Hello everyone,
Probably I’m missing something relevant but I want to include drag in the Brouwer Lyddane propagator.
My code reads a TLE and then, it constructs the initial orbit as keplerian in order to propagate it with BL propagator. My entire code is:
# Orekit initialization
import orekit
vm = orekit.initVM()
from orekit.pyhelpers import setup_orekit_curdir
setup_orekit_curdir()
# Import needed functions
from org.orekit.propagation.analytical.tle import TLE, TLEPropagator
from org.orekit.propagation.analytical import BrouwerLyddanePropagator
from org.orekit.orbits import OrbitType
from org.orekit.utils import Constants
# Select the TXT file
TXTName = "C:/Users/veron/Desktop/TLEs/AGILE.txt"
# Read the TLE from the selected .txt file
TXTFile = open(TXTName, mode="r")
desiredtime = TXTFile.readline()
tle1 = TXTFile.readline()
tle2 = TXTFile.readline()
TXTFile.close()
# Create the TLE object
mytle = TLE(tle1, tle2)
# Get the keplerian orbit from the TLE
tle_propagator = TLEPropagator.selectExtrapolator(mytle)
tle_orbit_cart = tle_propagator.getInitialState().getOrbit()
tle_orbit_kep = OrbitType.KEPLERIAN.convertType(tle_orbit_cart)
# Propagation with Brouwer Lyddane Propagator
propagator_eh = BrouwerLyddanePropagator(tle_orbit_kep, Constants.EIGEN5C_EARTH_EQUATORIAL_RADIUS,
Constants.EIGEN5C_EARTH_MU, Constants.EIGEN5C_EARTH_C20,
Constants.EIGEN5C_EARTH_C30, Constants.EIGEN5C_EARTH_C40,
Constants.EIGEN5C_EARTH_C50, 0.)
end_state = propagator_eh.propagate(mytle.getDate(), mytle.getDate().shiftedBy(float(desiredtime) * 60))
As far as I know, the final input value of the BrouwerLyddanePropagator function is the M2 value (set above to 0.), but I want to consider the drag effects. How can be the M2 value computed?
Many thanks in advance,