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GLONASS: Reflector Information

RetroReflector Array (RRA) Characteristics:

Retro-reflector In-Space (RIS)
Drawing of corner cube, all units in mm. Courtesy of IPIE

Each GLONASS satellite is equipped with a laser retroreflector array built by the Institute for Precision Instrument Engineering (Russia). The retroreflector array is a 120 centimeter by 120 centimeter planar array with 396 fused-quartz corner cubes (center of mass relative to the RRA, arrangement of corner cubes). Such an RRA array is on each GLONASS satellite launched before 1996. A similar but much smaller designed Russian array is used on GPS-35, -36. There is no masking and no obstacles to the CCR arrays with respect to the laser beam incidence angle. The refractive index for various wavelengths is in the table below.

wavelength (microns) refractive index
0.350 1.4769
0.400 1.4701
0.532 1.4607
0.800 1.4532
1.064 1.4496
1.540 1.4438

Newer GLONASS satellites have different RRA than other GLONASS satellites:

  • GLONASS-84 has 132 corner cubes (132 cube arrangement). The corner cubes are mounted within a circular area having a 330-mm radius.
  • Two (GLONASS-86, -87) of the three GLONASS satellites launched on December 1, 2001 (GLONASS-86, -87, -88) have the same array as GLONASS-84, but one (GLONASS-88) has a different array of only 124 cubes (124 cube arrangement).
  • GLONASS-95, -99, and above up to -115 have 112 corner cubes (112 cube arrangement).
  • All corner cubes on the GLONASS satellites have a metal coat on their back faces, except for those satellites carrying uncoated retroreflectors.
  • GLONASS-115, -122, -123, and -124 all have uncoated retroreflectors. All future GLONASS M and K series spacecraft (launched after GLONASS-125) will also have the LRR arrays without coating.
  • GLONASS-125 is a new GLONASS-K satellite with a 123 corner cube arrangement; CoM values have been provided for the satellite. The LLR array on GLONASS-125 is the last satellite with an array with aluminum coating.

Additional information: