Mills Cross Telescope, Radio telescope in Badgerys Creek, Australia

Mills Cross Telescope is a radio telescope in Badgerys Creek composed of two perpendicular antenna arrays, each extending 450 meters in north-south and east-west directions. The structure used a straightforward arrangement of dipole antenna elements to capture radio waves from space.

The facility operated from 1954 to 1991 at the Fleurs field station, conducting systematic sky surveys through its antenna configuration. Researchers identified over 2,000 discrete radio emission sources during this productive period.

The cross gave its name to a whole telescope class, the Mills cross, later copied in the United States, Italy, Russia and Ukraine. Its beam was steered by adjusting the phasing of the dipole elements in each arm. The 2,300-source MSH Catalogue, named after Mills, Slee and Hill, appeared until 1961.

Operating at 85.5 MHz enabled a resolution of roughly 49 arcminutes, allowing precise measurements of radio signals from space objects. Visitors should know the facility no longer operates actively, though the historical antenna structures remain visible on site.

The cross design with two perpendicular antenna rows created an observation ability equivalent to a single enormous antenna without needing its physical scale. This clever approach showed how effective instruments could be built through smart geometric arrangement instead of massive construction.