Square Kilometre Array radio telescope infrastructure rolls out


South Africa is rolling out infrastructure for the MeerKAT radio telescope, which is the prototype for the Square Kilometre Array radio telescope the country is competing against Australia to host from 2016.

SKA South Africa (SKA SA) is responsible for South Africa’s bid to host the €1.5 billion international Square Kilometre Array radio telescope, which will become fully operational by 2024. Australia and South Africa are the two countries shortlisted as hosts for the instrument. The SKA will be the world’s largest radio telescope and aims to shed light on how galaxies, stars and planets came into being.

South Africa’s chosen site is near Carnarvon in the Northern Cape, a desolate area that has few cellphone or radio towers to create interference. The SKA SA team is currently putting together a report on radio interference at the proposed SKA site, which will be one of the last submissions to the international SKA committee. Another required test will be conducted on the troposphere. The reports are due on May 31. The international SKA committee is expected to make its final decision as to which country will host the array in March next year. Construction work will begin in 2013 and operations will start in 2015. The winning country will earn around €200 million a year for 20 to 30 years in expenses related to operations and maintenance.

As part of the bid, SKA SA is designing and building the MeerKAT radio telescope, which is being partly funded by the Department of Science and Technology. MeerKAT will be one of the largest and most powerful radio telescopes in the world. Infrastructure for this device is being rolled out this year and should be in place by the end of next year. Infrastructure includes buildings, roads, the power supply, antenna foundations and the optical fibre network.

This month the User Requirement Specification Review will be undertaken for the MeerKAT, followed by the Preliminary Design Review of the technical specifications for the telescope in June. After that the MeerKAT design will be frozen.

A MeerKAT prototype has been built at the Radio Astronomy Reserve in the Karoo. Called the MeerKAT Precursor Array (MPA), the radio telescope is in the process of being commissioned. Construction of the MPA began in August 2009 and was completed in January last year. It comprises of seven composite parabolic dishes, each with a diameter of 12 metres. At a later stage it is intended to integrate the MPA with MeerKAT, which will comprise 80 dishes. MeerKAT should be completed by December next year and commissioned in 2013 at a cost of R860 million.

SKA SA is continuing its materials qualification programme, which has been running for the last year and aims to confirm that composite materials are suitable for radio telescope dishes of the size of MeerKAT. Using lightweight composites would allow manufacture on site, which would reduce costs and allow faster construction.

Some of the infrastructure for MeerKAT is already being tested. The new 33 kV power line connecting the MPA (previously KAT-7/Karoo Array Telescope) site at Klerefontein in the Great Karoo was switched on at the end of September last year.

The KAT-7 telescope is powered by a 22 kV line but this will be switched over to 33 kV once the upgrade to the Karoo substation has been completed in March next year. Back-up power is also provided to the radio telescope and buildings on site and at Klerefontein for use in the case of an Eskom outage.

The interim 10 Mbps data link between the SKA SA office (in Pinelands) in Cape Town and the KAT-7/MeerKAT site went live for the first time on 19 January. The link was commissioned by the South African National Research Network (SANReN) on behalf of the SKA SA project, and will be managed by Tenet.

The operation of KAT-7 can now take place from the SKA SA headquarters in Cape Town. This will reduce the engineering and commissioning team’s travelling time from Cape Town to the Karoo considerably.

Ultimately, MeerKAT and the Southern African Large Telescope (SALT) will be connected by a 10 Gbps data link, which will be completed by the end of June. The shared 10 Gbps link will cater for the full MeerKAT bandwidth requirements in future. The idea is that the SKA site will be linked to a powerful computer system in Cape Town.

However, Bernie Fanaroff, the director behind South Africa’s bid to host the telescope, says the country’s bandwidth situation is a challenge. “Very large bandwidth is required for the SKA. We’re talking about hundreds of terabits per second. That’s more than SA’s entire traffic. It’s more than America’s entire traffic.”

Fanaroff says SKA SA is in discussions with operators to address the problem. “If bandwidth costs here are going to be more expensive than in Australia, that’s going to make a difference. It’s going to be an important number.” However, he said he was confident South Africa will be cheaper than Australia in capital and construction costs – the only concern is bandwidth costs.

In 2012 the West Africa Cable System and Africa Coast to Europe cables will arrive, providing sufficient international capacity to meet the telescope’s requirements, even after taking into the Internet needs of South Africa’s population. South Africa went from 80 GBps in 2009 to 5 460 GBps early this year and will reach 15.7 TBps in 2012.

Even though construction of MeerKAT is only beginning, many astronomers have applied to use the telescope. Fanaroff said that more than 43 000 hours (five years) of observation time has already been allocated to astronomers. MeerKAT will be used to hunt for gravity waves, which have never before been detected but which theoretically exist. Scientists will look for distortions gravity waves would cause to faint radio signals emitted by pulsars (dense remains of exploded supernovae).

The Minister of Science and Technology, Naledi Pandor, said: “This demonstrates South Africa’s commitment to ensuring that the SKA becomes a major catalyst for scientific development in Africa”. The SKA initiative is in line with the Government’s Astronomy Geographic Advantage Programme (AGAP), which aims to establish a hub of world-class astronomy facilities in Southern Africa.

The Square Kilometre Array was born in the early 1990s when astronomers decided they would like to be able to observe hydrogen from the birth of stars a few hundred million years after the Big Bang. They were looking for ‘neutral’ hydrogen (a single proton orbited by a single electron) which is found in the vicinity of stars that are being born. To do this would require a giant radio telescope with an area of at least one square kilometre.

South Africa became involved in the project in 2005 when it asked to become one of the countries bidding to host the telescope alongside the United States, China, Canada, Argentina and Australia. In 2009 cabinet approved a R1.6 billion budget to win the right to host the instrument. The budget includes construction of the MPA and MeerKAT. If South Africa wins the bid, other southern African countries in a 3 000 km radius will host outlying stations that connect to the main Karoo site. Namibia would host about three antenna stations; Botswana four; and one each in Mozambique, Mauritius, Madagascar, Ghana, Kenya and Zambia. Each antenna station will consist of roughly 30 to 40 antennae.