tag:theconversation.com,2011:/us/topics/murchison-widefield-array-3805/articlesMurchison Widefield Array – The Conversation2023-07-19T20:00:09Ztag:theconversation.com,2011:article/2052372023-07-19T20:00:09Z2023-07-19T20:00:09ZA mysterious interstellar radio signal has been blinking on and off every 22 minutes for over 30 years<figure><img src="https://images.theconversation.com/files/535259/original/file-20230703-257103-z65saa.png?ixlib=rb-1.1.0&rect=0%2C0%2C2880%2C1621&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">The International Centre for Radio Astronomy Research</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Last year, we made an intriguing discovery – a radio signal in space that switched on and off <a href="https://theconversation.com/this-object-in-space-flashed-brilliantly-for-3-months-then-disappeared-astronomers-are-intrigued-175240">every 18 minutes</a>. </p>
<p>Astronomers expect to see some repeating radio signals in space, but they usually blink on and off much more quickly. The most common repeating signals come from pulsars, rotating neutron stars that emit energetic beams like lighthouses, causing them to blink on and off as they rotate towards and away from the Earth.</p>
<figure class="align-center ">
<img alt="A rotating pulsar" src="https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525030/original/file-20230509-23-mqcefr.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Pulsars emit powerful beams of radio waves from their poles, which sweep across our line of sight like a lighthouse.</span>
<span class="attribution"><span class="source">Joeri van Leeuwen</span></span>
</figcaption>
</figure>
<p>Pulsars slow down as they get older, and their pulses become fainter, until eventually they stop producing radio waves altogether. Our unusually slow pulsar could best be explained as a magnetar – a pulsar with exceedingly complex and powerful magnetic fields that could generate radio waves for several months before stopping.</p>
<p>Unfortunately, we detected the source using data gathered in 2018. By the time we analysed the data and discovered what we thought might be a magnetar it was 2020, and it was no longer producing radio waves. Without additional data, we were unable to test our magnetar theory.</p>
<h2>Nothing new under the sun</h2>
<p>Our Universe is vast, and so far every new phenomenon we’ve discovered has not been unique. We knew that if we looked again, with well-designed observations, we had a good chance of finding another long-period radio source. </p>
<p>So, we used the Murchison Widefield Array radio telescope in Western Australia to scan our Milky Way galaxy every three nights for several months.</p>
<figure class="align-center ">
<img alt="Spider-like dipole antennas in front of a breakaway in the outback" src="https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525036/original/file-20230509-16-8tik1t.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A single tile of the hundreds that make up the Murchison Widefield Array, a radio telescope in outback Western Australia.</span>
<span class="attribution"><span class="source">Natasha Hurley-Walker</span></span>
</figcaption>
</figure>
<p>We didn’t need to wait long. Almost as soon as we started looking, we found a new source, in a different part of the sky, this time repeating every 22 minutes.</p>
<p>At last, the moment we had been waiting for. We used every telescope we could find, across radio, X-ray, and optical light, making as many observations as possible, assuming it would not be active for long. The pulses lasted five minutes each, with gaps of 17 minutes between. Our object looked a lot like a pulsar, but spinning 1,000 times slower.</p>
<figure>
<iframe src="https://player.vimeo.com/video/826614320" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">The newly discovered mystery object emits pulses of radio waves in a 22-minute cycle.</span></figcaption>
</figure>
<h2>Hiding in plain sight</h2>
<p>The real surprise came when we searched the oldest radio observations of this part of the sky. The Very Large Array in New Mexico, United States, has the longest-running archive of data. We found pulses from the source in data from every year we looked – the oldest one in an observation made in 1988.</p>
<p>Observing over three decades meant we could precisely time the pulses. The source is producing them like clockwork, every 1,318.1957 seconds, give or take a tenth of a millisecond.</p>
<figure class="align-center ">
<img alt="Image of a radio transient switching on and off" src="https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525052/original/file-20230509-21-15gi7w.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Radio images taken with the MeerKAT radio telescope in South Africa, showing one of the pulses, sped up by a factor of 20. The other nearby radio sources remain constant.</span>
<span class="attribution"><span class="source">Natasha Hurley-Walker</span></span>
</figcaption>
</figure>
<p>According to our current theories, for the source to be producing radio waves, it should be slowing down. But according to the observations, it is not.</p>
<p>In our <a href="https://www.nature.com/articles/s41586-023-06202-5">article in Nature</a>, we show that the source lies “below the death line”, which is the theoretical limit of how neutron stars generate radio waves; this holds even for quite complex magnetic field models. Not only that, but if the source is a magnetar, the radio emission should only be visible for a few months to years – not 33 years and counting.</p>
<p>So when we tried to solve one problem, we accidentally created another. What are these mysterious repeating radio sources?</p>
<h2>What about ET?</h2>
<p>Of course, it’s very tempting at this point to reach to extraterrestrial intelligence as an option. The same thing happened when pulsars were discovered: astrophysicist Jocelyn Bell Burnell and her colleagues, who found the first pulsar, nicknamed it “LGM 1”, for “Little Green Men 1”.</p>
<figure class="align-center ">
<img alt="A chart recorder image of the first pulsar" src="https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525039/original/file-20230509-23-7udzig.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Observation of pulses from the first pulsar to be discovered, CP 1919. The chart recorder shows regular deflections every 1.3 seconds.</span>
<span class="attribution"><span class="source">Jocelyn Bell Burnell and Anthony Hewish</span></span>
</figcaption>
</figure>
