The square kilometre array baseline design V2.0

In April 2014 the SKA Organisation initiated a process to re-baseline the first phase of the SKA (SKA1) Construction Project. The objective of this process was the scoping and scaling of a system that delivers the maximum science throughput at a cost consistent with the original cost cap of € 650M. Based on costing information from the elements constituting the SKA telescopes (SKA1-Low / SKA1-Mid / SKA1-Survey), a scalable cost model was developed that allowed the analysis of science performance against cost for different options. Using this cost model a set of re-baselining options were developed, using an objective method based on the Monte Carlo technique, which would provide an optimum range of science impact. These sets of re-baselining options were reviewed by external science and engineering expert panels and finally presented to the SKA Board in early March 2015 for a final decision. On March 6^th, 2015 the SKA Board of Directors unanimously agreed to proceed with the design and construction of the € 650M SKA1 consisting of two complementary world-class instruments - one in Australia (SKA1-Low) and one in South Africa (SKA1-Mid) - both expecting to deliver exciting and transformational science.