PartialDerivativesEquations with drag
I'm having problems getting proper values for the partial derivatives when I use drag. For example, with the orbit:
initialDate = new AbsoluteDate(2004, 1, 1, 0, 0, 0., utc);
frame = FramesFactory.getEME2000();
rpe = 160.e3 + Constants.WGS84_EARTH_EQUATORIAL_RADIUS;
rap = 2000.e3 + Constants.WGS84_EARTH_EQUATORIAL_RADIUS;
inc = FastMath.toRadians(0.);
aop = FastMath.toRadians(0.);
raan = FastMath.toRadians(0.);
mean = FastMath.toRadians(180.);
mass = 100.;
with drag sensitive model:
shape = new SphericalSpacecraft(10., 2.2, 0., 0.);
with only central gravity and drag with an atmosphere like:
itrf = FramesFactory.getITRF(IERSConventions.IERS_2010, true);
earthShape = new
OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
Constants.WGS84_EARTH_FLATTENING, itrf);
atmosphere = new SimpleExponentialAtmosphere(earthShape, 1.225, 0.,
10.e3);
I get the following output:
Date: 2004-01-01T01:30:00.000
Position: {-5.660.489,6267137285; 4.344.167,136662178; -0,0157272603}
Velocity: {-4.619,9271992409; -5.684,5181628524; 0,00019987}}
If I modify the initial state vector by [1,0,0] meters, I get the following output:
Date: 2004-01-01T01:30:00.000
Position: {-5.660.491,824812218; 4.343.719,247031297; -0,0156442088}
Velocity: {-4.619,658578403; -5.684,9851595053; 0,0001998725
The difference in position should "roughly" match the first column of the transition matrix. Nevertheless, when I print the first column of the transition matrix I get:
Date: 2004-01-01T01:30:00.000
0 0 -7.0653777029246445
1 0 -10.191949814707023
2 0 4.925220784874132E-6
3 0 0.010585100903880132
4 0 -0.008159254840044813
5 0 -5.599845981535752E-9
which is very different from the difference of state vectors. Could you please see if you can reproduce this behaviour? Can you give an explanation for that?
Thanks!
(from redmine: issue id 229, created on 2015-12-23, closed on 2016-02-10)