<p>But as soon as Bell and her colleagues made further detections, they knew it could not be aliens. It would be incredibly unlikely for so many similar signals to be coming from so many different parts of the sky. </p>
<p>The pulses, similar to those of our source, contained no information, just “noise” across all frequencies, just like natural radio sources. Also, the energy requirements to emit a signal at all frequencies are staggering: you need to use, well, a neutron star.</p>
<p>While it’s tempting to try to explain a new phenomenon this way, it’s a bit of a cop out. It doesn’t encourage us to keep thinking, observing and testing new ideas. I call it the “<a href="https://en.wikipedia.org/wiki/God_of_the_gaps">aliens of the gaps</a>” approach.</p>
<p>Fortunately, this source is still active, so anyone in the world can observe it. Perhaps with creative follow-up observations, and more analysis, we’ll be able to solve this new cosmic mystery.</p><img src="https://counter.theconversation.com/content/205237/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natasha Hurley-Walker is funded by a Future Fellowship from the Australian Research Council.</span></em></p>Astronomers have detected a long-running source of slow, repeating radio pulses that can’t be explained by current theories – but it’s probably not aliens.Natasha Hurley-Walker, Radio Astronomer, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/663812016-10-27T01:27:12Z2016-10-27T01:27:12ZWhat the universe looks like when viewed with radio eyes<figure><img src="https://images.theconversation.com/files/143236/original/image-20161026-11239-1bqunhr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The GLEAM view of the centre of the Milky Way, in radio colour. Red indicates the lowest frequencies, green indicates the middle frequencies and blue the highest frequencies. Each dot is a galaxy, with around 300,000 radio galaxies observed as part of the GLEAM survey.</span> <span class="attribution"><span class="source">Natasha Hurley-Walker (Curtin / ICRAR) and the GLEAM Team</span>, <span class="license">Author provided</span></span></figcaption></figure><p>To the naked eye, the universe we can see on a clear night is dotted with thousands of stars, but what would it look like if human eyes could see radio waves?</p>
<p>Deep in the Western Australian outback a radio telescope is demonstrating just that by painting a picture of the cosmos in all the colours of the radio. </p>
<p>It’s called the Murchison Widefield Array (<a href="http://www.mwatelescope.org/">MWA</a>), and over the past three years astronomers have used it to perform one of the largest sky surveys of all time, covering 90% of the southern sky.</p>
<p>This is the GaLactic and Extragalactic All-sky MWA survey, or <a href="http://gleamoscope.icrar.org/gleamoscope/trunk/src/?w=2.6&l=205.5&b=-17.4&z=5">GLEAM</a> for short. If you camped out for the night in Murchison Shire, and could open your eyes to radio light, this video of GLEAM shows what you might see.</p>
<figure>
<iframe src="https://player.vimeo.com/video/188100116" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">The sky as seen by GLEAM, cross-faded with a visible-spectrum timelapse, taken above the MWA.</span></figcaption>
</figure>
<p>Unaided human vision and optical telescopes use only the visible part of the electromagnetic spectrum, a narrow window within a huge range. This optical view of the night sky shows the familiar stars of the Milky Way, and darkness where dust blocks our view of the galactic plane.</p>
<p>But GLEAM’s radio wavelengths show something completely different. With GLEAM we see that the Milky Way is glowing with synchrotron radiation, given off by high-energy electrons spiralling around magnetic fields spanning thousands of light years.</p>
<h2>Peering into the cosmos</h2>
<p>The colours that we see in GLEAM aren’t false. Red indicates the lowest radio frequencies (around the FM band of your car radio), blue indicates the highest radio frequencies (around the digital signals your TV receives), and green indicates the frequencies in between.</p>
<p>This radio colour view allows astronomers to see different kinds of physical processes going on in our universe.</p>
<p>For instance, in the galactic plane, regions of ionised plasma around the brightest stars are brighter at high frequencies and dimmer at low frequencies. These show up in blue, in contrast to the pervasive red synchrotron glow.</p>
<p>Also visible in the Milky Way are features like soap bubbles, which mark sites of ancient supernova explosions. This is where massive stars ran out of hydrogen fuel, imploded, and then exploded outward, creating a shell of radiating plasma expanding into space. </p>
<p>In the past, astronomers have found far fewer of these supernova remnants than are needed to account for the high-energy electrons that produce the synchrotron glow of the galaxy. Fortunately, GLEAM is perfectly suited to detecting these missing remnants, solving a cosmic puzzle.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/141372/original/image-20161012-8420-33qvzo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Milky Way as seen from the visible light from the left through to the radio light as revealed by GLEAM on the right.</span>
<span class="attribution"><span class="source">Natasha Hurley-Walker / Curtin University, International Centre for Radio Astronomy Research</span></span>
</figcaption>
</figure>
<p>In the image above, the inset highlights show the shell-like remains of ancient supernovae (blue box), ionised regions around bright stars (orange box), and radio jets coming from the nearby galaxy Centaurus (purple box). All of these features are undetectable in visible light. </p>
<p>Near the bottom right of the image is the Large Magellanic Cloud, our nearest neighbouring galaxy, which shines with synchrotron radio light, like the plane of our own Milky Way.</p>
<p>But it’s not just our own galaxy that this survey shines new light on. Scattered across the sky are hundreds of thousands of smaller dots. These are not stars, but distant <a href="https://theconversation.com/radio-galaxies-the-mysterious-secretive-beasts-of-the-universe-64381">radio galaxies</a>. </p>
<p>They are super-massive black holes at the cores of galaxies millions to billions of light years away. The black holes accrete matter, destroying stars, and their strong magnetic fields turn the incoming matter into massive jets of plasma, launched into space at nearly the speed of light.</p>
<p>It is this plasma that GLEAM detects, and again, the radio colour tells astronomers whether a jet is young and just starting (blue) or old and dying (red).</p>
