Package org.orekit.propagation.conversion

Class BrouwerLyddanePropagatorBuilder

java.lang.Object
org.orekit.propagation.conversion.AbstractPropagatorBuilder<BrouwerLyddanePropagator,Orbit,AbstractOrbitFactory<Orbit>>
org.orekit.propagation.conversion.AbstractAnalyticalPropagatorBuilder<BrouwerLyddanePropagator,Orbit,AbstractOrbitFactory<Orbit>>
org.orekit.propagation.conversion.BrouwerLyddanePropagatorBuilder
All Implemented Interfaces:
Cloneable, PropagatorBuilder
public class BrouwerLyddanePropagatorBuilder extends AbstractAnalyticalPropagatorBuilder<BrouwerLyddanePropagator,Orbit,AbstractOrbitFactory<Orbit>>
Builder for Brouwer-Lyddane propagator.

By default, Brouwer-Lyddane model considers only the perturbations due to zonal harmonics. However, for low Earth orbits, the magnitude of the perturbative acceleration due to atmospheric drag can be significant. Warren Phipps' 1992 thesis considered the atmospheric drag by time derivatives of the mean mean anomaly using the catch-all coefficient M2.

Usually, M2 is adjusted during an orbit determination process, and it represents the combination of all un-modeled secular along-track effects (i.e. not just the atmospheric drag). The behavior of M2 is closed to the TLE.getBStar() parameter for the TLE.

If the value of M2 is equal to 0.0, the along-track secular effects are not considered in the dynamical model. Typical values for M2 are not known. It depends on the orbit type. However, the value of M2 must be very small (e.g. between 1.0e-14 and 1.0e-15). The unit of M2 is rad/s².

To estimate the M2 parameter, it is necessary to call the AbstractPropagatorBuilder.getPropagationParametersDrivers() method as follows: 

  for (ParameterDriver driver : builder.getPropagationParametersDrivers().getDrivers()) {
     if (BrouwerLyddanePropagator.M2_NAME.equals(driver.getName())) {
        driver.setSelected(true);
     }
  }
Since:
11.1
Author:
Melina Vanel, Bryan Cazabonne