Disused Sardinian mine proposed as location for underground telescope

The Einstein Telescope is a proposed underground infrastructure to host a third-generation, gravitational-wave observatory

Albert Einstein predicted gravitational waves in 1916 on the basis of his general theory of relativity as ripples in spacetime. The telescope is expected to capture the waves and observe a volume of the universe much larger than is seen by the tools currently used, known as interferometers.

The new telescope will build on current laser-interferometric detectors such as Advanced Virgo and Advanced LIGO, whose breakthrough discoveries of merging black holes and neutron stars over the past five years have ushered scientists into the new era of gravitational-wave astronomy. 

It will achieve a greatly improved sensitivity by increasing the size of the interferometer from the 3km arm length of the Virgo detector to 10km, and by implementing a series of new technologies. These include a cryogenic system to cool some of the main optics and new quantum technologies to reduce light fluctuations.

An old lead and zinc mine, which lies 300 metres underground, has been proposed by the Italian government as the location for the new device.

Nobel Prize winner Giorgio Parisi is leading Italy’s bid to host the Einstein Telescope, which will be an EU-financed project.

Alongside other scientists, he has said that the mine is in an ideal location due to the area’s low seismic activity and the absence of settlements nearby. The final decision will be announced by the end of next year, but Italy faces a rival bid from a site in Meuse-Rhine, a region divided among the Netherlands, Germany and Belgium. Italy hopes that the €1.9bn project will bring much-needed investment to Sardinia, which is one of the country’s poorest regions.

Although still in the early design study phase, the basic parameters of the Einstein Telescope are established. A prototype, or testing facility, called the ETpathfinder was built at Maastricht University’s Randwyck Campus in the Netherlands and opened in 2021.

Regardless of where it is located, construction on the telescope is expected to begin in 2026 with the goal to start observations in 2035.

Last December, building works started in South Africa and Australia to build the Square Kilometre Array, which is set to become the largest radio telescope in the world.