Card 6t - ORBDEF7 Spacecraft Rotation Parameters

This optional card defines the spacecraft rotation parameters.

Parameter Value Description
ORBDEF7 ORBDEF7 (or 47) Mnemonic
ID integer ID number
ROTVX real X component of the rotation vector in S/C coordinate system
ROTVY real Y component of the rotation vector in S/C coordinate system
ROTVZ real Z component of the rotation vector in S/C coordinate system
ROTRATE real Rotation of the S/C per orbit
STARRA real Star right ascension angle
STARDECL real Star declination
ROTFLAG 0 Constant rate
Integer Table number specifying variable rate S/C angular rotation

ROTVX

ROTVX is the X component of the spacecraft rotation vector in the global coordinate system. Otherwise, it should be 0.

ROTVY

ROTVY is the Y component of the spacecraft rotation vector in the global coordinate system. Otherwise, it should be 0.

ROTVZ

ROTVZ is the Z component of the spacecraft rotation vector in the global coordinate system. Otherwise, it should be 0.

ROTRATE

ROTRATE is the rotation in degrees per complete orbit of the spacecraft about the specified axis of rotation. If there is no rotation, it should be 0.

STARRA

STARRA is the star right ascension angle value in degrees if ORBDEF1 V1OPT = STAR or V2OPT = STAR. Otherwise, it should be 0.

The star right ascension angle is the angle measured eastward from the vernal equinox axis in the planet’s equatorial plane to the projection of the star vector onto the equatorial plane.

The vernal equinox is the time when the apparent position of the sun crosses the equator moving from south to north. The vernal equinox axis is a line from the Earth's center to the point where the sun crosses the equator moving from south to north.

STARDECL

STARDECL is the star declination in degrees if ORBDEF1 V1OPT = STAR or V2OPT = STAR. If not applicable, it should be 0.

The star declination angle is an angle in degrees measured from the planet’s equatorial plane to the star vector. It is positive northward and negative southward and is between -90 and +90 inclusively.

The star vector points to the star.

ROTFLAG

ROTFLAG is the table number if the rotation rate is defined via a rotation vs time table.

The table should be defined with a ROTAT vs TIME TABTYPE Card. If no table is specified, ROTFLAG should be 0.