Winkfield is one of the stations in the Space Tracking and Data Acquisition Network (Stadan) of the U.S. National Aeronautics and Space Administration (N.A.S.A.) and is operated by the Radio and Space Research Station as a joint venture with N.A.S.A. The stations in the network, using standardized equipment supplied by N.A.S.A., receive by radio telemetry measurements from the various experiments in the satellites, they command the functioning of satellites and they track them. Tracking, with which this paper is concerned, means the measurement of quantities which contribute to the determination of the positions of satellites as a function of time. About ten stations in the network use tracking equipment and methods identical with those used at Winkfield. The network operates 24 h a day, its functioning being coordinated by the Goddard Space Flight Center of N.A.S.A. by means of teleprinter circuits which also serve to convey the raw tracking information from the stations to the N.A.S.A. computer facilities.
Determination of mass and bulk density of asteroid (21) Lutetia using Rosetta radio tracking data
