Problem Need help, setting up launch scenarios.

[Donamy]

I'm having a problem setting up a historic STS launch scenario. First I set the UT date and time, to the corrisponding flight T-30 sec. Then I paste the elements from a saved scenario that had the ISS directly over the Cape. I would think this would work, but when I start the scenario, the ISS is no where near the position it should be. Can anyone enlighten me to what I'm not gettting?

 

[tblaxland]

Then I paste the elements from a saved scenario that had the ISS directly over the Cape.

How far off in date is the original scenario? The elements have an epoch associated with them (the last term IIRC) and Orbiter will propagate those elements from the element epoch until the scenario epoch using Keplers equation. Even just changing the epoch will not work because Earths rotation and movement around the sun will be different from the epoch of the original elements.

I recommend getting the historic TLEs from Celestrak and importing them using the TLE Scenario Editor. Set the date in the scenario before you import the TLEs. I've found the LAN (in geocentric coordinates) may still need to be tweaked a little to get the proper plane alignment since I've foun them to be out a bit.

Another option is to see if Daveid413 has a launch scenario for that mission. His state vectors are generally very good but remember that the vectors are only valid for the epoch of the scenario you find them in.

The state vectors from JPL Horizons are not very good for ISS historical purposes, in my experience, so I don't recommend that source.

Also, be aware that the launch time should be offset (increased) by approx 65s (some adjustment may be required to that number depending on the date of your scenario and how many leap seconds there have been since then).

Things were discussed with Bloodspray here previously for an STS-120 scenario he was doing: http://www.orbiter-forum.com/showpost.php?p=119852&postcount=50