<h2>A challenging viewpoint</h2>
<p>It wasn’t easy getting to this point. The <a href="https://theconversation.com/tuning-in-to-cosmic-radio-from-the-dawn-of-time-51584">Murchison Widefield Array</a> had to be built more than 300km from the nearest town, Geraldton, to ensure a radio-quiet environment.</p>
<p>The array consists of thousands of radio antennas, similar to TV aerials and somewhat resembling an army of mechanical spiders. These observe low-frequency radio waves, from the lowest end of the FM (72MHz) up to the highest end of the digital TV band (300MHz). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140249/original/image-20161004-20217-ti3ws9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">View of about 1% of the Murchison Widefield Array, showing the tiled dipoles used to receive astronomical signals, and a ‘beam former’, aggregating the signals and controlling the pointing of the instrument.</span>
<span class="attribution"><span class="source">MWA Collaboration</span></span>
</figcaption>
</figure>
<p>To build the survey, a team of 20 astronomers across Australia and New Zealand has painstakingly knitted together more than 45,000 images of the sky, inventing new algorithms at every turn in order to deal with the unique challenges of these data.</p>
<p>For instance, while the wide field-of-view of the MWA makes an all-sky survey possible, the ionosphere distorts the signals of every observation, <a href="https://theconversation.com/how-an-undergraduate-discovered-tubes-of-plasma-in-the-sky-42810">sometimes creating giant plasma tubes</a> that render a night unusable.</p>
<p>While the wide frequency coverage yields astronomers a scientific goldmine, it also makes source-finding and analysis more difficult. And of course, an all-sky survey isn’t small - nearly half a petabyte of data and several million CPU-hours on <a href="http://pawsey.org.au">cutting-edge supercomputers</a> went into its making.</p>
<p>The first data release was published this week in <a href="https://mnras.oxfordjournals.org/content/early/2016/09/16/mnras.stw2337.abstract">Monthly Notices of the Royal Astronomical Society</a>. It comprises a catalogue of more than 300,000 radio galaxies and images spanning 25,000 square degrees, all of which is freely accessible to the world.</p>
<p>There are yet more astronomical wonders lurking in the images such as collisions between galaxy clusters - some of the largest structures in the universe - to mysterious transient radio sources, and serendipitous discoveries that will take many eyes on the data to find. </p>
<p>A great place to start looking is the <a href="http://gleamoscope.icrar.org">GLEAM-o-scope</a>, an easy-to-use interactive viewer that gives anyone in the world the power to see the sky with radio eyes.</p><img src="https://counter.theconversation.com/content/66381/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natasha Hurley-Walker does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>To the naked eye the universe we can see on a clear night is dotted with thousands of stars. See through radio eyes, then things look very different.Natasha Hurley-Walker, Radio Astronomer, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/515842016-02-02T19:03:52Z2016-02-02T19:03:52ZTuning in to cosmic radio from the dawn of time<figure><img src="https://images.theconversation.com/files/107991/original/image-20160113-8400-hszgb7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The vast expanse of Western Australia is perfect for radio astronomy.</span> <span class="attribution"><span class="source">Pete Wheeler, ICRAR</span></span></figcaption></figure><p>Many wonders of the universe cannot be seen in visible light. Rather, we need to explore the rest of the <a href="http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html">electromagnetic spectrum</a> to reveal their splendour.</p>
<p>Some stars and galaxies emit radio waves at frequencies of hundreds of megahertz. A <a href="https://en.wikipedia.org/wiki/Hertz">megahertz</a> is one million hertz, which means one million waves pass by per second. This range is the same as many human sources of radio waves, for example our national broadcasater’s youth radio station, <a href="http://www.abc.net.au/triplej/">Triple J</a>, which broadcasts at 105.7MHz in Sydney, and 99.3MHz in Perth.</p>
<p>We also know that <a href="https://en.wikipedia.org/wiki/Hydrogen_line">hydrogen atoms emit radiation when their configuration changes</a>. The early universe consisted almost entirely of hydrogen atoms, but at some point – probably about 500 million years after the Big Bang – the first stars formed. </p>
<p>Astronomers predict we should be able to see radiation from the early universe at low radio frequencies, so we need to tune to the 80 to 300 megahertz range in order to detect this so-called <a href="https://theconversation.com/unlocking-the-mystery-of-the-first-billion-years-of-the-universe-37368">“Epoch of Reionization”</a>.</p>
<p>There are some impressive radio telescopes around the globe, including here in Australia, such as the iconic “<a href="http://www.parkes.atnf.csiro.au/">Dish</a>” in Parkes. But there’s a new kind of low frequency radio telescope, the Murchison Widefield Array (<a href="http://www.mwatelescope.org/">MWA</a>), that is based in some of the most remote regions of the outback. </p>
<p>And thanks to a <a href="http://www.arc.gov.au/news-media/media-releases/379-million-new-research-infrastructure-equipment-facilities">recent grant</a> from the Federal Government, it’s about to quadruple in size.</p>
<h2>Massive eyes on the sky</h2>
<p>The first thing most people notice about the MWA is that it doesn’t look like a traditional dish telescope such as the one at Parkes. It looks more like an army of robot spiders (see the drone video below).</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/N8MRIIIoSWY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone footage of the MWA.</span></figcaption>
</figure>
<p>The MWA consists of 2,048 antennas (the robot spiders), each of which can see almost the whole visible sky simultaneously. This is hundreds of time greater than a traditional radio telescope.</p>
<p>These eyes allow us to watch the sky constantly, monitoring it for changes. The more of the sky we can see, the more likely we are to capture rare events. For example, when the solar wind interacts with Jupiter’s magnetic field, it causes <a href="http://www.nature.com/nature/journal/v410/n6830/full/410787a0.html">massive flares</a>. </p>
