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SLR Center-of-Mass (CoM) Measurement Correction Information

The following table shows the components of the satellite body-fixed offset of the SLR array phase center (LRA offset: the blue vector in this SLR center of mass correction Concept Diagram) in the satellite's coordinate system. The total SLR center of mass correction (red vector) should be computed by using the LRA offset vector and the satellite Center of Mass (CoM) offset vector (green vector). The CoM offset may vary slightly with time, depending upon the use of propellant for satellite momentum dumps, satellite orbit maneuvers, antenna orientation changes, et cetera. The "location" of the LRA phase center may also vary; it is the locus of points from which the return came as a result of a particular satellite-station geometry and station characteristics (single or multiple photon, receiver type, et cetera).

 Satellite Size of Array Number of Reflectors Body Fixed Coordinates
of Array Phase
Center (mm)		 Spacecraft Coordinate
Definition 		CoM Correction (mm)
and details
 ADEOS-1 35.6 cm edge hollow cube 1 ? ?
 ADEOS-2 16 cm diameter hemisphere 9 (+5000, +1050, +500) Y-axis anti-parallel with velocity,
Z-axis away from nadir
 Ajisai 214 cm diameter sphere 1,436 1028 sphere: radius of
phase center of each cube		 details
 Beacon-C Pyramidal array on
nadir face		 160 ? phase center of each cube
 BLITS 85.16 mm diameter sphere 1 (0, 0, 0) origin at center of the single sphere details
 CHAMP 5cm diameter,
45 deg pyramid		 4 (0, 0, 250) Z-axis towards nadir details
 CryoSat-2 11.4 cm diameter, 0 or 57.5 deg pyramid 7 (1808.5, -935.0, -450.0) plus 15-25 mm for LRA
details		 X-axis 6° from the flight direction (nose-down), negative-Z-axis 6°
from the nadir, Yaw steering (normal operation) applied so that
Y-axis orthogonal to the satellite ground track		 details
 Envisat 20 cm diameter hemisphere 9 (-1058, +1359, -1183) X-axis direction of satellite pitch,
Z-axis away from nadir		 details
 ERS-2 20 cm diameter hemisphere 9 (1000, -710, -1010) X-axis direction of satellite pitch,
Z-axis away from nadir
 Etalon-1, -2 129.4 cm diameter sphere 2,134 614 sphere: radius of
phase center of each cube		 details
 Galileo-101 33 mm diameter, 23.3 mm height 84 (1092, -34, 621) X-axis negative to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir		 details
 Galileo-102 33 mm diameter, 23.3 mm height 84 (1093, -34, 623) X-axis negative to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir 		details
 GFO-1 16 cm diameter hemisphere 9 (+182, +753, +599) Y-axis anti-parallel with velocity,
Z-axis away from nadir		 details
 GFZ-1 20 cm diameter sphere 60 sphere: radius of
phase center of each cube		 58 +/- 2
 GIOVE-A 30x40 cm planar array 76 (-828, -655, +688) X-axis negative to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir,
attitude details		 details
 GIOVE-B 30x30 cm planar array 67 (-804.3, +294.1, +1330.1) X-axis negative to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir,
attitude details		 details
 GLONASS 120x120 cm planar array 396 (-1542, 0, 0) X-axis away from nadir,
Y-axis negative to hemisphere containing the Sun,
Z-axis along solar panel
 GLONASS 66x66 cm planar array 132 (-1555, 0, 0) X-axis away from nadir,
Y-axis negative to hemisphere containing the Sun,
Z-axis along solar panel
 GLONASS 66x66 cm planar array 124 (-1522, 0, 0) X-axis away from nadir,
Y-axis negative to hemisphere containing the Sun,
Z-axis along solar panel
 GLONASS-95, -99, -100, -102, -109, -115 30x50 cm planar array 112 (-1874, -137, +3) X-axis away from nadir,
Y-axis negative to hemisphere containing the Sun,
Z-axis along solar panel 		details
 GLONASS-125 annulus array 123     details
 GPS-35 23.9x19.4 cm planar array 32 (862.6, -524.5, 669.5)

X-axis positive to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir

 details
 GPS-36 23.9x19.4 cm planar array 32 (862.6, -524.5, 671.7) X-axis positive to hemisphere containing the Sun,
Y-axis along solar panel,
Z-axis towards nadir		 details
 GRACE-A, -B 10 cm diameter,
45 deg pyramid		 4 (-600, -327.5, 217.8) X-axis is the 'front', Z-axis towards nadir, Y-axis completes the orthogonal system details
 Gravity Probe B Open hemisphere 9 (0, 0, -1820) +Z-axis towards RA 343.26deg, DEC 16.84deg details
 ICESat 16 cm diameter hemisphere 9 (-1045, -4, 280)
(plus 4.5 cm for the LRA)		 X-axis towards
satellite zenith,
Y-axis along solar panel		 details
 Jason-1 hemisphere 9 (1171, 598, 6828) (-49 mm for the LRA) X-axis in direction of
velocity,
Z-axis towards nadir		 details
 Jason-2 hemisphere 9 (1194, 598, 6838) (-49 mm for the LRA) X-axis in direction of
velocity,
Z-axis towards nadir		 details
 LAGEOS-1 60 cm diameter sphere 426 258 sphere: radius of
phase center of each cube		 details
 LAGEOS-2 60 cm diameter sphere 426 258 sphere: radius of
phase center of each cube		 details
 LARES 36.4 cm diameter sphere 92 137.1 sphere: radius of phase center of each cube details
 Larets 20 cm diameter sphere 60 56.2 sphere: radius of
phase center of each cube		 details
 LRE quasi-spherical,
47x51 cm diameter		 126 sphere: radius of
phase center of each cube		 210
 Meteor-3M spherical ball,
6 cm diameter		 1 (+113, +475.7, +2101.5) ? details
 SARAL hemisphere 9 (4735, 0, -940) (-43.4mm for the LRA X-axis is nadir pointing, Z-axis opposite to cross track
 Starlette 24 cm diameter sphere 60 sphere: radius of
phase center of each cube		 75
details
 Stella 24 cm diameter sphere 60 sphere: radius of
phase center of each cube		 75
 TOPEX/Poseidon 150 cm diameter annulus 192 (+1079, +418, +827) Center of annulus.
X-axis in
direction of velocity,
Z-axis towards nadir		 details
 WESTPAC 24 cm diameter sphere 60 63.4 Radius of satellite through front face of the cubes (91mm) details