ElementConvert(Variable, Variable, TimeSpan, Array, Variable, Variable) Function

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Description

Converts the orbital state specified by elementArray from the fromSystem element set to the toSystem element set, specifying the value of B* to use when converting to or from the SGP4 element set by bStar and the central body gravitational parameter by mu. B* can only be specified when fromSystem or toSystem is SGP4. The order of the elements for each element set are listed below (using the Spacecraft properties):

- CARTESIAN: X, Y, Z, VX, VY, VZ

- KEPLERIAN: A, E, I, RAAN, W, TA

- NONSINGULAR_KEPLERIAN: NonSingularA, NonSingularE1, NonSingularE2, NonSingularE3, NonSingularE4, NonSingularE5

- EQUINOCTIAL: EquinoctialA, EquinoctialH, EquinoctialK, EquinoctialP, EquinoctialQ, EquinoctialLongitude

- BROUWER_MEAN: BL_A, BL_E, BL_I, BL_RAAN, BL_W, BL_MA

- J2_BROUWER_MEAN: BLJ2A, BLJ2E, BLJ2I, BLJ2RAAN, BLJ2W, BLJ2MA

- SPHERICAL: SphericalRadius, RA, DEC, Vi, SphericalAzimuth, VerticalFPA

- SPHERICAL_LATLONG: LatLongRadius, Latitude, Longitude, LatLongVi, LatLongAzimuth, HorizontalFPA

- SGP4: Mean I, Mean RAAN, Mean E, Mean W, Mean MA, Mean MeanMotion

- MODIFIED_EQUINOCTIAL: ModifiedEquinoctialP, ModifiedEquinoctialF, ModifiedEquinoctialG, ModifiedEquinoctialH, ModifiedEquinoctialK, ModifiedEquinoctialL

- SGP4 EQUINOCTIAL: Mean EquinoctialH, Mean EquinoctialK, Mean EquinoctialP, Mean EquinoctialQ, Mean EquinoctialLongitude, Mean EquinoctialMeanMotion

Note, when used to convert an element set into SGP4 elements this function is not compatible with the SGP4/SDP4 propagator.

Timing Precision Mode

This page describes functionality in nanosecond timing precision mode.

Function Signature

ElementConvert(	Variable fromSystem,
	Variable toSystem,
	TimeSpan epoch,
	Array elementArray,
	Variable mu,
	Variable bStar)

Arguments

fromSystem

Description:

Element set of input state.

Valid Values:

Value	Label
1	CARTESIAN
2	KEPLERIAN
3	NONSINGULAR_KEPLERIAN
4	EQUINOCTIAL
5	BROUWER_MEAN
6	J2_BROUWER_MEAN
7	SPHERICAL
8	SPHERICAL_LATLONG
9	SGP4
10	MODIFIED_EQUINOCTIAL
11	SGP4 EQUINOCTIAL

toSystem

Description:

Element set of output state.

Valid Values:

Value	Label
1	CARTESIAN
2	KEPLERIAN
3	NONSINGULAR_KEPLERIAN
4	EQUINOCTIAL
5	BROUWER_MEAN
6	J2_BROUWER_MEAN
7	SPHERICAL
8	SPHERICAL_LATLONG
9	SGP4
10	MODIFIED_EQUINOCTIAL
11	SGP4 EQUINOCTIAL

epoch
Description:	The TAI epoch of the orbital state in modified Julian date format.

elementArray

Description:

A six-element array containing the orbital state in the input element set.

When converting TO Spherical Lat-Long. or SGP4, the input state is assumed to be referenced to the ICRF. When converting FROM Spherical Lat-Long., the input state is assumed to be in the Earth Fixed coordinate system. When converting FROM SGP4, the input state is assumed to be in the TEME coordinate system.

For all other conversions, the output state will be referenced to the same coordinate system as the input state.

Required Size:

At least 6

mu
Description:	Specifies the value of Mu (gravitational parameter of central body) to use in the element conversion.
Units:	km3/s2
Valid Range:	mu > 0

bStar
Description:	Specifies the value of BStar to use when converting to or from the SGP4 element set.

Return Value

Type:

Array of number (size = 6)

Returns a six-element array containing the orbital state in the output element set. When converting TO SGP4, the output state will be referenced to the TEME coordinate system. When converting FROM SGP4, the output state will be referenced to the ICRF.

Syntax

myArray1 = ElementConvert(myVariable1, myVariable2, myTimeSpan1, myArray2, myVariable3, myVariable4);