<p>When this happens, Jupiter is temporarily as bright as the sun at radio frequencies. We are using the MWA to search for similar flares coming from planets in other solar systems, as well as catching a whole range of other transient events in action.</p>
<h2>Connecting the spiders together</h2>
<p>The MWA antennas are arranged in 128 groups (or tiles) spread over nine square kilometres in the Western Australian outback. This type of telescope is called an <a href="https://en.wikipedia.org/wiki/Astronomical_interferometer">interferometer</a>: the information from all of the tiles is combined together using computers, letting us create a unique picture of the sky. </p>
<p>The video below shows how the MWA interferometer is equivalent to a large single dish, but one kilometres in diameter. If you want to get a feel for its size, you can take a <a href="https://live.tourdash.com/embed/14b56659d36242dba4a1fd03813613df">Google Streetview tour of the MWA</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rfKEr2EAUlM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An illustration of how an interferometer like the MWA is equivalent to a large dish.</span></figcaption>
</figure>
<p>The tiles that are close together let us see large-scale structures on the sky, such as the <a href="http://astronomy.swin.edu.au/cosmos/S/Supernova+Remnant">shells left behind</a> when nearby stars explode as supernova at the end of their lives, as shown in the image below.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=383&fit=crop&dpr=1 600w, https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=383&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=383&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=481&fit=crop&dpr=1 754w, https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=481&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/105763/original/image-20151214-9523-pvhkzg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=481&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This false-colour MWA image shows the giant Vela supernova remnant.</span>
<span class="attribution"><span class="source">Randall Wayth/Curtin</span></span>
</figcaption>
</figure>
<p>The tiles that are farthest apart give us high resolution, letting us detect small-scale objects such as <a href="http://astronomy.swin.edu.au/cosmos/P/Pulsar">pulsars</a>. The extended MWA, spreading over roughly 20 square kilometres, will improve these capabilities, giving us an incredible picture of both our own <a href="http://astronomy.swin.edu.au/cosmos/M/Milky+Way">Milky Way galaxy</a> and the distant universe.</p>
<h2>A radio quiet home</h2>
<p>Modern society is full of <a href="http://spectrum.ieee.org/telecom/wireless/electronic-noise-is-drowning-out-the-internet-of-things">radio-emitting devices</a>: mobile phones; microwaves; and even Fitbits. To detect weak signals from space the MWA has to be extremely sensitive. But this means it can also pick up the radio emission from all our devices. </p>
<p>To overcome this problem the MWA was built in a <a href="http://ska.gov.au/Observatory/Pages/RadioQuiet.aspx">Radio Quiet Zone</a>, which means that no radio-emitting devices are allowed. Computers and other essential engineering tools are shielded in a <a href="http://www.atnf.csiro.au/projects/askap/news_mro_14122012.html">specially designed building</a>.</p>
<p>The Western Australia outback is one of the best places in the world you could build the MWA, and in the future this site will become the home of the <a href="https://www.skatelescope.org/">low frequency Square Kilometre Array</a>.</p>
<h2>An incredible telescope</h2>
<p>The upgraded MWA has an ambitious science program, but perhaps more exciting is the prospect of discovering something unexpected. We saw the first example of this last year, when undergraduate student <a href="https://theconversation.com/how-an-undergraduate-discovered-tubes-of-plasma-in-the-sky-42810">Cleo Loi</a> used the telescope to image “waves in the sky”: incredible plasma structures in the Earth’s ionosphere, as shown in the video below.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ymZEOihlIdU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cleo Loi’s discovery of “plasma tubes” in the ionosphere with the MWA.</span></figcaption>
</figure>
<p>The challenges of building facilities on the edge of technology and innovation, like the MWA, in an environment like the Murchison region, are extreme, but worth it. </p>
<p>Uncovering a deeper truth about the universe is what drives science and scientists. This, in turn, helps drive the technology development that is critical for an economy based on innovation. This is where Australia needs to be in decades to come and challenging, fundamental projects like the MWA will help us get there.</p><img src="https://counter.theconversation.com/content/51584/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tara Murphy works for the University of Sydney. She receives funding from the Australian Research Council through the Centre for All-Sky Astrophysics (CAASTRO).</span></em></p><p class="fine-print"><em><span>Steven Tingay receives funding from Curtin University, Western Australian Government, Australian Government, US Government. He is a member of the ALP.</span></em></p><p class="fine-print"><em><span>Randall Wayth works for Curtin University. He receives funding from the Australian Research Council and Western Australian government through the ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) and the International Centre for Radio Astronomy Research (ICRAR). </span></em></p>The Murchison Widefield Array sits in remote Western Australia far from noisy civilisation so it can help us understand the universe by tuning into radio waves from the distant cosmos.Tara Murphy, Associate Professor and ARC Future Fellow, University of SydneySteven Tingay, Professor of Radio Astronomy, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/428102015-06-05T04:43:17Z2015-06-05T04:43:17ZHow an undergraduate discovered tubes of plasma in the sky<figure><img src="https://images.theconversation.com/files/84032/original/image-20150605-3381-uher5d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A 3D visualisation of the plasma tubes conforming to the Earth's magnetic field.</span> <span class="attribution"><span class="source">CAASTRO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The discovery by an undergraduate student of <a href="http://caastro.org/news/2015-tubes">tubes of plasma drifting above Earth</a> has <a href="http://www.smh.com.au/technology/sci-tech/astronomy/sydney-university-physics-undergraduate-maps-huge-plasma-tubes-in-the-sky-20150601-ghcc9g.html">made headlines</a> in the past few days. Many people have asked how the discovery was made and, in particular, how an undergraduate student was able to do it.</p>
