Mersen technology for the most powerful telescope in the world

Paris, March 11, 2019 – Mersen (Euronext FR0000039620 – MRN), a global expert in electrical power and advanced materials, has announced that it will be taking part in the Extremely Large Telescope (ELT) project run by the European Southern Observatory (ESO), helping to complete the fifth and final mirror for this giant future telescope, which is the most powerful in the world.

Mersen had previously been tasked with creating the reference structure for the fourth mirror by the Italian consortium AdOptica. This time, the company in charge of the project, Safran Reosc, chose Mersen for its silicon carbide (SiC) based solution.

The Group’s subsidiary Mersen Boostec will manufacture the reduced-weight mirror blank from SiC, matching Safran Reosc’s specifications. SiC is a lightweight, stiff, stable ceramic that is very little sensitive to temperature fluctuations, and is a popular choice for optical instruments due to its unrivaled thermo‑elastic stability.

Mersen Boostec is well-known for its silicon carbide expertise, having equipped more than 19 all‑SiC telescopes that are already in orbit, and this order is a direct result of that expertise.

Mersen has been contributing to astronomy for the past 20 years, working on prestigious ESA space missions as Rosetta, Herschel and GAIA, and will soon take part in NASA’s JWST mission. The ELT project is a major ground-based astronomy project for the Group. 

About the ELT

The ELT is a huge telescope whose primary mirror spans 39m in diameter. It will allow significant progress to be made in astronomy (stellar archeology, exoplanet discovery and categorization, etc.)

About Safran Reosc

Safran Reosc is a subsidiary of Safran Electronics and Defense, Safran’s high-tech company and is a world leader in high-performance optic design, production and integration for the astronomy, space, high-powered laser and semiconductor industries in the civil and defense sectors.

About the ESO

The ESO is an intergovernmental astronomy organization founded in 1962 by five European countries, in order to provide astronomers with a state-of-the-art, ground-based astronomical observatory in the Southern hemisphere.


About Mersen

A global expert in electrical power and advanced materials, Mersen designs innovative solutions to address its clients' specific needs to enable them to optimize their manufacturing performance in sectors such as energy, electronics, transportation, chemicals & pharmaceuticals and process industries.

Mersen, with 6,900 employees working across 35 countries, recorded sales of €879 million in 2018.

Mersen is listed on Euronext Paris – Compartment B


Véronique Boca
VP, Communication Mersen
Tel. + 33 (0)1 46 91 54 40

FTI Consulting Strategic Communications
Stanislas Mulliez/Guillaume Granier
Tel. +33 (0)1 47 03 68 10
Email: /


Photo: © ESO (

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Mersen: taking part in the Extremely Large Telescope project