On 14 Nov 2014, at 23:43 , paulcefo <paulcefo@buffalo.edu> wrote:
Matt,
There is a well established way to do this.
1. you should use the state vector as the initial condition in a
Special Perturbation (numerical integration) orbit propagation. If
you are considering a LEO orbit, the time interval for the Special
Perturbation orbit propagation should be at least 3 or 4 days. You
should record the position velocity on a fine grid (say every few
minutes).
The 3 or 4 day interval is dictated by the desire to make the
integration span long relative to the periodic terms that are
neglected in the GP4 theory that is the basis for the TLE.
2. use a least squares process (differential correction) to fit the
GP4 theory to the position and velocity that you created with the
Special Perturbation orbit propagator.
The results of this least squares process will a set of TLE.
There are lots of fine details to be discussed.
There are documents and software that describe and demonstrate this
approach.
The DSST satellite theory is quite ... different ... from GP4.
Send me a note and we can discuss.
regards,
Paul Cefola
--
Dr. Paul J. Cefola
Consultant in Aerospace Systems, Spaceflight Mechanics, &
Astrodynamics
Adjunct Faculty, Dept. of Mechanical and Aerospace Engineering,
University at Buffalo (SUNY)
4 Moonstone Way
Vineyard Haven, MA 02568
USA
508-696-1884 (phone on Martha's Vineyard)
978-201-1393 (cell)
paulcefo@buffalo.edu
paul.cefola@gmail.com
On 11/14/2014 3:01 pm, matthew.darden@solers.com wrote:
Hi,
I have to take a state vector (in this case a PVCoordinates and
AbsoluteDate)
and convert it into a TLE (or rather orbital elements that I can
make a TLE
from). I know the answer will never be very good, but I have to do
it. Is
there a good way to make this conversion?
I know that I can just get what I need by creating a
KeplerianOrbit from what
I have, but those values are osculating and I need the mean
orbital elements
if I want the answer to be anywhere near correct. I tried using
OsculatingToMeanElementsConverter with a DSST propagator using
different force
models, but nothing really made any difference.
As a test case I took a random TLE, got the PVCoordinates at the
time the TLE
was created (so that it would be as accurate as possible) and
passed those
into my method. Which should spit out a generic TLE with orbital
values close
to the originals. To test how close the two orbits truly are, I
simply
propagated them both every 10 minutes for a 24 hour period,
checking the
distance between the two points.
Thank you,
Matt