<p>The answer is a combination of an amazing new telescope, a very smart student and an unexpected fusion of two areas of science. </p>
<p>Here is how it all happened, from my perspective as the academic who supervised the project at the <a href="http://sydney.edu.au/science/physics/sifa/">Sydney Institute for Astronomy</a>.</p>
<p>My research involves studying the variability of stars and galaxies using a new radio telescope, the <a href="https://www.facebook.com/Murchison.Widefield.Array">Murchison Widefield Array</a> (MWA). My colleagues and I were worried about the <a href="http://solar-center.stanford.edu/SID/activities/ionosphere.html">ionosphere</a> being a problem for this research, because at low frequencies it can distort the radio signals that we receive from outer space. </p>
<p>This makes celestial objects appear to jiggle around, be stretched and squeezed, and change in brightness. I knew this would be a problem for my plan to study how the brightness of stars and galaxies varied, so I wanted to find out how severe the distortion was.</p>
<p>The ionosphere is the part of the Earth’s atmosphere that has been ionised by radiation from the sun. It is made up of a <a href="http://en.wikipedia.org/wiki/Plasma_%28physics%29">plasma</a> in which the gas molecules have lost one or more electrons. It stretches between 50 to 1,000 kilometres above the Earth’s surface (commercial aeroplanes typically fly at 10 kilometres above the Earth). Importantly, it refracts radio waves, affecting radio communication around the world.</p>
<p>At the beginning of last year I had a final-year undergraduate student, Cleo Loi – who also contributed to this article – looking for a research project, so I gave her the task of investigating how much the ionosphere was affecting astronomical observations with the MWA.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ymZEOihlIdU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Watch Cleo explain her amazing discovery.</span></figcaption>
</figure>
<h2>Strange distortions</h2>
<p>Around that time, a postdoctoral researcher from Curtin University, <a href="http://www.icrar.org/contact/academic_staff/dr-natasha-hurley-walker">Natasha Hurley-Walker</a>, was examining MWA data and came across a night that looked rather unusual. </p>
<p>Celestial objects were dancing around wildly, distorting strongly in shape and flickering in brightness. She flagged this night as one that the ionosphere had rendered unusable for our astronomy research.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5KWGDx0fq50?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The distortions caused by the ionosphere in a particularly bad night of data. The bright points are distant galaxies that appear to move and flicker. On a normal night these would be stationary.</span></figcaption>
</figure>
<p>Cleo then developed a way of visualising the distortions caused by the ionosphere on the images of distant background galaxies. She took the data Natasha had identified and applied her analysis to it. </p>
<p>When she showed me and other researchers the distortion maps she was generating, we were surprised to see huge waves of correlated motion rippling through the image. They looked like spokes radiating from a point outside the image.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/rYXuZsNWGmg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cleo’s original visualisation. The red and blue arrows show the apparent change in position of the background sources.</span></figcaption>
</figure>
<h2>Looking for answers</h2>
<p>To try to work out what they were, Cleo transformed the coordinates from a celestial reference frame (that astronomers usually use) to an Earth-based reference frame, which is fixed with respect to the atmosphere. This crucial transformation revealed that the bands were hanging almost stationary in the Earth’s sky.</p>
<p>In the process of writing up our research, we emailed Cleo’s preliminary results to collaborators. The MWA collaboration consists of hundreds of radio astronomers and engineers from Australia, New Zealand, the United States, India and Canada. They were quick to respond with a list of suggestions as to what the bands might be. </p>
<p>It is a critical part of science that good scientists respond to unexpected results with scepticism, particularly if they come from an inexperienced student. But the sheer volume of emails was initially quite overwhelming for Cleo. However, she stayed focused on solving the problem. </p>
<p>The suggestions ranged from possible problems with the telescope, the observing set-up, the imaging process and Cleo’s analysis techniques. Hundreds of emails were exchanged over a few months as Cleo tested and ruled out each suggestion.</p>
<p>Once we had run out of things to test we were left with an interesting dataset, an unexplained phenomenon and an increasing suspicion that the strange distortion pattern was a real effect caused by the ionosphere.</p>
<p>As she was preparing her honours thesis, Cleo had a geometrical insight into explaining the radial spoke-like pattern. She realised that a set of parallel lines viewed at an angle would appear to converge due to perspective distortion, like train tracks going into the distance. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-A3YjUL9JAI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A map of the tubular structure in two dimensions. The black lines are the Earth’s magnetic field.</span></figcaption>
</figure>
<p>However, without much knowledge of <a href="http://en.wikipedia.org/wiki/Geophysics">geophysics</a>, it was several weeks until she made a second critical link: the layout of the spokes matched the Earth’s magnetic field. These strange tubular structures were tracing the magnetic field lines, which are parallel to one another but at an angle to the ground. The agreement was perfect.</p>
<h2>Stereo vision</h2>
<p>Armed with solid evidence, Cleo and I got in touch with geospace physicists to help us interpret what we were seeing. Suggestions to explain the phenomena included plasma bubbles, travelling ionospheric disturbances and ultra-low-frequency waves. </p>
