Generating Prelaunch Elsets (Was: STS88 and ISS)

Ron Lee (
Wed, 06 Jan 1999 19:49:17 -0700

>Ron Lee, you and some others, including Mike McCants, Rainer Kracht, Ted 
>Molczan, (I'm probably forgetting some important names here, I recall 
>Alan Pickup and Bjorn Gimle having done so for decaying objects), have 
>displayed a wonderful ability to generate elsets for anticipated, i.e., 
>powered, flights.  Is it possible you could teach me to do that for 
>shuttle operations?  Or possible that someone would be interested in doing 
>it and posting the results here?  To communicate with the Cleveland and DC 
>media, I need roughly 1-minute accuracy roughly 4 or 5 days in advance. 
>I'm quite willing to cope with numerous updates occasioned by 
>unanticipated changes in the operational schedule, but when they occur, I 
>need either  a) to know how to munge the elsets back to life, or  b) new 
>elsets.  (Those of you who are doing the same thing for your own local 
>media may not need quite so much lead time).  I need the same lead time 
>for reboosts and the like. 

My abilities are somewhat limited in that I do not always catch obvious
errors in reported data.   My Iridium elsets have enjoyed a reasonable
accuracy because I use previous early orbit elsets and adjust the new launch
for the date and time using a program called ADJ2LINE.  I then run STSPLUS
to verify that the orbit plane is about right and the SV is in the correct
location.  This does not always work because they sometimes use different
launch profiles.

For other launches, where Keith Stein graciously provides launch data, I take
the data and plug it into a program called MAK2LINE which generates a two-line
element set. I then run it in STSPLUS at the epoch time to see it it looks
reasonable and compares with the longitude and latitude provided.

I have not yet learned how to generate or modify elsets from observations
like the other folks you mentioned are able to do.  I have settled into
a teeny weenie niche where I can provide some useful info.   A few folks
have been able to see early orbits and in one case a fuel venting in part
due to my elsets so I help others a little.

Since I am getting a few people to read this, I will make my annual plug
for info on orbit burns. There are a lot of apogee burns for GEO SVs.
My gola is to some day see such an event but it really helps to know
when the burn will occur. Yes I know it is at apogee but I prefer to not
have to go out and observe every apogee just in case...especially when 
it is cold.  So if there is any way to obtain such info, I would appreciate
the data.

Ron Lee