An Introduction to Subcentimeter Satellite Laser Ranging: Hardware and Applications

Satellite laser ranging (SLR) to an artificial satellite equipped with a passive retroreflector array was first demonstrated by the NASA Goddard Space Flight Center in 1964. Over the past three decades, the range precision has improved by roughly three orders of magnitude - from a few meters to a few millimeters - and over 50 satellites have been tracked by laser. Today, an international network of over 40 stations routinely track a constellation of over 20 artificial satellites and the Moon in support of a wide range of applications. Science applications include a a geocentric global reference frame accurate to a centimeter, the monitoring of tectonic plate motion, regional crustal deformation near plate boundaries, the static and time varying components of the Earth’s gravity field, motion of the Earth’s spin axis, variations in the Earth rotation rate (Length of Day), surface topography (oceans, land, and ice), monitoring of large mass movements within the atmosphere and oceans and providing constraints to global circulation models, lunar physics, general relativity, and the measurement of fundamental physical constants. Engineering applications include precise orbit prediction, the measurement of nonconservative forces in space, subnanosecond global time transfer between atomic clocks and the calibration and testing of groundbased microwave radars as well as new spacebased navigation systems such as the Global Positioning System (GPS).