<p>Finally, <a href="https://www.newcastle.edu.au/profile/fred-menk">Fred Menk</a> from the University of Newcastle suggested they might be “whistler ducts”. These are cylindrical structures aligned to a magnetic field, where the electron content is higher inside than outside. They are thought to guide the propagation of electromagnetic waves called “whistlers” in the same way that optic fibres guide light.</p>
<p>Whistler ducts had never been seen before, but all their properties deduced by scientists over the years matched what we were seeing with the MWA. Except for one thing: we didn’t know how high they were. </p>
<p>Until now, we had only used the MWA to take two-dimensional pictures of the sky. Whistler ducts exist at very high altitudes, and an altitude measurement was necessary if we were to confirm them as a known phenomenon. </p>
<p>Cleo was reluctant to publish the result without an altitude estimate. However, we couldn’t derive that from our data, so we encouraged her to publish the results as they were. </p>
<p>At that point Cleo had a brainwave. She realised that the MWA could be used stereoscopically to achieve 3D vision, like a giant pair of eyes. By splitting the data from the eastern and western receivers of the MWA, she revealed a slight parallax shift in the distortion pattern that let us triangulate the altitude: around 600km above the ground. </p>
<p>We were all astounded that this idea had worked, confirming that these were likely to be whistler ducts.</p>
<p>It has been an exciting year of research. We started out with an astronomy question and found a surprising answer in geospace physics. To the layperson, these might seem like the same field, but to scientists focused deeply within their narrow field of expertise, the gap is wide.</p>
<p>Cleo has shown how a talented but novice researcher can have an advantage over experienced researchers. By approaching the problem without preconceptions she was able to bridge these two disciplines and use a novel technique on a new radio telescope to discover plasma tubes in the sky.</p><img src="https://counter.theconversation.com/content/42810/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tara Murphy works for the University of Sydney. She receives funding from the Australian Research Council through the Centre for All-Sky Astrophysics (CAASTRO).</span></em></p><p class="fine-print"><em><span>Cleo Loi does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Cleo Loi was an undergraduate when she made a startling discovery. Her story shows how brilliance, dedication and imagination drive science.Tara Murphy, Senior Lecturer, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/112212013-01-07T13:39:42Z2013-01-07T13:39:42ZAspiration vs delivery: the long road to the Square Kilometre Array<figure><img src="https://images.theconversation.com/files/18817/original/j968mgkg-1355790851.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The SKA is on the horizon, but how do we get from here to there?</span> <span class="attribution"><span class="source">Pete Wheeler, ICRAR</span></span></figcaption></figure><p>The <a href="http://skatelescope.org">Square Kilometre Array (SKA)</a> radio telescope has been on the cards since the early <a href="http://www.skatelescope.org/the-project/history-of-the-organisation/">1990s</a>. It took until May of last year to find out where it will be built – <a href="https://theconversation.com/splitting-the-ska-why-a-dual-site-setup-is-a-win-for-everyone-7273">in South Africa, Australia and New Zealand</a> – and it will be another seven years until the first science starts coming out of the facility.</p>
<p>So what are the challenges facing the development and construction of the SKA? And what can we learn from existing projects to ensure a smooth development and roll-out for the SKA?</p>
<h2>A complex instrument</h2>
<p>Once constructed, the SKA will be a <a href="https://theconversation.com/explainer-radio-astronomy-7420">radio telescope</a> with a collecting surface area (equivalent to the lens or mirror in an optical telescope) of one square kilometre.</p>
<p>This collecting area will be made up of thousands to millions of small radio telescopes, scattered over at least hundreds of kilometres (using a technique called <a href="http://en.wikipedia.org/wiki/Interferometry">interferometry</a>). These telescopes will be connected together with super-high-speed optical fibre and data will be fed into what will be the <a href="http://www.info.gov.za/aboutgovt/programmes/ska/index.html">biggest supercomputer in the world</a>.</p>
<p>The SKA will be sensitive enough to study normal <a href="http://en.wikipedia.org/wiki/Galaxy">galaxies</a> billions of light years away, thereby allowing the study of the structure and evolution of the universe. We hope this will start to reveal the nature of <a href="https://theconversation.com/adventures-in-the-dark-side-of-cosmology-1455">“dark energy” and “dark matter”</a> – mysterious but apparently fundamental constituents of the universe. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8BBoDw2qVD0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>But before the science gets underway, there are a number of clear challenges that need to be overcome:</p>
<ul>
<li>the SKA is a complex consortium of nine financial member countries which bring varying degrees of funding, expertise and capacity to the table</li>
<li>the project will be executed on three sites in three separate countries (with a head office in a fourth country)</li>
<li>the <a href="http://www.skatelescope.org/the-science/">science goals</a> are many and varied</li>
<li>four different base telescope technologies are included in the high-level design</li>
<li>technical and engineering boundaries will be simultaneously pushed in multiple directions</li>
<li>the final design and construction phases will span more than ten years, and</li>
<li>the project is not yet fully funded.</li>
</ul>
<p>These challenges are why we pursue projects such as the SKA. The SKA is an example of global mega-science, internationally focused on the biggest questions facing physics, fostering maximum technical innovation and encouraging future generations of scientists, engineers and computer programmers to take on large and complex problems.</p>
<p>The international community is smart enough not to launch into a project such as the SKA without taking some “baby” steps. Thus, a number of serious SKA pathfinder telescopes are being built.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=366&fit=crop&dpr=1 754w, https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=366&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/18657/original/h5zvt3gr-1355379505.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=366&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">ASKAP, CSIRO’s SKA pathfinder at the Murchison site, will help scientists to tackle some of the biggest questions in radio astronomy.</span>
