Radio science and radio tracking instrumentation at the NASA Deep Space Network (DSN) 
            utilize capabilities of the DSN in combination with telecommunications equipment
            on board spacecraft to make measurements that can be used to study gravity fields, 
            relativistic effects, and the properties of plasmas, and planetary surfaces, atmospheres, 
            ionospheres, and rings throughout the solar system.  The DSN also sends commands to
            spacecraft and receives telemetry from them.  This equipment may also be used for
            reception only, such as for radio astronomy observations of natural sources and 
            for very long baseline interferometry.  With few exceptions, this instrumentation
            is available for connection to any DSN antenna. Performance then depends on antenna size,
            wavelength, transmitter and low-noise amplifier selected, and local observing conditions.
            The instrumentation has evolved over time since the DSN was established in the 1960s.