Cosmos
Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.
By Cosmos
The first 18 segments of the world’s largest telescope are en route to Chile in preparation for what will be one of astronomy’s biggest constructions on record.
Once complete, the European Southern Observatory’s Extremely Large Telescope (yes, that’s what it’s called) will be the biggest optical and near-infrared ground-based telescope. The project has been in development for nearly 20 years, with construction approved a decade ago.
It is due to come online in 2028.
The assembly of the telescope’s massive mirrors will take place over the next 4 years. This week, the first segments of what will be the main mirror – called ‘M1’ – arrived in Chile.
In total, M1 will consist of 798 mirrors assembled into an almost 40-metre-wide lens.
Before their arrival, these smaller mirrors had their imperfections atomically polished out by French optical systems manufacturer Safran Reosc by ‘sweeping’ their surface with a beam of ions that eat away at the irregularities. Any remnant flaws are no more than 10 nanometres wide – about the size of a biological cell membrane.
The remaining 780 pieces of M1 will be polished and shipped in the coming months, around 4 segments are being prepared each week by Safran Reosc.
The Extremely Large Telescope will be built in the Atacama Desert in the north of Chile, which is one of the darkest skies in the world.