<span class="attribution"><span class="source">Alex Cherney</span></span>
</figcaption>
</figure>
<h2>Finding our way</h2>
<p>Two pathinders are being built in Western Australia – the <a href="http://www.atnf.csiro.au/projects/mira/">Australian Square Kilometre Array Pathfinder</a>, and the <a href="http://www.mwatelescope.org/">Murchison Widefield Array</a> (MWA) – one is being built in South Africa – <a href="http://www.ska.ac.za/meerkat/">MeerKAT</a> – and one is being built in The Netherlands, called <a href="http://www.lofar.org/">LOFAR</a>. </p>
<p>These prototypes are being used to ensure the technology used in the SKA will work, and also to help further refine and develop such technology. In fact, between them, the four pathfinders cover three of the four SKA telescope technologies.</p>
<p>Now that the site decision has been made, the SKA project enters a four-year final design stage. During this period, the pathfinder telescopes will come online.</p>
<p>The intention is that the experience in constructing and operating the pathfinders will inform the final SKA design. There are a vast number of things to learn from the pathfinders (especially those in Western Australia and South Africa) on the engineering, science and computing fronts.</p>
<p>The MWA and LOFAR aim to get the first hints regarding the formation of the first stars and galaxies in the universe, more than 13 billion years ago. These first results will guide the final specifications for the SKA in taking the next big step: imaging structure formation in the early universe in great detail. </p>
<h2>On the right track</h2>
<p>I’m the Project Director for one of the pathfinder telescopes, the <a href="https://theconversation.com/more-than-mining-why-western-australia-is-perfect-for-radio-astronomy-and-the-ska-5750">MWA</a>, which has reached the point of construction completion and was formally launched at the end of November 2012.</p>
<p>The MWA will be the first pathfinder operational for science on either of the two SKA sites, from early 2013.</p>
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<figcaption>
<span class="caption">Some of the 128 aperture array “tile” antennas of the Murchison Widefield Array, a pathfinder for the low frequency SKA.</span>
<span class="attribution"><span class="source">MWA Project</span></span>
</figcaption>
</figure>
<p>The parallels between the MWA and the SKA are more than passing. </p>
<p>The MWA has been built by a complex consortium of 13 institutions from four countries. We have learnt a lot about the costs and benefits of a highly distributed workforce and we believe these lessons are applicable to the SKA.</p>
<p>The MWA project is a <a href="http://en.wikipedia.org/wiki/Murchison_Widefield_Array#Science">low-frequency telescope</a>, same as the main component of the SKA that will come to Western Australia. Indeed the MWA has been built on the SKA site. We have learnt a lot about building low-frequency telescopes in the exact physical conditions the SKA will experience.</p>
<p>The MWA has science goals ranging from observations of the sun to observations of the early universe when the first stars and galaxies formed. Like the SKA, we have had to balance the demands of a wide range of science goals.</p>
<p>Only in the last 12 months of the MWA construction project did we understand our final budgetary envelope. This means we’ve had great experience designing to cost, strategically scoping the project, managing risks, engaging industry partners, managing stakeholder expectations and scheduling work.</p>
<p>The SKA is in the same boat with respect to its funding and the project will need to get started on design and prototyping before understanding how much money is available for construction.</p>
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<figcaption>
<span class="caption">Deploying some of the MWA infrastructure at the Murchison site, reticulation of power and optical fibre to support the array of antennas.</span>
<span class="attribution"><span class="source">MWA Project</span></span>
</figcaption>
</figure>
<h2>Separate, but together</h2>
<p>One of the big lessons we’ve learnt with the MWA is to seek, where possible, to decouple different elements of the project from each other to reduce dependencies and allow different parts of the work to proceed in parallel. In doing this, we had to retain flexibility of design, to react to changing financial conditions.</p>
<p>For the low-frequency component of the SKA, a big lesson learnt from the MWA was that the supporting infrastructure (a big cost and risk driver because it has a long lead time, requires a large number of contractors and sub-contractors, and is subject to wider market forces such as the construction industry) could be largely decoupled from the problem of the exact placement of antennas.</p>
<p>Inherent in the design of low-frequency antenna arrays is the flexibility to undertake some of the heavy work of infrastructure deployment (joining of power and optical fibre, on-site buildings and high-speed data transport) in parallel with finalisation of the design and placement of the antennas.</p>
<p>While I think we have learnt many lessons from the MWA, this is the biggest lesson that helped us toward delivery. If applied to the SKA, decoupling infrastructure and instrument will make the most of the natural advantages of the low-frequency technologies, reduce risk and may collapse the overall schedule (and cost).</p>
<p>It’s been more than two decades since the SKA concept first emerged and it will be another decade until the facility is operating at its planned full capacity.</p>
<p>There is, of course, much work to be done between now and then, but if we take into account similar existing and ongoing projects, we’ll give ourselves the best chance of a smooth SKA roll-out.</p>
