At a historic meeting of its Council on 25 June 2021, the SKA Observatory (SKAO) saw its Member States give the green light for construction of the SKA telescopes in Australia and South Africa to commence. We spoke to Michiel van Haarlem, head of the Dutch SKA Office at ASTRON, about what this important milestone means.
Published by the editorial team, 29 June 2021
What is it like to be involved in such an immense project?
“Impressive. It is varied because I see a lot of SKA: astronomy, technology, but also the organisation that is needed to steer such a project in the right direction. And also, the political and cultural dimensions of global cooperation. This is the first time that radio astronomy has cooperated in such an intense way. Synchronising the plans in all the participating countries is quite a challenge. The added value, of course, is that together we can build a telescope that is much more sensitive than the countries could afford separately.”
What does the tendering phase of SKA entail and what kind of opportunities does it offer for researchers and companies? How will the Netherlands benefit?
“I would rather call it the construction phase of SKA, because that is what deserves emphasis. Tendering is an important step, but that is only a small part of the work in the coming years. During the negotiations between the SKA member states, the countries agreed on how to divide much of the construction work. It comes down to the fact that countries mainly focus on building those parts of SKA where they also contributed to the design in recent years. For the Netherlands this means we are due to take on work in the following areas:
- software for the calibration of data and the creation of deep sky images,
- the construction of the correlator/beamformer of SKA-Low - this is the "supercomputer" that gathers the data from the antenna stations and processes it at high speed.
- electronics and photonics/lasers with which the signals from SKA-Low's antennas are transported over tens of kilometres (this step means that less hardware is placed in the field, which also helps us to minimise the amount of interference we generate ourselves).
Dutch companies are ready to make an important contribution to this, together with ASTRON. The contracts are due to follow in the next 18 months.”
What will SKA mean for astronomy? And how does SKA compare to LOFAR?
“SKA will play an important role in many areas. The beauty of it is that it is a telescope that operates over a wide range in frequency and resolution (image sharpness) and will therefore have an impact on many areas of astronomy (from mapping the first stars/star systems in the early universe to the study of pulsars and planets).
Although SKA is much more sensitive than LOFAR, that telescope will still be very important for at least the next 10-20 years, for the following reasons: LOFAR has a much higher image sharpness - this is because its antenna stations are spread over a much larger area (LOFAR: thousands of km; SKA: ca. 100 km). Also, LOFAR sees mainly the northern sky, while SKA is in the southern hemisphere and therefore sees the southern sky. In that respect they complement each other well.”
The cost estimate of building the SKA is 1.9 billion euros from 2021-2030. How will the money be spent and how much will the Netherlands contribute?
“The division is about 50:50 between construction costs (antennas, dishes, receivers, correlators, (super) computers, software, networks and also their construction + infrastructure (roads, buildings) and operational costs (personnel, energy and network costs). The Dutch contribution is about 39 million over a period of 10 years. This contribution comes from the Ministry of Education, Culture and Science and from ASTRON.”
When will the construction of SKA start and when are the first observations expected?
“The start will be early next year (infrastructure construction). Until then, we are busy starting the construction work, awarding contracts etc. The first preliminary results are expected in 2024. Around that time, we will have built less than 10% of the final telescope. In the years that follow, construction will be completed and the telescopes will be more and more sensitive. The South African MeerKAT telescope will be incorporated into SKA, but this transfer will only take place in about 2028, at the end of the construction phase. Until then, MeerKAT will continue to function as an independent instrument.”
The two telescope sites each get a different focus: low-frequency in Australia, mid- and high-frequency in South Africa. Will they function as one telescope?
“The two telescopes, SKA-Low and SKA-Mid, will operate independently. They will have separate receivers operating at different wavelengths/frequencies. There will be no long baseline observations where antennas in the two countries meet. Although simultaneous observation of the same source in the sky is possible in itself, they will usually make separate observations. This also means that two different observing programs can be carried out simultaneously.”
How much data will SKA produce and how will it be processed?
“SKA will produce enormous amounts of data - up to 1 Exabyte per year. The data comes from the telescopes in Australia and South Africa and is distributed over a network of SKA Regional Centres for archiving and further processing, analysis and eventually publication. The Netherlands will also have such a Regional Centre. Astronomers will only be able to access their SKA data at these Regional Centres. Apart from building SKA, teams from the Member States will work hard in the coming years to develop and build the software and hardware to extract scientific results from the vast SKA data stream. The Netherlands’ contribution to development of the Regional Centres will build on ASTRON’s Science Data Centre efforts in close collaboration with the Dutch astronomical community.”