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.