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It takes two (or more) to build a telescope

How do stars and galaxies form? What is dark matter? To answer these and other questions, we need increasingly large telescopes. And to build these, we need international partnerships. A series on the impact of collaboration.

‘Theoretical models will get you some of the way, but you always need observations from telescopes and satellites,’ says Huub Röttgering, Professor of Observational Cosmology and Director of Leiden Observatory. ‘As an institute or university, you’re much too small to build a big telescope or launch a satellite. These are projects that cost hundreds of millions to a few billion.’ To make such projects possible, large European or even global partnerships are formed.


These partnerships have a certain structure. Satellite construction is led at the European level by the European Space Agency (ESA). ‘They ensure that a telescope is installed or a rocket built that can launch a satellite,’ says Röttgering. Then there are the institutes, such as the Netherlands Institute for Space Research (SRON), which build instruments used to collect data. SRON, which is part of the Dutch Research Council (NWO), makes cameras, for example, that record X-rays or infrared radiation in space.

As an institute or university, you’re much too small to build a big telescope or launch a satellite

Researchers at universities use the data collected by these instruments to test theories and answer research questions. But they are involved at a much earlier stage of projects.

The first step could entail we researchers discussing which data we need for the next step of our research with the engineers at SRON,’ says Röttgering. ‘Then it’s a case of looking with the instrument and satellite builders at what is technically feasible and relatively affordable. If ESA agrees – and this only happens with a few projects – we as a collective look for funding, and construction can begin.’

Quasar with X-rays

In 1999, ESA launched the XMM-Newton satellite with an SRON instrument on board that can measure X-ray light. This was used to look at a quasar four billion light-years away. Quasars are large galaxies with a supermassive black hole in the centre that emits X-rays. The data collected enabled researchers from SRON and the Leiden Observatory to determine the composition and mass of interstellar gas between the earth and the quasar.

‘SRON’s move to Leiden will make collaboration easier and as a result more intensive’

At present, SRON and Leiden University are working with various other international institutes on the Athena European space telescope. ‘Companies such as Airbus, or in this case Dutch company Cosine, are often also involved in these kinds of project,’ says Röttgering.

SRON is still based in Utrecht, but will move to the Leiden University science campus in 2021. ‘This will make collaboration easier and more intensive,’ says Röttgering. It will be much more simple to involve students, for instance from the Leiden master’s specialisation in Astronomy and Instrumentation, in the construction of measuring instruments.

Text: Dorine Schenk
Photo: The Old Observatory in Leiden
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