Featured image: A computer generated image of the Square Kilometre Array (SKA) radio telescope dish antennas in South Africa. Credit: SKA Project Office.
What is dark matter? What did the universe look like when the first galaxies formed? Is there other life out there? These are just some of the mysteries that the Square Kilometre Array (SKA) will aim to solve.
Covering an area equivalent to around one million square metres, or one square kilometre, SKA will comprise of hundreds of thousands of radio antennas in the Karoo desert, South Africa and the Murchison region, Western Australia.
The multi-billion dollar array will be 10 times more sensitive and significantly faster at surveying galaxies than any current radio telescope.
The massive flow of data from the telescope will be processed by supercomputing facilities that have one trillion times the computing power of those that landed men on the Moon.
Phase 1 of SKA’s construction will commence in 2018. The construction will be a collaboration of 500 engineers from 20 different countries around the world.
When operational in 2024, the SKA will generate data rates in excess of the entire world’s internet traffic.
ICRAR used an international consortium of astronomers to conduct a survey with the Janksy-VLA telescope, employing AWS to process the data, and they are now trying to determine how the services will work with a larger system.
“Things are changing quickly – if you do something today, it might be different next week.”
Quinn says cloud systems assist international collaboration by providing all researchers with access to the same data and software. They’re also cost-effective, offering on-demand computing resources where researchers pay for what they use.
In any given week, Tingay might be discussing a galaxy census, monitoring solar flares for the US Air Force or investigating the beginning of the universe.
Tingay is the Director of the Curtin Institute of Radio Astronomy at Curtin University, Deputy Director of the International Centre for Radio Astronomy Research and Director of the Murchison Widefield Array (MWA). Still less than two years old, the MWA has already entered uncharted territory, collecting data that will uncover the birth of stars and galaxies in the very early universe and produce an unprecedented galaxy catalogue of half a million objects in the sky. The MWA could also one day provide early warning of destructive solar flares that can knock out the satellite communications we rely on.
“To date, we’ve collected upwards of four petabytes of data and all the science results are starting to roll out in earnest now,” he says.
“It’s an amazing feeling for the team to have pulled together, delivered the instrument, and to do things that no one ever expected we could do when we did the planning.”
The project sees Curtin University lead a prestigious group of partners, including Harvard University and MIT, in four countries. And while the MWA is a powerful telescope in its own right, it paves the way for what is arguably the biggest science project on the planet – the Square Kilometre Array (SKA).
The promise of this multi-billion dollar telescope, which will be built across Western Australia and South Africa, drove Tingay to move to Perth seven years ago. “I like to be close to the action, building and operating telescopes, and using them to do interesting experiments that no one else has done before – in close physical proximity.”
His team of 55 researchers at Curtin University are working on the astrophysics, engineering and ICT challenges of the SKA.
“Curtin is an amazing place to work,” he says. “It’s focused on a few very high-impact developments and making sure that they’re properly funded and resourced.
“Periodically, I sit down and think: ‘Where else in the world would I rather be?’ and every time I conclude that for radio astronomy Curtin University in Perth is the best place to be.”
Today NASA announced the paradigm shifting discovery of flowing water on Mars. This extraterrestrial salty water bodes well for a water cycle on Mars, and potential hosting of Martian life. What mysteries lie on Mars, we may find out soon – but for the infinite mysteries that lie beyond – we have the Earth’s largest radio telescope, the Square Kilometre Array (SKA), manned by the Curtin Institute of Radio Astronomy.
The engineering challenges behind building the world’s biggest radio telescope are vast, but bring rewards beyond a better understanding of the universe.
Since its inception, the Curtin Institute of Radio Astronomy has established itself as an essential hub for astronomy research in Australia. Known as CIRA, the organisation brings together engineering and science expertise in one of Australia’s core research strengths: radio astronomy.
