GravityEngine2.SGP4Propagator Class Reference

Code to propagate SGP4 satellites i.e. satellites in Earth orbit with modeling for atmosphere, oblate gravity, moon, sun etc. More...

Classes
struct	PropInfo

Static Public Member Functions
static bool	Evolve (double tSec, ref NativeArray< PropInfo > propInfo, int i, ref GEBodyState state, double scaleLtoKm, double scaleKmsecToV, double startTimeJD)
	Evolve an SGP4 propagator to a given time.
static bool	EvolveAll (double tSec, ref GEPhysicsCore.GEBodies bodies, ref NativeArray< PropInfo > propInfo, in NativeArray< GEPhysicsCore.PatchInfo > patchInfo, in NativeArray< int > indices, int lenIndices, double scaleLtoKm, double scaleKmsecToV, double startTimeJD)
	GE entry point, to evolve a set of SGP4 bodies as defined by the indices index list.
static void	ManeuverPropagator (int bodyIndex, double tSec, double timeJD, ref GEPhysicsCore.GEBodies bodies, ref NativeArray< PropInfo > sgp4Props, double scaleLtoKm, double scaleKmSecToV)
	Change the state of an SGP4 propagator from a maneuver. Current r, v have been updated, so re-calculate the SGP4 state. Blend the result back to the current SGP4 state over a short period, typically 2% of the orbit period.
static PropInfo	ReInit (double tSec, double timeJD, double3 rKm, double3 vKm, Orbital.COE coeKm, ref SGP4SatData satData, PropInfo pInfo)
	Re-initialize an SGP4 propagator from RV info.
static int double3 double3 Orbital.COEStruct coe	RVforTime (ref SGP4SatData satData, double timeJD, double scaleLToKm, double scaleKmsecToV)

Static Public Attributes
const int	EARLY_PROPAGATION_ERROR = 2
static int	error
	Used in direct propagation mode, typically with an explicitly created SGP4 propagator that was created in test or user code (and not from within GE).
const int	OK = 0
static int double3	r
const int	SGP4_ERROR = 1
static int double3 double3	v

Detailed Description

Code to propagate SGP4 satellites i.e. satellites in Earth orbit with modeling for atmosphere, oblate gravity, moon, sun etc.

This code assumes the Earth is at the center of physics space.

Not hard to C&P the center body code from Kepler but seems like an uncommon use-case, so wait until someone asks....

Member Function Documentation

Evolve()

static bool GravityEngine2.SGP4Propagator.Evolve ( double tSec, ref NativeArray< PropInfo > propInfo, int i, ref GEBodyState state, double scaleLtoKm, double scaleKmsecToV, double startTimeJD )

static

Evolve an SGP4 propagator to a given time.

This entry point is used by StateForIdAtTime to evolve an SGP4 propagator to a given time.

Parameters

tSec
propInfo
i
state
scaleLtoKm
scaleKmsecToV
startTimeJD

Returns

EvolveAll()

static bool GravityEngine2.SGP4Propagator.EvolveAll ( double tSec, ref GEPhysicsCore::GEBodies bodies, ref NativeArray< PropInfo > propInfo, in NativeArray< GEPhysicsCore::PatchInfo > patchInfo, in NativeArray< int > indices, int lenIndices, double scaleLtoKm, double scaleKmsecToV, double startTimeJD )

static

GE entry point, to evolve a set of SGP4 bodies as defined by the indices index list.

Individual bodies may have different outcomes (decay, early propagation error) etc. This is indicated by setting the status field of the PropInfo struct and setting a return flag. The caller must then check all bodies.

Parameters

tSec	time in seconds
bodies
propInfo
patchInfo
indices
scaleLtoKm
scaleKmsecToV
startTimeJD

ManeuverPropagator()

static void GravityEngine2.SGP4Propagator.ManeuverPropagator ( int bodyIndex, double tSec, double timeJD, ref GEPhysicsCore::GEBodies bodies, ref NativeArray< PropInfo > sgp4Props, double scaleLtoKm, double scaleKmSecToV )

static

Change the state of an SGP4 propagator from a maneuver. Current r, v have been updated, so re-calculate the SGP4 state. Blend the result back to the current SGP4 state over a short period, typically 2% of the orbit period.

Parameters

bodyIndex
timeJD
bodies
sgp4Props
scaleLtoKm

ReInit()

static PropInfo GravityEngine2.SGP4Propagator.ReInit ( double tSec, double timeJD, double3 rKm, double3 vKm, Orbital::COE coeKm, ref SGP4SatData satData, PropInfo pInfo )

static

Re-initialize an SGP4 propagator from RV info.

Setup blending to the current SGP4 state over a short period, typically 5% of the orbit period.

PropInfo struct is copied by value, so return after updating.

Parameters

tSec
timeJD
rKm
vKm
coeKm
satData
pInfo

Member Data Documentation

error

int GravityEngine2.SGP4Propagator.error

static

Used in direct propagation mode, typically with an explicitly created SGP4 propagator that was created in test or user code (and not from within GE).

Evolution for time earlier than the epoch is allowed.

Parameters

satData
timeJD
scaleLToKm
scaleKmsecToV

Returns

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The documentation for this class was generated from the following file:

• ge2/GE2/Assets/GravityEngine2/Runtime/Core/Propagators/SGP4Propagator.cs