Past activities at GGAO
Laser link experiments: During the early years at GGAO, the former Instrument Electro-Optics Branch performed pioneering experiments to study the effect of atmospheric turbulence on the propagation of coherent light. A laser link was established between a ground station and a detector of the GEOS-II satellite to monitor the effect of scintillation on the uplink in support of ongoing research in laser ranging and communication systems. The Skylab astronauts used a laser beam generated from GGAO to accurately determine their position and attitude in space and to calibrate on-board instruments.
PRARE: GGAO was also the home of a Precise Range And Range-Rate Equipment (PRARE) terminal. This terminal provided orbit determination data for several European satellites. It is located at GGAO as the result of a cooperative effort among NASA, the University of Texas, and the Technical University of Delft in the Netherlands. Unfortunately, the PRARE equipment at GGAO is no longer operational.
GTOTE: Historically, GGAO was the home of the Gamma Ray To Optical Transient Experiment (GTOTE) which was another rapidly moving system that obtained its target coordinate directly from the Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma Ray Observatory spacecraft.
Lunar laser ranging: From GGAO, the University of Maryland has successfully ranged, with a few centimeter accuracy, to retroreflectors placed on the moon by three manned Apollo missions and two unmanned Soviet Lunakhod missions; laser ranging to the Moon continues with a subset of stations in the ILRS network.
Time transfer experiments: The University of Maryland group has also transferred time with sub-nanosecond accuracies between atomic clocks at the GGAO and the U.S. Naval Observatory by bouncing laser pulses off a series of mirrors between the two sites, including one in the Washington Cathedral Tower. Using CO2 laser communication technology developed at GSFC, scientists used the technique of laser heterodyne spectrometry at the facility to obtain high resolution infrared spectra of several planetary atmospheres including Venus, Mars, and Jupiter.