CIRA’s Co-Directors, Professors Steven Tingay and Peter Hall, were on the team who pitched Australia’s successful bid to host part of the SKA – a radio telescope that will stretch across Australia and Africa. The SKA’s two hosting nations were announced in May 2012 and the project forms the main focus of research at CIRA. And for good reason: the SKA-low – a low-frequency aperture array consisting of a quarter of a million individual antennas in its first phase – will be built in Western Australia at the Murchison Radio-astronomy Observatory (MRO), about 800 km north of Perth.
The near-flat terrain and lack of radio noise from electronics and broadcast media in this remote region allow for great sky access and ease of construction. At Phase 1, SKA-low will cover the project’s lowest-frequency band, from 50 MHz up to 350 MHz – with antennas covering approximately 2 km at the core, stretching out to 50 km along three spiral arms.
“Out of 10 organisations in a similar number of countries, CIRA is the largest single contributor to the low frequency array consortium,” says Hall, the Director responsible for engineering at CIRA.
Far from a traditional white dish radio telescope, which mechanically focuses beams, the SKA-low will be a huge array of electronic antennas with no moving parts. Its programmable signal processors will be able to focus on multiple fields of view and perform several different processes simultaneously. “You can point at as many directions as you want with full sensitivity – that’s the beauty of the electronic approach,” says Senior Research Fellow Dr Randall Wayth, an astronomer and signal processing specialist at CIRA.
One of the major scientific goals of SKA-low is to help illuminate the events of the early universe, particularly the stage of its formation known as the ‘epoch of reionisation’. Around 13 billion years ago, all matter in the early universe was ionised by radiation emitted from the earliest stars. The record of this reionisation carries with it telltale radio signatures that reveal how those early stars formed and turned into galaxies. Observing this directly for the first time will allow astronomers to unlock fundamental new physics.
“To see what’s going on there at the limits of where we can see in time and space, you have to have telescopes that are sensitive to wide-field, diffuse structures, and that are exquisitely calibrated. You have to be able to reject the foreground universe and local radio frequency interference,” says Hall. This sensitivity to diffuse structures will make SKA-low and its precursor, the Murchison Widefield Array (MWA), essential instruments in studying the epoch of reionisation.
The SKA-low will also be important in studying time domain astronomy, which consists of phenomena occurring over a vast range of timescales. One example is the field of pulsar study. Pulsars are incredibly dense rotating stars that, much like a lantern in a lighthouse, emit a beam of radiation at extremely regular intervals. This regularity makes pulsars useful tools for a variety of scientific applications, including accurate timekeeping.
By the time the radio signal from a distant pulsar travels across space and reaches Earth, it is dispersed. But with the right telescope, you can calibrate against this dispersion, and trace back the original regular signal.
“One of the great things you can do with a low frequency telescope such as the SKA-low is get a very good look at the pulsar signal,” says Hall. “As well as stand-alone SKA-low pulsar studies, the measurement of hour-to-hour dispersion changes can be fed to telescopes at higher frequencies, vastly improving their ability to do precision pulsar timing.”
“It’s a big advantage having the critical mass of people in this building to make things happen.”
It’s not just astronomy research that is benefiting from the construction of the SKA-low and its precursors (two precursor telescopes are in place at the MRO: the MWA and the Australian Square Kilometre Array Precursor telescope, ASKAP). In order to make the most out of the aperture array telescopes, some fundamental engineering challenges need to be solved. Challenges such as how to characterise the antennas to ensure that they meet design specifications, or how to design a photovoltaic system to power the SKA without producing too many unwanted emissions. Solving these problems requires both a deep understanding of the fundamental physics involved as well as knowledge of how to engineer solutions around those physics.
The projected construction timeframe for SKA-low is 2018–2023, but there is already infrastructure in place to begin testing its design and operation. Consisting of 2048 fixed dual-polarisation dipole antennas arranged in 128 ‘tiles’, the MWA boasts a wide field of view of several hundred square degrees at a resolution of arcminutes. It has provided insight into the challenges that will arise during the full deployment of SKA-low, not the least of which is managing the volume of data resulting from the measurements.
“The MWA already has a formidable data rate. We transmit 400 megabits per second down to Perth, and processing that is a substantial challenge,” says Wayth. The challenge is a necessary one, as the stream of data that comes from a fully operational SKA-low will be orders of magnitude larger.
