From the Byrd telescope in West Virginia, to the Arecibo Telescope in Puerto Rico, to the MeerKAT system in South Africa, the world is not hurting for gigantic radio telescopes. These large arrays are precise and powerful, but come 2024, they will all be eclipsed by the capability of the Square Kilometre Array—a telescope system big enough to answer science's deepest questions about the nature of our universe.
When it comes to radio telescopy, systems come in two varieties—humongous single dishes like 305-meter-wide Aricebo or as a collective of smaller individual dishes coordinating, like the MEERKAT array. Arrays boast a distinctive advantage over the dishes—the smaller individual dishes can be spread over a vastly larger area than a single dish could ever cover, granting the array a much greater collection area. Bigger collection areas translate into a larger searchable field of view and more data to study. The MeerKAT, current record holder for largest and most precise array telescope, has a collection area of about 18,000 square meters. When the $1.9 billion SKA is completed, it will provide, as its name suggests, a million square meters of collection area. It will be fifty times more precise than any other radio system on the planet, and it will be able to survey the sky ten thousand times faster than current systems. Ten thousand.
The SKA project has been in development since 1991 and is comprised of 20 nations. The system will be broken into two halves—one site in rural South Africa (as well as remote sites in Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia). The other half will be in Australia's and New Zealand's most remote regions. These locations were chosen because the Southern Hemisphere has a better view of the Milky Way, and it provides the least amounts of man-made radio interference.
The array itself will be populated by about 3,000 individual 15-meter tall, 12-meter wide receivers that, with help from its sister arrays, will span the 70 MHz to 10 GHz spectrum. The SKA will feature a core group of receivers at each site as well as 2,000 mile-long tendrils extending out from the center (which is why the S. African group also has partners in eight other African nations). These arms will be tied together by high-speed fiber optic lines which will dump roughly 937,500 terabytes of data into a central-processing super computer every day—that's 100 times today's global internet traffic. In addition, the system will also employ a mid-frequency aperture array consisting of 250 separate stations, each of which uses 160,000 receivers, and a low-frequency aperture array boasting 2.5 million receivers used to detect neutral hydrogen, a building block of the early universe. In all, this will provide the highest resolution images in all of astronomy.
The array is being constructed in three phases, which is ingenious because it will allow the telescope to begin working before it's fully operational. The first phase will involve repurposing the existing 64-dish MeerKAT system while building 190 more in 2016. "The decision recognises MeerKAT as a key instrument that will make up one quarter of SKA Phase 1 mid-frequency array, and the science planned for SKA Phase 1 is very similar to the MeerKAT science case—just much more ambitious," Professor Justin Jonas, Associate Director: Science and Engineering at SKA South Africa, explained in a press release. "Our researchers and students who participate in the MeerKAT surveys have a huge advantage. They are well placed to enter SKA Phase 1. They have the opportunity to become science leaders in future SKA projects."
That leadership comes at a price, mind you. By the project's completion, the low frequency arrays alone will number in the millions. So, in order to keep costs from skyrocketing, engineers at Cambridge University, who had already designed a low frequency receiver for the SKA project, turned to Cambridge Consultants, a cutting-edge technology design and development firm, for assistance.
The team from Cambridge Consultants was tasked with modifying the existing prototype design to make it cheaper and easier to produce, less expensive to ship, and easier to assemble in the field—all while maintaining the receiver's structural integrity and environmental resistance.
"The challenge of volume manufacture is at the forefront of our work with the SKA program," Gary Kemp, Program Director at Cambridge Consultants, said in a press release. "The two-meter-tall antennas will have to be manufactured in very high volumes – more than 2.5 million will be required, in addition to the 40 million antennas of the mid-frequency array. So ‘commercializing' the design through the design for manufacture process is critical to the feasibility of the SKA. To see a mature design for part of the physical hardware that will make up the core of the world's biggest telescope is an important step towards the construction of the final instrument."
"The design is kind of like TV aerials," Richard Williams of Cambridge Consultants told Gizmodo. "Essentially, whatever design you're going to do is going to involve bent metal. The University had already come up with a concept design for the geometric shape of the antenna, one that gave them good which had a beautiful directionality. They had a shape that they were happy with but they hadn't thought at all how to make it cheaply and in quantity. We quickly looked at this and—in an array antenna, all the signal goes around the edge of any metal, so we moved from using sheet metal to rod and wire and quickly onto wire bent-metal. That reduced a lot of the cost of the design."
To further reduce costs, the team used injection molded plastics as an inexpensive means of insulating the antenna support structure. As for the control electronics, Cambridge Consultants turned to the mobile phone industry and employed mainly off-the-shelf PCB components normally used for front-end amplifiers. In all, the Cambridge Consultants team believes that they can effectively mass produce, ship, and install these arrays for just €70 or roughly $100 American per unit.