Building the SKA telescope will be a significant technological undertaking. The task will employ the skills of large numbers of engineers, scientists and technicians around the world. The SKA will be a complex system incorporating a range of different radio receiver types and communications equipment, several supercomputers and novel cooling and energy generation technologies.
Using a technique called ‘interferometry’, astronomers can link multiple radio telescope antennas together so that they act as one single, large telescope. This improves the resolution of the image they can generate and increases the collecting area of the telescope, making it more sensitive. The SKA will incorporate millions of linked antennas and supercomputers will be needed to process the signals they receive. The supercomputing facility built for the SKA will need to be about 3 times more powerful than the most powerful supercomputer in 2013.
The Australian SKA supercomputing facility will be housed in the Pawsey Supercomputer Centre in Perth, Western Australia.
A variety of radio receivers will be employed by the SKA telescope, each designed to perform certain tasks.
Traditional steerable ‘dish type’ antennas will be used in the mid frequency dish array. These dishes will receive radio waves from 500 MHz to 10 GHz. Each of the 130 dishes will be approximately 15 metres wide and about three storeys tall.
Image credit: SKA Organisation/Eye Candy.
Two types of non-moving (fixed) antennas will be used in the SKA. Unlike dishes which focus on a small part of the sky, these antennas will capture radio waves from the entire sky. Supercomputers process these signals and calculate the origin of radio signals. Fixed low frequency antennas will be used in the low frequency aperture array. These antennas will receive radio from 70 MHz to 450 MHz. Each of the up to 5 million antennas will be approximately 1.5 metres tall.
Fixed mid frequency antennas will be used in the mid frequency aperture array which is planned for SKA Phase two. These antennas will be football field-sized arrays comprised of internal antenna panels of wide, flat metallic sheets.
The data received by individual antennas will be converted to a digital signal, and then transmitted along optical fibre to a central correlator. At the central correlator, this data will be compressed and transmitted to the SKA supercomputing facility.
Energy generation and cooling
The SKA antennas and computers will consume large amounts of electricity, and its computers will produce heat that must be cooled. The SKA project is committed to minimising the cost and environmental impact of these energy demands.
The Murchison Radio-astronomy Observatory (MRO) is home to a specialised ground-coupled cooling system that will reduce the SKA’s need for electricity. The MRO also houses a hybrid solar-biodiesel power plant that provides power for ASKAP and MWA. The final power solution for the full SKA telescope is still being explored.
The Pawsey Supercomputer Centre in Perth employs experimental groundwater cooling to reduce water and electrical consumption.