“While doing groundbreaking science, the MWA is just manageable for us at the moment in terms of data rate. It teaches us what we have to do to handle the data.”
Continued CIRA developments at the MRO have included the construction of an independently commissioned prototype system, the Aperture Array Verification System 0.5 (AAVS0.5). The results from testing it in conjunction with the MWA surprised the engineers and scientists. “Engineers know that building even a tiny prototype teaches you a lot,” says Hall.
In their case, some carefully-matched cables turned out to be mismatched in their electrical delay lengths. Using the AAVS0.5, they have already been able to improve the MWA calibration. “We were able to feedback that engineering science into the MWA astronomy calibration model, and we now have a better model to calibrate and clean the images from the MWA,” says Hall.
Following the success of AAVS0.5, over the next two years CIRA will be leading the construction of the much larger AAVS1, designed to mimic a full SKA-low station.
Developing the SKA-low and its precursors is an huge effort, demanding the best in astrophysics, engineering and data processing. CIRA is uniquely positioned to accomplish this feat, with a large research staff, fully equipped engineering laboratory and access to the nearby Pawsey Supercomputing Centre for data processing. “CIRA has astronomers and engineers, as well as people who do both. We have all the skills to do these things in-house,” says Hall.
“It’s a big advantage having the critical mass of people in this building to make things happen,” says Wayth. “It’s a rare case where the sum of the parts really is greater than the whole.”
Opportunities for students and early-career researchers to engage in the project are already underway. Dozens of postgraduate research projects commencing in 2015 will involve the MWA, AAVS and ASKAP directly. Topics range from detecting the radio signature of fireballs to investigating the molecular chemistry of star formation. As well as producing novel scientific outcomes, these projects will feed valuable test data into the major scientific investigations slated for the SKA as it becomes operational.
A Supercomputer in the backyard
The scale of SKA, and the resultant flood of data, requires the rapid development of methods to process data. The Pawsey Supercomputing Centre – a purpose-built powerhouse named after pioneering Australian radio astronomer Dr Joe Pawsey and run by the Interactive Virtual Environments Centre (iVEC) – includes a supercomputer called Galaxy, dedicated to radio astronomy research. A key data challenge is finding ways in which the signal processing method can be split up and processed simultaneously, or ‘parallelised’, so that the full force of the supercomputing power can be used. The proximity of the signal processing experts at CIRA to iVEC means that researchers can continually prototype new ways of parallelising the data, with the goal being to achieve real-time analysis of data streaming in from the SKA.
A mammoth telescope comprising millions of antennas across Western Australia and Africa, the Square Kilometre Array (SKA) will help astronomers tackle some of the big unanswered questions of the universe.
Vast quantities of data from the telescope, due for completion in 2024, will necessitate heavy-duty computing infrastructure. The output from the Australian part alone, located at the Murchison Radio-astronomy Observatory 800 km north of Perth, will exceed a day’s Australian Internet traffic in less than 20 minutes.
The ‘brain’, called the Science Data Processor (SDP), will manage the capture of raw data at the Pawsey Supercomputing Centre in Perth and the processing and archiving of this data into a form that astronomers around the world can access.
“The main goal of the SDP is to bridge the gap between the telescope and the science,” says Vinsen’s colleague, ICRAR engineer Associate Professor Chen Wu.
ICRAR is part of the international collaboration designing the SDP – itself a multifaceted collection of hardware and software. Split into 10 work packages, the huge project is managed by 21 partners in 18 time zones with a total budget of $48.3 million. ICRAR is leading the Data Layer Work Package that will develop systems to manage the flow and storage of the telescope data.
Industrial joint-funders, such as IBM, Cisco and NVIDIA, have been involved since the project’s conception. Commercialisation of SKA technology is expected to flow naturally from the arrangement.
“There will be a significant return to industry, come what may,” says ICRAR director Professor Peter Quinn.
