The Square Kilometre Array

The Square Kilometre Array (SKA) Project is a global project to design and c- struct a revolutionary new radio telescope with of order 1 million square meters of collecting area in the wavelength range from3mto1cm.It will have two - ders of magnitude greater sensitivity than current telescopes and an unprecedented large instantaneous ?eld-of-view. These capabilities will ensure the SKA will play a leading role in solving the major astrophysical and cosmological questions of the day (see the science case at www.skatelescope.org/pages/page astronom.htm). The SKA will complement major ground- and space-based astronomical facilities under construction or planned in other parts of the electromagnetic spectrum (e.g. ALMA, JWST, ELT, XEUS,...). The current schedule for the SKA foresees a decision on the SKA site in 2006, a decisiononthedesignconceptin2009,constructionofthe?rstphase(international path?nder)from2010to2013,andconstructionofthefullarrayfrom2014to2020. The cost is estimated to be about 1000 M . TheSKAProjectcurrentlyinvolves45institutesin17countries,manyofwhich are involved in nationally- or regionally-funded state-of-the-art technical devel- ments being pursued ahead of the 2009 selection of design concept. This Special Issue of Experimental Astronomy provides a snapshot of SKA engineering act- ity around the world, and is based on presentations made at the SKA meeting in Penticton,BC,CanadainJuly2004.Topicscoveredincludeantennaconcepts,so- ware, signal transport and processing, radio frequency interference mitigation, and reports on related technologies in other radio telescopes now under construction. Further information on the project can be found at www.skatelescope.org.