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Laser Tracking Reflector

NSSDC ID: 1976-039A-01
Mission Name: LAGEOS
Principal Investigator: Mr. Chris C. Stephanides


Laser retroreflectors covering a very dense spherical satellite were used to provide a permanent reference point in a very stable orbit for precision earth-dynamics measurements. This sphere was machined largely from depleted uranium, weighed about 411 kg, and was composed of a cubical inner core with six attached spherical caps. Each of the spherical caps had machined cavities to accommodate the retroreflectors. The satellite was placed at a high orbital inclination at an altitude of about 5000 km and tracked by a network of 13 laser stations operated by both U.S. and foreign agencies. The performance in orbit is limited only by degradation of the retroreflectors, and a minimum lifetime of 50 years is expected.

Facts in Brief

Mass: 411.0 kg


  • Earth Science: Geophysics/Geodesy

Additional Information

Questions or comments about this experiment can be directed to: Coordinated Request and User Support Office.



NameRoleOriginal AffiliationE-mail
Mr. Chris C. StephanidesPrincipal InvestigatorNASA Goddard Space Flight Center 
Dr. Henry H. PlotkinOther InvestigatorNASA Goddard Space Flight Center 
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