heyoka.model.eo_dynamics

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heyoka.model.eo_dynamics#

heyoka.model.eo_dynamics(*, max_geo_degree: int = 0, max_geo_order: int = 0, eop_data: eop_data = eop_data(), sw_data: sw_data = sw_data(), iau2006_thresh: float = 1e-3, Cb: expression | None = None, elp2000_thresh: float | None = None, vsop2013_thresh: float | None = None) → list[tuple[expression, expression]]#

Formulate the dynamics of an Earth-orbiting spacecraft.

Added in version 7.11.0.

The dynamics is formulated in terms of the Cartesian state variables [x, y, z, vx, vy, vz] in the GCRS, with distances measured in kilometres and time in TT seconds since the epoch of J2000.

The precise formulation of the dynamics is controlled by several (optional) keyword arguments. By default (i.e., if no arguments are passed in input), purely Keplerian dynamics is returned, with the Earth’s gravitational parameter taken from get_egm2008_mu().

Currently the dynamical model includes:

  • geopotential via the EGM2008 model,

  • atmospheric drag via the NRLMSISE-00 model (enabled if the Cb argument is provided),

  • third-body perturbations via the ELP2000 and VSOP2013 analytical theories (enabled if both the elp2000_thresh and vsop2013_thresh arguments are provided).

The eop_data argument is used in the formulation of the Earth’s gravity and of the atmospheric drag. The sw_data argument is used in the formulation of the atmospheric drag. The threshold arguments iau2006_thresh, elp2000_thresh and vsop2013_thresh control the precision of the analytical theories used in the formulation of the dynamics. Please refer to the Earth-orbit dynamics section in the documentation for a quantitative analysis of how these threshold affect the accuracy of numerical integration.

Parameters:

  • max_geo_degree – the maximum geopotential degree.

  • max_geo_order – the maximum geopotential order.

  • eop_data – the Earth orientation parameters data.

  • sw_data – the space weather data.

  • iau2006_thresh – the truncation threshold for the precession-nutation model.

  • Cb – the ballistic coefficient of the spacecraft, in m**2/kg. If not provided, atmospheric drag is disabled.

  • elp2000_thresh – the truncation threshold for the ELP2000 theory. If not provided, third-body perturbations are disabled.

  • vsop2013_thresh – the truncation threshold for the VSOP2013 theory. If not provided, third-body perturbations are disabled.

Returns:

the differential equations for the state variables [x, y, z, vx, vy, vz].

Raises:

ValueError – if one or more input arguments are malformed.

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