The green light to build the world’s largest radio telescope

The telescope – which is being built partly in South Africa and partly in Australia – will soon consist of nearly 200 dishes and more than 130,000 antennas.

After years of preparation – much thought has been given to what the final radio telescope should look like and the necessary technologies have already been tested and developed – the decision was made last week. Construction is underway square kilometer array (In short: SKA): The largest radio telescope on Earth.

cheer
The decision sent radio astronomers into a jubilant mood. So is Professor Philip Diamond, General Director of Square Kilometer Matrix Organization (SKAO), he couldn’t believe his luck. “I’m in ecstasy. We’ve been working for this moment for 30 years. And today an important step has been taken (…) to build not one, but two of the largest and most complex networks of radio telescopes here on Earth, designed to reveal some of the universe’s most amazing secrets. The news was also cheered in the Netherlands (one of the SKAO member countries, see box). “We are very pleased with the news that the construction of SKA has finally begun,” said Michael van Haarlem, head of the Dutch SKA office.

The Square Kilometer Array is an intergovernmental project that 16 countries – including the Netherlands – have been working on for years. Countries will pay for and build the radio telescope together. The Netherlands is investing about 30 million in SKA and will also supply various components. It is being built by ASTRON, the Dutch Institute for Radio Astronomy.

Bigger and more sensitive
There are of course quite a few radio telescopes available around the world. Van Harlem explains that the square kilometer matrix is ​​clearly different from this Scientias. nl. “SKA is larger and therefore more sensitive than current instruments and thus can look deeper into the universe (and go back in time).”

The huge radio telescope consists of two parts. One part rises in South Africa and consists of 131,072 antennas. The other part will be in Australia and contain 197 radio dishes. Antennas and dishes pick up radio waves, which are then converted into digital signals that are further processed in ultra-fast computers. The end result, for example, is images of the sky at radio wavelengths and other processed signals that can be used to study stars and planets.”

Interferometers
The two telescopes located in Australia and South Africa operate separately from each other. “One (in Australia) on the longest wavelengths and one in South Africa on somewhat shorter wavelengths,” van Harlem says. “Both are examples of interferometers.” This means that observations made simultaneously by thousands of antennas in South Africa are combined. The same goes for the reviews of nearly 200 dishes in Australia. This actually simulates a huge radio telescope with a total receiving area of ​​approximately 1 square kilometer.

Expectations
Expectations are high, as it turns out when we asked Van Haarlem what SKA could reveal. “SKA is a widely applicable tool with which many investigations can be carried out. From studying the first stars and galaxies in the early universe, to mapping the distribution of hydrogen gas in near and far galaxies, to searching for pulsars (the remnants of ancient stars that emit pulsations) of radio radiation). Too much to mention.”

The location of the antennas (it can be seen in this artistic impression) and the dishes is well thought out. A conscious decision was made for the hinterland of Australia and South Africa. “Far from the interference signals that humans generate,” van Harlem says. “Elsewhere on Earth, human activity hampers the most sensitive observations.” Photo: SKAO/ICRAR.

patience
Radio astronomers are eager to check out the first images from the Square Kilometer Array, but some patience is required. Although it has been officially decided to start construction, it will take some time before the spade enters the earth. It is expected that there will only be some activity in selected locations in Australia and South Africa at the beginning of 2022. In the lead up to this, member states were not sitting idly by; They will prepare to build their parts. “In the coming months, Dutch companies will receive orders to supply the necessary software and hardware for them square kilometer array It will be completed by the end of this decade,” says Van Harlem.

first scenes
As it looks now, it is square kilometer array In the year 2028. Fortunately, the first observations did not take long. “A telescope like SKA is built in stages. Observations can begin before all the antennas and dishes are placed. We expect the first results from 2024.”

The value of the construction and use of the largest radio telescope in the world is about 2 billion euros. “It’s a lot of money, which is why 16 countries are working together to build this telescope. We share the costs, so we get access to a telescope that is more sensitive than each country can afford on its own,” explains Van Harlem. “And the technological innovation required to build such a complex tool creates opportunities for companies in the participating countries.” But radio astronomers’ heart beats faster at the idea of ​​SKA because of fundamental questions that a powerful radio telescope can help answer. Ex: How are stars and galaxies formed? What will happen to the universe in the distant future? Is there intelligent life elsewhere on other planets? These are all questions that astronomy, and therefore also SKA, wants to answer.”