The Square Kilometer Array: radio silence in Western Australia for most powerful telescope in history
In outback Western Australia, around 350k northeast of the small town of Geraldton, lies an area of land about the size of the Netherlands, but with only 100 humans living in it: the shire of Murchison.
The land looks beautiful but far from unusual as you head up the long red road north – mostly pancake flat and scrubby, with here or there the spark of a winter flower, a kangaroo or a sudden, luminous outcrop.
But this is an extremely unusual place, rich in something very precious: radio quiet. This is where you will find the Murchison radio-astronomy observatory (although drop-ins are heavily discouraged), spread out over many kilometres of what used to be a simple cattle farm.
Murchison is already arguably the most happening radio astronomy site in Australia, and soon it will be home to the most expensive and advanced radio astronomy project in the history of humankind: the Square Kilometre Array (SKA).
Once the project is properly under way – with arrays at this site and another in a remote area of South Africa – it will in effect make up the biggest radio telescope the world has seen. At Murchison alone there will be 130,000 radio antennas in the first phase, and maybe a million in the second, taking care of the lower frequency end of the project.
The telescope will be perhaps 10,000 times more powerful than any we currently have, and we will need a supercomputer more advanced than anything yet built to analyse the data it produces. Right now we can spot planets circling around distant stars. The SKA will be able to spot the equivalent of an airport radar system on one of those very, very distant planets.
It will also allow us to dig down into the ancient history of our universe, and there’s no knowing what it will find there, or what it will mean for us.
On SKA’s website, there is a list of five things the telescope will look into, but as Dr John Morgan, a tall, cheerful astronomer from Curtin University, puts it: “You can guarantee that the thing that SKA will be remembered for – is not on that list. It’s going to be the thing you have not thought of. It’s the unknown unknown.”
The thing that SKA will be remembered for … is going to be the thing you have not thought of
Dr John Morgan
If you’re studying radio waves – really old, weak ones from the dawn of the universe – what you don’t want is lots of people making very loud radio noise really close up. And visitors inevitably make radio noise because they use electronic devices, and all electronic devices make radio waves.
A car starting or an electronic camera clicking or a mobile phone searching for reception are much louder to the equipment here than any distant galaxy. Obliterating, even.
But people need to work at the site, at least during the day, and others need to visit.
So visitors must be prepared for, scheduled in and accounted for when looking at the data this place produces. Long before you get to Boolardy, the 346,000-hectare pastoral station on which the Murchison observatory stands, the radio-quiet restrictions start. Anyone approaching is asked to turn off all electronic devices (nothing can be done about the cars).
At Boolardy homestead, the base camp for the observatory, there is strictly no wifi (although it has excellent internet access thanks to the large internet cable that for operational reasons runs between the site and Geraldton). Televisions are brutally stripped of their wifi and bluetooth capabilities here before anyone is allowed to turn them on.
And this is still 45 minutes’ drive from the site proper, which is protected from radio noise by most everything state and federal legislation can throw at it. The site, the ancestral home of the Wajarri Yamatji people, is largely empty bush, but it has a bunch of different arrays, peeking here or there from the scrub or, in the case of its 36 big white dishes, towering grandly over the land.
All the data collected from the different kinds of antenna and dishes, gets a first process on the site. It’s transformed from analogue to digital signals by two highly specialised super-computers before getting shipped downstream to Geraldton and then south to the Pawsey super-computing centre in Perth .
Super-computers do make radio noise, so the on-site control centre is wrapped in two radio-proof skins. There are even special filters on the air vents.
To get to the computers you need to go through two “radio locks”, carefully closing the door behind and huddling in a dim and claustrophobic space until you’re allowed to open the next door. It’s a long way to go out if you need the toilet. But the radio pollution from the on-site control centre is close to zero.
There are other factors that make the site special: it has a great view of the galactic centre of the Milky Way, as well as being a good distance from both the south pole and the equator, to limit disruption from the ionosphere.
On Tuesday Karen Andrews, the parliamentary secretary to the minister for industry and science – the minister now directly responsible for SKA in Australia – visited the site for the first time.
For any government, the attractions of SKA are obvious: the “enormous prestige”, as Andrews puts it, of playing host to such a global and historic project; the jobs it may deliver; and the potentially lucrative innovation the outpouring of data will produce.
“If we look at the jobs of the future we don’t know precisely what they are going to be,” Andrews says. “But it’s pretty clear … that there’s a lot of work for people who can analyse data. What we need is to make sure is that we have our jobs of the future focused on where we’re going to need them.”
Accompanying Andrews was Prof Peter Klinken, the chief scientist of Western Australia – the state will need to keep backing this project hard. Also there was Patricia Kelly, the woman who will represent SKA, on behalf of Australia, at a global level. The project will soon require international treaty negotiations before the build phase starts in earnest in 2018.
