solar flux flag. This allows the user to specify the prevailing solar flux (the F10.7 index). The default value is 150, but this is inappropriate near times of sunspot minimum.

-Sn Object Size in m. 

-Tn Shift in transition region (km)

-Hn Supply scale height factor 

-E Create Equator crossing file

-D Provide base/root directory for orbital element sets (-Dd:\Sats_db\db\)

Flags may be combined in any order.

Release history
---------------
v0.21 (1996 Oct)    A few copies distributed at Eurosom 2 in Belgium.
v0.22 (1996 Dec 31) Corrected bug in header line when the latter 
     		    is constructed using the international designation 
	     	    from line 1 of the input tle.
v0.23 (1997 Jan 9)  Append "km" to apogee/perigee heights.
v0.24 (1997 Jan 11) Check n is valid in elinput.
v0.25 (1997 Jan 26) Allow command line flag -Q and filename.
v0.26 (1997 Mar 9)  Additional cmd line flags -L and -P.
v0.27 (1997 Mar 14) Bugfix: check on lifetime within limit reintroduced.
v0.28 (1997 Mar 18) Allow 6 chars for element number in decay list
                    and change variable from _int to _long.
v0.29 (1997 Aug 2)  Insert leadzeroes on dates from 2000.
v0.51 (2008 Jan 21) specify the prevailing F10.7 solar flux
		    and corrects a bug in the reading of epochs in 2008 and 2009.
		    Solaris version no longer provided, replaced by Linux version.
v0.52 (2012 Jul 12) Changed to LCC compiler (.dll no longer needed) Updated e-mail
		    Linux version no longer provided.

Acknowledgements
----------------

I thank Russell Eberst and Mike McCants for encouragement and
assistance during my writing of SatEvo.

Comments on this program are invited via email to me at 
                  alan@astrowatch.org

The current version of SatEvo is available via @DutchSpace server here:
                  http://satevo.p3s.nl

Alan
-- 
 Alan Pickup | COSPAR site 2707:   55d53m48.7s N   3d11m51.2s W    156m asl
 Edinburgh   |
 Scotland    |