Construction of the world’s largest radio astronomy facility, the SKA Observatory, begins today. The observatory is a global project 30 years in the making. With two huge telescopes, one in Australia and the other in South Africa, the project will see further into the history of the universe than ever before. Astronomers like me will use the telescopes to trace hydrogen over cosmic time and make precise measurements of gravity in extreme environments. In addition, we hope to reveal the existence of complex molecules in planet-forming clouds around distant stars, which could be the first signs of life elsewhere in the universe. I have been involved with the SKA and its precursor telescopes for the past ten years and as chief operations scientist of the Australian telescope since July. I’m helping build the team of scientists, engineers and technicians who will build and operate the telescope, along with the science to map primordial hydrogen in the infant universe. What is the SKA Observatory? The SKA Observatory is an intergovernmental organization with dozens of participating countries. The observatory is much more than just two physical telescopes, based in the UK and partners around the world who use advanced computers and software to tailor the telescope’s signals to the precise science being undertaken. The telescope in South Africa (called SKA-Mid) will use 197 radio dishes to observe medium-frequency radio waves from 350 MHz to more than 15 GHz. It will study the extreme environments of neutron stars, the organic molecules around newly formed planets, and the structure of the universe on the largest scale. The Australian Telescope (SKA-Low), in Western Australia, will observe lower frequencies with 512 radio antenna stations spread over 74 kilometers outside the region. The site is at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio Observatory. This name, meaning “sharing sky and stars”, was given to the observatory by the Wajarri Yamaji, the traditional owners and native title holders of the observatory site. Tuning in the universe After decades of planning, development of precursor telescopes and testing, today we are holding a ceremony to mark the start of on-site construction. We expect both telescopes to be fully operational by the end of this decade. Each of SKA-Low’s 512 stations consists of 256 wideband dipole antennas, spread over a 35-meter diameter. The signals from these Christmas tree-shaped antennas at each station are combined electronically to point at different parts of the sky, forming a single view. These antennas are designed to tune in low radio frequencies of 50 to 350 MHz. At these frequencies, the radio waves are very tall—comparable to the height of a person—which means that more intimate-looking dishes are an inefficient way to catch them. In contrast, dipole antennas work like television antennas, with radio waves from the universe exciting electrons inside their metal arms. Collectively, the 131,072 dipoles in the complete array will provide the deepest and widest view of the universe to date. Staring at the cosmic dawn They will allow us to see out and back to the beginning of the universe, when the first stars and galaxies formed. This key period, more than 13 billion years in our past, is called the “cosmic dawn”: when stars and galaxies began to form, lighting up the universe for the first time. Cosmic dawn marks the end of the cosmic dark ages, a period after the Big Bang when the universe had cooled due to expansion. All that remained was the ubiquitous background glow of the universe’s early light and a world filled with dark matter and neutral hydrogen and helium atoms. Light from the first stars transformed the universe, splitting electrons and protons into neutral hydrogen atoms. The universe went from dark and neutral to bright and ionized. The SKA Observatory will map this nebula of neutral hydrogen at low radio frequencies, which will allow scientists to explore the births and deaths of the first stars and galaxies. Exploring this key period is the last missing piece in understanding the life history of the universe. Unfathomable mysteries Closer to home, the low-frequency telescope will time the turns of pulsars. These rapidly spinning neutron stars, which emit sweeping beams of radiation like beacons, are the universe’s extremely precise clocks. Changes in the ticking of these clocks may indicate the passage of gravitational waves through the universe, allowing us to map these distortions of spacetime with radio waves. It will also help us understand the Sun, our own star and the space environment in which we live on Earth. These are the things we expect to find with the SKA Observatory. But the unexpected discoveries will likely be the most exciting. With an observatory of this size and power, we are bound to uncover mysteries of the universe that have yet to be imagined. Powered by The Conversation
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