The most important place in the universe

Date:16 July 2018 Author: Brendon Petersen Tags:, , ,

Words by Lindsey Schutters

 

I almost blew up the most important astrophysics instrument in the world because I forgot to take my Fitbit off. I was told that a solitary dish can detect a cellphone on Pluto and that if there was intelligent life on a planet in the Andromeda galaxy – our nearest galactic neighbour, 2,5-million light years away – and they used our aviation equipment, MeerKAT could detect the radar signal. That level of sensitivity is amazing if you’re looking for life in the corners of the cosmos or tracing the origins of the known universe, but really terrible for tourists wanting to visit such a significant scientific site. Luckily my Fitbit can be turned off and the camera I use is too old to have Wi-Fi or Bluetooth radios.

And that’s half of the problem that the SKA and precursive MeerKAT projects face with regard to the Carnarvon community: locals can’t simply go out and see it to gain a deeper understanding and therefore don’t trust it. I quizzed the owner of the guesthouse my family and I stayed in (iKaia Africa Lodge) about her feelings and she bemoaned the fact that visitors always request tours of the facility. “I want to see it like you did,” she says.

The other part of the problem is isolated incidents of farmers who refuse to sell their land and then spread misinformation about the size and severity of the radio quiet zone. Granted, the project does actively try and limit radio frequency interference in an 80 km radius, but it cannot compel the public using the public road that the Department of Science and Technology paved (to the tune of R200 million ringing in the register) for traffic to the telescope site to not whip out their phones and take pictures.

The instrument is positioned on land that the DST owns, with a servitude from the Department of Agriculture. Owned land was bought from the farmers at market value, less drought deductions. Amazingly the deals were completed within a financial year.

It’s an unfortunate impasse and one that fuels the growing tension between community and researchers. There are four farms out of the 11 purchased so far within the 132 000 hectare area required for the SKA project where servitude agreements were struck. These farms, and the subsequent farms to benefit from the agreements, will be fitted with satellite-linked box phones and specially developed mobile phones and two-way radios. Farmers will also be equipped with spill-free Wi-Fi and benefit from the SKA telecommunications infrastructure.

By no means is there any denial of disruption to the local economy, but a project as significant as this that will exist in the area for at least half a century will require a bedding-in period.

Fortunately the MeerKAT phase of the project achieved final lift (positioning of the last dish) in November of 2017. Now we’ll see if all the fuss was worth it.

Our part of the square kilometre array is tasked with the 350 MHz to 14 GHz range of the cosmic spectrum.
So far there has been 1 300 galaxies observed during the first light images with only 16 antennas active and one super-massive black hole. MeerKAT also delivered crisp radio images of the Messier 83 galaxy (15 million light years away) – which was first discovered in Cape Town in 1752 – after a mere 50-minute exposure using 32 antennas. The obvious potential of the project is well documented, but the quality of execution is a thing of marvel.

The main building at the site is called the KPB (Karoo array Processing Building) and it is breathtaking. Think about it: all you need is a concrete box to house the computing power, timekeeping and electricity works. Instead the architect

delivered something special; a matrimony of form and function.

At its heart lies a maser hydrogen atomic clock, the central synchroniser for the digitisers on each antenna. The significance of the project forced the National Metrology Institute of South Africa (NMISA) to upgrade the national time reference by a factor of 1 000 from less than 5 000 nanoseconds to an instantaneous sub-4 ns. This accuracy is necessary to form clear images when using an array because the signals from each antenna reach the data processing centre at different times and then needs to be collated. Correlation and beam forming of the signals will allow the array to operate as one big receiver to arrive at a high-resolution image of the sky.

The instrument will be used to look further into space than ever before, identifying objects where time and space is distorted to reveal the birth of the universe.

A surprising thing about the KPB is that the entire building is a Faraday cage to help contain all the RF interference that could affect the instrument. Inside the building, apart from the aforementioned atomic clock, is a high-performance computer which is tasked with crunching the 4 GB per second of data coming off each antenna. With the site getting power from the local grid, a processing station needed to be fitted to smooth out the erratic spikes in the three-phase signal. There are also four diesel generators which can keep things going if power supply
is interrupted.

Talking about power supply, the poles carrying the cables into the site are purpose-built to reduce RF interference and the entire network is inspected twice a week, mainly to ensure that birds don’t nest – massive nest networks housing thousands of birds are a common problem in the Northern Cape.

The building is an ironic addition to an area that is said, and is evidenced by the shape of the mountains and fossilised crustaceans, to have been a shallow sea a couple of million years ago. The irony here being that intelligent life looking at us from the reverse vantage point that SKA will give us will see an entirely different landscape. Maybe they’ll plan some beachfront developments.

