First segments of the world’s largest telescope mirror shipped to Chile

The development of the European Southern Observatory’s Extraordinarily Giant Telescope (ESO’s ELT) has reached an necessary milestone with the supply to ESO and cargo to Chile of the primary 18 segments of the telescope’s most important mirror (M1). As soon as they arrive in Chile, the segments will probably be transported to the ELT Technical Facility at ESO’s Paranal Observatory within the nation’s Atacama Desert, the place they are going to be coated in preparation for his or her future set up on the telescope’s most important construction.

Unable to be bodily made in a single piece, M1 will encompass 798 particular person segments organized in a big hexagonal sample, with an extra 133 being produced to facilitate the recoating of segments. With a diameter of greater than 39 meters, it is going to be the biggest telescope mirror on the planet.

The ultimate stage within the production process of M1 segments—sharpening—was carried out by world-leading optical programs producer Safran Reosc close to Poitiers, central France, at a constructing utterly refurbished to work on this delicate job. As a part of the method, Safran Reosc developed new automation workflows and measurement methods to make sure that the sharpening met the high standards required for ESO’s ELT.

The floor irregularities of the mirror are lower than 10 nanometers (lower than one-thousandth of the width of a human hair). To succeed in this stage of efficiency, Safran Reosc used a way referred to as ion-beam figuring, wherein a beam of ions sweeps the mirror floor and removes irregularities atom by atom.

Whereas solely 18 segments have been shipped to this point, many extra will quickly be delivered by Safran Reosc to ESO. On 1 November 2023, the one centesimal section went out of the production line and entered into the intensive inspection phase that takes place earlier than last supply.

Moreover, Safran Reosc has achieved a manufacturing charge in extra of 4 segments per week, with a goal of 5 per week anticipated quickly, a exceptional achievement for the collection manufacturing of extremely high-accuracy optics.

The development of ESO’s ELT has required the shut involvement of a number of corporations in Europe and Chile with ESO’s groups, highlighting how the telescope is a really worldwide endeavor.

The mirror segments have been forged by the German firm SCHOTT at their facility in Mainz, Germany, earlier than being delivered to Safran Reosc in France for sharpening. Different corporations concerned within the work accomplished on the section assemblies embrace Dutch firm VDL ETG Tasks BV who produced the fragile section helps; German-French FAMES consortium who developed and manufactured the 4500 nanometric-accuracy sensors monitoring the relative place of every section; and German firm Physik Instrumente who designed and manufactured the 2500 actuators in a position to place the section to nanometric precision.

The fragile job of transporting the segments was assigned to Danish firm DSV.

Having left France final week, the 18 polished mirror segments at the moment are on their journey of over 10,000 km to the ELT’s development website within the Atacama Desert. From there, ESO’s ELT will deal with the most important astronomical challenges of our time and make but unimaginable discoveries as soon as it begins working later this decade.