Sunday, April 28, 2013

SKA well underway [Original Article]

If you build it, they will come.  Since South Africa won the giant’s share of the SKA bid, construction is going at full steam and hundreds of people are involved, both locally and from around the world, as Nick van der Leek reports.

From Hartebeesthoek to Stellenbosch, from Grahamstown to Carnarvon, South Africa’s Square Kilometre Array team are very busy behind the scenes, designing, engineering and building the world’s largest and most advanced space camera.  That’s what the SKA is – thousands of small antennas surveying the sky like a giant eye, but at the incredible resolutions typical of radio astronomy and also more than ten thousand times faster than previously possible.  But the images are far more detailed than a mere camera image, and as a result, the data used to build these images has to be received, conveyed, processed and stored.  What’s exciting is that the drive to build these new technologies will eventually have applications downstream – to the man in the street.  When you use Bluetooth on your phone or laptop, or pick up the remote control to change a channel – you’re using legacy technology courtesy of radio astronomy.  The SKA means much more is in store.

Although it seems complicated, the process is fairly simple.  Labs around the country are working to design both antennas (which find and track the target in space) and receivers (which begin the processing of the signal from the target, which is reflected off a dish. In the Cape, Stellenbosch University is actively involved in the engineering work that goes into getting crystal clear (undistorted) signals, whilst a company called EMSS, also in Stellenbosch, is building the antennas and the housings that attach to the dish.

Prof David Davidson from Stellenbosch University: "The main job of the Stellenbosch research chair is to produce highly-trained engineers on mission-critical electronic engineering technologies for MeerKAT and SKA. This includes: the simulation and design of the dish; feed and receivers; signal processing; calibration; and radio frequency interference mitigation. Many of these graduates are already making a difference in industry." 

Isak Theron, Technical Director at EMSS: We design the receivers, cryostats and feed horns (the small antennas at the focus of the dish). We are… [also] involved in specifying the shape of the reflecting surfaces.”

An interesting recent development comes from IBM: they have signed a 4 year deal to collaborate with the SKA in researching extremely fast, but low-power exascale computer systems.  A Dutch Institute for Radio Astronomy, Astron will also be involved. The global reach of the SKA is impressive.  Though the centrepiece of the array is at a site about 85 kilometres from Carnarvon in the Northern Cape, the SKA itself is headquartered in Manchester, England, and has around a dozen members, with Germany one of the most recent. South Africa and to a lesser extent Australia, are both involved in providing the actual radio quiet sites essential for radio astronomy.

One of the most surprising aspects of the SKA are the processing speeds required.  Rendering so much data is of course akin to rocket science. For images with resolutions 50 times greater than produced before, data will have to flow incredibly fast.  But the volumes of data are so massive that local and international technicians are still hard at work trying to build them.  

The ROACH 2 is part of the SKA’s answer to the processing power needed, and the CSIR’s Centre for High Performance Computing (a vault of water-cooled 2 metre tall processors) tucked in sleepy Rosebank, Cape Town, is performing an important role in prototyping the SKA’s computer hardware infrastructure.

Carnarvon is already showing the benefits of all this activity – a bevy of guesthouses and eateries have sprung up, including De Meerkat, a wonderful new restaurant. 

On the site itself in the Northern Cape, massive construction is underway, including 64 circular platforms for the MeerKat array ( a total of 3000 dishes will be operational eventually, around the world), roads, and an underground bunker where signals will be processed. Signal processors will be buried 5 metres below ground, and shielded by a massive mound of sand around the facility, besides the shielding provided by the ring of mountains that guards the area.
In December this year the first of the new array of 64 antennas will be erected.The total project cost is estimated at €1.5 billion.

Scary Facts About the SKA:
The SKA central computer will have the processing power of about one hundred million PCs.
The dishes of the SKA will produce 10 times the global internet traffic.
The SKA will generate enough raw data to fill 15 million 64 GB iPods every day!
The SKA supercomputer will perform 1018 operations per second – equivalent to the number of stars in three million Milky Way galaxies – in order to process all the data that the SKA will produce.

The SKA will be so sensitive that it will be able to detect an airport radar on a planet 50 light years away.

The SKA will contain thousands of antennas with a combined collecting area of about one square kilometre (that’s 1 000 000 square metres!).
The SKA project timeline
Detailed design and pre-construction phase
Phase 1 construction
Phase 2 construction
Full science operations with Phase 1
Full science operations with Phase 2

What is Interferometry ? How does the SKA work?

An interferometer’s main purpose is to increase the resolution of images using aperture synthesis.  By overlaying waves, those that reinforce one another (or are similar) are enhanced, whilst those of opposite phases cancel one another out.  The result is a much sharper image, and beyond the image itself is plenty of information beyond the visual, such as heat energy signatures, radiation, dark matter elements such as time, movement and gravity that can be measured. An array amounts to a combined telescope that approximates a single telescope, but is simply super-sensitive in what it can see.The baseline determines the resolution, and some systems span continents – which are known as VLBI or Very long Baseline Interferometry.

 READ MORE: Once upon a starry night: The story (so far) of the Square Kilometre Array

Corporate Photography - Freightliner