 

While the core MeerKAT site is the current hype machine, located within it is a project that will really put Carnarvon on the map. HERA (Hydrogen Epoch of Reionisation Array) is a radio telescope that is looking for the first stars in the universe. You’d never say it, though, because the meranti wood, PVC pool pipe and chicken mesh construction looks more like a garden project.

Materials were sourced locally, stimulating those sectors with around R6 million in purchases, and labour is also locally sourced. The project is earmarked for a Nobel prize and it’s currently competing in a flat-out race to first discovery between sites at SKA, SKA-low (Australia) and LOFAR (the Netherlands).

This array is a collaboration between South African, British and American institutes and is focused on detecting the red-shifted hydrogen power spectrum signature, indicative of the cosmic dawn. The end goal is a 3D map of the universe during the epoch of reionisation era, making HERA a single-purpose device as opposed to the multiple applications of MeerKAT and KAT-7. The antennas are immobile and the entire instrument is meant for low-frequency detection.

International stakeholders include the US National Science Foundation, University of Cambridge Cavendish Laboratory and the University of California at Berkeley. The precursor to the project called PAPER (Probing the Epoch of Reionisation) collected data for five years off 128 antennas on the site and the 331-antenna HERA array will increase the detection area by 30 times.

Much like KAT-7, HERA relies on remote digitising inside a container, with electronics running from the instrument into innovative bar fridges, which have been modified to house the data cables. Although these antennas are bigger than the precursor, individually it offers a smaller field of view. This is, however, offset by a greater sensitivity.

The container, which digitises the data, will be moved to a location just west of the current site and correlation will be done at the KAPB. This information will be invaluable in its informing of the projects happening at SKA and can be described as the most significant cosmological undertaking currently underway.

Powering all of this research is an incredible currently 7 GB per second fibre network and a fluid staff complement of scientists, engineers and operations technicians. While the project is touted as one of significant scientific significance, it is built on a bedrock of engineering sensibilities and sound principles. Our visit, for instance, coincided with the road scraping to make the gravel tracks smooth. Though there is a purpose-built road grader on site, there is no qualified driver. The engineers took matters into their own hands and dragged two truck tyres behind a bakkie to arrive at much the same conclusion.

That’s just one of many unique solutions that the staff have come up with. In the design of the MeerKAT antennas, the receivers can dip to within reach of an average-sized person. This reduces the need for specialised equipment to do routine maintenance. There’s even a small truck with an extended floor beyond the load area that serves as an elevated mobile workshop.

Because of the required radio silence, engineers on site have become exceedingly good at building ground level RF-shielding boxes. Everything is neatly packaged and will stand as a testament to the skills of the artisans tasked with construction work. All 64 19,5 m tall, 42-ton antennas are needed to stand up to the harsh Namaqualand environment for at least half a century. A big ask for an instrument that theoretically could explode when overwhelmed by my Fitbit’s Bluetooth signal.

At least 75 per cent of the MeerKAT array is sourced from South Africa; this places local industry leaders like Efficient Engineering, Titanus Slew Rings and Tricom Structures shoulder to shoulder with international suppliers such as Vertex Antennentechnik, General Dynamics and Oxford Cryogenics. The latter company is tasked with keeping all the antenna electronics and signalling infrastructure cooled to absolute zero in the sweltering Northern Cape sun.

When completed, SKA will be the premier L-Band (0,9-1,67 GHz) radio telescope in the world and the most sensitive radio telescope in the southern hemisphere.

To date, the project has trained 72 artisans at its Losberg FET facility 80 km outside of Carnarvon and there are 13 undergrad university students currently studying on SKA bursaries in South Africa. Carnarvon High School has been the centrepiece for STEM studies, with 105 bursaries handed out to students in the surrounding towns to attend the school and 11 teachers deployed. Pass rates and average science and maths marks have seen significant increases.

This doesn’t detract from the crushing poverty experienced in the town, augmented by the continued drought in the area. A brief stay in Carnarvon was met with a steady supply of beggars hanging around local shops and establishments. The week preceding the trip saw 22 mm of rainfall overnight on the surrounding farmlands, a brief respite for the sheep farmers who have been pushed to the brink, with many farms shuttering due to failing on loans.

These people don’t care about finding aliens or proving Einstein’s gravitational theory. In fact, many are more inclined to believe that the search into the heavens has enraged a deity who has cast down the drought as punishment for our inquisitiveness.

Leaving Carnarvon is bittersweet. The museum and its beautifully restored corbelled house had been closed for the weekend since 3 on Friday afternoon, so we didn’t get to see it. The SKA visitors’ centre was closed and needed the alarm repaired, a necessary evil to combat the scourge of break-ins. The public pool opposite our guesthouse showed no signs of ever having been in operation. The fuel station issued a hand-written receipt. Yet a mere 86 km down the road exists the most important window we have to the universe. Drought conditions make for perfect star-gazing.

First published in the March 2018 issue of Popular Mechanics SA.

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