Smithsonian Astrophysical Observatory laser tracking systems

The Smithsonian Astrophysical Observatory operates four laser satellite-ranging systems in support of geodetic and geophysical research. The lasers-located in Brazil, Peru, Australia, and Arizona-have been in operation for more than 5 years and have provided ranging data at accuracy levels of a metre or better. To meet new requirements in geophysics, these systems are now being upgraded to improve range accuracy and performance. The lasers are being equipped with electronic pulse processors, to analyse returnpulse wave shape, and pulse choppers, to reduce laser pulse width. Initial results indicate that the upgraded ranging system hardware will meet the decimetre ranging-accuracy requirements for the Geos 3 and Seasat satellites and for Earth-dynamics projects based on satellites such as Starlette.