<p><em>I acknowledge the Wadjarri Yamatji people as the traditional owners of the land on which the MWA has been built.</em></p><img src="https://counter.theconversation.com/content/11221/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven Tingay receives funding from Curtin University, the Western Australian Government and the Australian Government (including via the Australian Research Council and Astronomy Australia Limited). He works for Curtin University.</span></em></p>The Square Kilometre Array (SKA) radio telescope has been on the cards since the early 1990s. It took until May of last year to find out where it will be built – in South Africa, Australia and New Zealand…Steven Tingay, Professor of Radio Astronomy, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/99912012-10-05T03:01:35Z2012-10-05T03:01:35ZCSIRO launches the ASKAP telescope – and a new chapter for radio astronomy begins<figure><img src="https://images.theconversation.com/files/16206/original/ckjr74qt-1349343981.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ASKAP will help scientists to tackle some of the biggest questions in radio astronomy.</span> <span class="attribution"><span class="source">Alex Cherney</span></span></figcaption></figure><p>Today, after several years of design and construction, CSIRO’s <a href="http://www.atnf.csiro.au/projects/mira/">Australian Square Kilometre Array Pathfinder (ASKAP)</a> is officially open.</p>
<p>The A$140m facility, built in the remote <a href="http://www.murchison.wa.gov.au/">Murchison Shire</a> of Western Australia, has a dual role as a cutting-edge radio telescope to study the universe and as a technology demonstrator for the planned A$2 billion <a href="https://theconversation.com/topics/square-kilometre-array">Square Kilometre Array (SKA)</a>.</p>
<p>ASKAP comprises 36 radio dishes, each with a diameter of 12 metres, making the telescope sensitive to faint radiation from the Milky Way and giving it the ability to detect very distant galaxies. It is also a remarkably complex telescope.</p>
<p>A new receiver technology called a <a href="http://www.atnf.csiro.au/projects/mira/smart_feeds.html">phased array feed</a>, developed in Australia by CSIRO, gives ASKAP an unrivalled capability to survey large volumes of the cosmos. </p>
<p>These special cameras increase the area of sky visible to the telescope at any one time by a factor of 30 over existing technology. This increases the scale of the resulting photographs of the <a href="https://theconversation.com/explainer-radio-astronomy-7420">radio sky</a> from the size of the full moon to an area larger than the Southern Cross.</p>
<p>The addition of this wide-angle camera boosts the survey speed of ASKAP, allowing astronomers to carry out large “drift-net” surveys, to trawl the sky and gather information on hundreds of millions of galaxies. </p>
<p>By working in this way, the telescope is able to tackle big-ticket research areas such as <a href="https://theconversation.com/topics/cosmology">cosmology</a> and <a href="https://theconversation.com/adventures-in-the-dark-side-of-cosmology-1455">dark energy</a> and gather enough statistical information to study the fascinating life stories of galaxies.</p>
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<figcaption>
<span class="caption">It’s been several long years of design and construction, but ASKAP is open for business.</span>
<span class="attribution"><span class="source">Alex Cherney</span></span>
</figcaption>
</figure>
<p>Researchers from around the world are already lining up to use the facility with ten ASKAP science survey teams, totalling more than 700 astronomers, ready and waiting. </p>
<p>These teams are working with CSIRO to design and maximise the scientific value of the surveys, some of which will take around two years to complete. Science verification has begun and some science projects are expected to be underway by the end of 2013.</p>
<p>CSIRO and the science teams are also tackling head-on the challenges involved in extracting – in real-time – scientific knowledge from an extremely large (72 Terabit per second) raw data stream. That’s enough to fill 120 million Blu-ray discs per day.</p>
<p>Dealing with such data volumes is something radio astronomers will have to get used to. In the era of the SKA we will find ourselves interacting less with real telescopes and more often mining online data stores and “virtual observatories”. Not only is the technology changing, the way in which we do our science is also being transformed.</p>
<p>One of the aims of the SKA Pathfinders (the others being the <a href="http://www.ska.ac.za/meerkat/">MeerKAT facility</a> in South Africa and the <a href="http://astronomy.curtin.edu.au/research/mwa.cfm">Murchison Widefield Array</a>) is to ensure the next generation of astronomers is ready for this new challenge.</p>
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<p>The official opening of ASKAP and the <a href="http://www.astro.uwa.edu.au/ska/mro">Murchison Radio-astronomy Observatory (MRO)</a> marks the beginning of a new chapter for radio astronomy in Australia. Following the announcement earlier this year of a <a href="https://theconversation.com/the-square-kilometre-array-finally-has-a-home-or-two-7274">dual-site arrangement for the SKA</a>, we now know the MRO will host two complementary astronomical instruments during <a href="http://www.skatelescope.org/about/project/">Phase 1 of the project</a>.</p>
<p>One will study low-frequency radio waves emanating from cold gas in the early universe and will build on the scientific and technical expertise gained from the Murchison Widefield Array project. The other will be an array of almost 100 dishes built on the capabilities of ASKAP. This instrument will be used to survey unprecedented volumes of our universe and delve even deeper into it’s secrets.</p>
<p>Over the coming decade the number and capabilities of telescopes available to radio astronomers will grow enormously. Along with the Murchison Widefield Array, ASKAP is leading the way in prototyping cutting-edge SKA technologies at the most <a href="https://theconversation.com/more-than-mining-why-western-australia-is-perfect-for-radio-astronomy-and-the-ska-5750">radio-quiet</a> observatory on Earth.</p>
<p>It truly is an exciting time to be a radio astronomer! </p>
<p><strong>CSIRO acknowledges the Wajarri Yamatji people as the traditional owners of the land on which the observatory was built.</strong></p><img src="https://counter.theconversation.com/content/9991/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lisa Harvey-Smith works for CSIRO and is project scientist for ASKAP.</span></em></p>Today, after several years of design and construction, CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) is officially open. The A$140m facility, built in the remote Murchison Shire of Western…Lisa Harvey-Smith, Australian Square Kilometre Array Pathfinder (ASKAP) Project Scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.