The SDP project, and Data Layer in particular, involves collaboration with a Chinese collective of universities, research institutes and a company. Two such partners are Tsinghua University in Beijing, who are working on data storage, and Inspur in Guangzhou, a contractor for Tianhe-2, the world’s most powerful supercomputer.
Collaboration on the SDP is part of wider investment by China in the SKA and radio astronomy in general. In a separate project, nestled in a natural bowl of limestone in the Guizhou Province in southern China, the largest single-dish telescope in the world is under construction. The Five hundred-metre Aperture Spherical Telescope (FAST) is due for completion in 2016.
The FAST design was an SKA candidate that missed out, but still promises to be a powerful telescope. ICRAR is working with the Chinese institutions involved in FAST to learn from their experiences.
“We are particularly interested in working with the Chinese on FAST because of its enormous scientific potential, but also as a precursor to the SKA technology,” says Quinn.
Extremely large optical telescopes, including the Giant Magellan Telescope (GMT), which is due to be built in Chile in 2021, will allow studies of stars and galaxies at the dawn of the universe, and will peer at planets similar to ours around distant stars.
The Square Kilometer Array (SKA), which will be constructed in Australia and South Africa over the next several years, will observe the transformation in the young universe that followed the formation of the first generation of stars and test Einstein’s theory of relativity.
Large-scale surveys of stars and galaxies will help us discover how elements are produced and recycled through galaxies to enrich the universe. The revolutionary sensitivity of the GMT will also be used to understand the properties of ancient stars born at the dawn of the universe.
On the largest scales, dark matter and dark energy comprise more than 95% of the universe, and yet their nature is still unknown. Australian astronomers will use next-generation optical telescopes to measure the growth of the universe and probe the unknown nature of dark matter and dark energy.
The long-anticipated detection of gravitational waves will also open a window into the most extreme environments in the universe. The hope is that gravitational waves generated by the collision of black holes will help us better understand the behavior of matter and gravity at extreme densities.
Closer to home, the processes by which interstellar gas is turned into stars and solar systems are core to understanding our very existence. By combining theoretical simulations with observations from the Australia Telescope Compact Array and the GMT, Australian astronomers will discover how stars and planets form.
And this far-reaching knowledge will inform new theoretical models to achieve an unprecedented understanding of the universe around us.
Over the past decade, Australian astronomers have achieved a range of major breakthroughs in optical and radio astronomy and in theoretical astrophysics.
Australian astronomers have precisely measured the properties of stars, galaxies and of the universe, significantly advancing our understanding of the cosmos. The mass, geometry, and expansion of the universe have been measured to exquisite accuracy using giant surveys of galaxies and exploding stars. Planetary astronomy has undergone a revolution, with the number of planets discovered around other stars now counted in the thousands.
In forming a strategy for the future, Australia in the Era of Global Astronomy assesses these and other scientific successes, as well as the evolution of Australian astronomy including it’s broader societal roles.
Astronomy is traditionally a vehicle for attracting students into science, technology, engineering and mathematics (STEM). The report also highlights expanding the use of astronomy to help improve the standard of science education in schools through teacher-training programs.
Training aimed at improving the “transferrable” skills of graduate and postgraduate astronomy students will also help Australia improve its capacity for innovation.
The Australian astronomy community has greatly increased its capacity in training of higher-degree students and early-career researchers. However, Australian astronomy must address the low level of female participation among its workforce, which has remained at 20% over the past decade.
The past decade has seen a large rise in Australian scientific impact from international facilities. This move represents a watershed in Australian astronomical history and must be strategically managed to maintain Australia’s pre-eminent role as an astronomical nation.
The engagement of industry will become increasingly important in the coming decade as the focus of the scientific community moves from Australian-based facilities, which have often been designed and built domestically, towards new global mega-projects such as the SKA.
While a decade is an appropriate timescale on which to revisit strategic planning across the community, the vision outlined in the plan looked beyond the past decade, recommending far-reaching investments in multi-decade global projects such as the GMT and the SKA.
These recent long-term investments will come to fruition in the coming decade, positioning Australia to continue as a global astronomy leader in the future.
This article was first published by The Conversation on 24 August 2015. Read the original article here.