Also with them was a clutch of journalists and scientists; all the scientists were closely involved with SKA, or will be. Dr Lewis Ball, director of astronomy at the CSIRO, Australia’s science agency, was there, as was Prof Carole Jackson of Curtin university, who has been heavily involved in every stage of preparation for SKA. Ball, who carefully calibrates his statements, describes SKA as “the biggest science project in the world likely to happen in the next 20 years”.
Complex – but awesome
Ten countries are currently involved in SKA – the headquarters are at Jodrell Bank in Britain – and Australia has spent years preparing for it. It needed to position itself carefully to ensure its place as a host country. Everything at Murchison has been done in preparation for SKA, on what the various scientists describe as a “no regrets” basis. If SKA hadn’t happened, well, they’d still be doing great science here.
This is the kind of massive, generational, global scientific project – involving universities, science agencies, private companies, a host of governments – that takes decades to come about, and can come to define departments, careers, national identities, science itself. In Australia alone, the project involves so many different groups and so many different acronyms that it can take a while to get your head around it all, but this, all the scientists say, is the nature of large, international endeavours. “It is complex,” says Dr Jill Rathborne, a CSIRO astronomer. But it’s also “awesome”.
That’s the fun of all this – working things out
The different types of antennas at the site stand testament to the complexity of what has already gone on and what lies ahead. The most obviously magnificent array is a wide-flung group of 36 big white dishes, of the sort all sci-fi film buff would recognise as relatives of those Jodie Foster controlled in Contact (but more modern, of course). The name square kilometre array is meant to refer to the total effective surface area of the dish that would equate to the finished SKA telescope arrays … except actually it doesn’t any more, now that the idea for SKA has been around for about 25 years. It’s really a terrible name.
Six of them are up and running, using innovative technology that allows the dishes to focus on a much wider area of sky than previously. These dishes, called the Australian Square Kilometre Array Pathfinder (Askap – another of the many awful acronyms involved) were built by the CSIRO. At some point, they may be folded into the main SKA project. In an earlier draft of the plan they were meant to be in the first phase, but then the SKA plan was “rebaselined”, which means that it was more realistically costed. But they are here, and real, and already collecting data.
Over a bright red outcrop, in a different area of this space farm, lies another array – the spiders, also known as the Murchison Widefield Array . There are low-lying, silver patches of them all over the ground here, each with a lead snaking off towards the control centre.
“The world’s best low frequency telescope,” Carole Jackson calls them. They are looking at the “very oldest radiation in the universe”, she says, and are “quite revolutionary”.
The spiders exist as a direct precursor of the SKA army to come. For a super-high-tech radio antenna array they are surprisingly basic-looking. Scientists lean on them as we inspect them in a very casual way. But the team says spiders are deliberately low-tech and low cost.
The spiders (there are 2,048 of them) are simple because “the smarts are in the back end”, Jackson says. They are controlled by a consortium of scientists from several international universities, led by Curtin university, and are already providing a lot of data on the very earliest days of the universe, the first billion years, the “unexplored epoch” . The data is helping the teams prepare for SKA.
The spiders also allow scientists to test the development of the other key array here: the Christmas trees. These are, to the amateur eye, a bit of a sorry-looking bunch. There is only one small clump of them.
The scientists among the assembled visitors discuss who is to thank for the “coat hanger” design, and agree: “Cambridge.”
But sorry-looking or not, these are the future of radio astronomy. Tweaked and retweaked (currently they wobble in the wind, which is not ideal), they will in some future form be the radio antennas for the SKA project. Soon these Christmas trees will spread and spread across this land into a great metal forest – and change our understanding of the universe.
Faith in computers of the future
Companies such as Cisco and IBM are keenly interested in SKA and that’s because of the data, and what will be needed to crunch it. Once SKA is fully up and running, it will produce more information each day than the whole of the internet had produced until very recently.
Given that no computer exists that will be able to deal with the volume of what SKA will produce, the success of the project rests on the continuing robustness of Moore’s law : that every 18 to 24 months computer processing power will double.
Moore’s law is quoted very often by the project team. The universe needs to keep bending a knee to it if the data from SKA is going to be of any use to us.
It may sound like a massive leap of faith to a non-scientist, preparing to gather data with no way yet to analyse it, but as Morgan says: “If we built it for a computer we have today, we’ll be selling ourselves short … massively short. You have to look at the trends, very stable trends on how computers are progressing.”
There will be far too much data for it all to be simply recorded. The plan is to “use an algorithm to reduce that data down to a smaller magnitude that you can then process further on a super computer”, Morgan says. The detail obviously hasn’t been worked out yet, but “at some point we’ll switch this thing on and it’ll take us a long time to see how it works”.
When the time comes, the team will have one problem rather more prosaic than building a super-supercomputer: the cows. If they build a million Christmas trees, they won’t be able to afford to build a fence to protect them, because they’ll take up a great deal more space than a square kilometre.
So how will they keep the cows off these fairly vulnerable constructions? “Well we’ll work something out,” one of the team says. “That’s the fun of all this – working things out.”
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