The status of the contract for the preliminary design of the EST M1 assembly is presented
The EST M1 Assembly contract, carried out by SENER, is ongoing. In the last months, the Phase 2 has been satisfactorily finished and we are currently immersed in Phase 3. In parallel, the design of the prototypes was finished and they are currently in production.
During Phase 2, the baseline design adopted for the M1 Assembly was fully developed. The design was analysed in detail and improved in order to ensure the accomplishment of all requirements in the most efficient way.
The axial actuators concept was developed up to a detailed design level. Two options for the drives and gears were proposed, and they will be carefully tested during the prototype test campaign. The concept of the lateral actuators (initially proposed aligned with the Y-axis) was changed to a tangential distribution, which improves mirror safety during manipulation, allows some degree of XY displacement, and reduces thermal effects over the M1 mirror.
Exploded view of the EST M1 Assembly. Credit: SENER Aerospatial
The thermal control system was also fully developed. A detailed analysis with a full CFD model was performed in order to ensure that both M1 mirror and cell temperatures fall inside requirements. Apart from that, the most critical updates in design were the inclusion of an external cover that allows passive cooling of the cell and detailed analysis of the fan-induced vibrations.
Concerning the thermal control and the axial actuator prototypes, the design and test plans documentation was finished and approved by the EST Project Office during the first quarter of 2022. The prototypes are currently in production. It is expected that they will be ready for testing during July 2022, when some members of the EST PO will visit SENER near Barcelona (Spain), to check the prototypes and to be present when the most critical tests are carried out. Apart from other minor topics, these tests will address three critical issues: performance of the axial actuators, thermal control of the mirror, and vibrations generated by the fans. The results obtained from the tests will be used to update the M1 Assembly design (if required). Unfortunately, the global situation during the last months, with COVID-19 and the Ukranian war, has made it difficult to procure some materials, which has resulted in delays.
We are currently immersed in Phase 3. During this phase, apart from updating the analysis and design with feedback from the prototype tests, also a new set of documentation is being produced and will be reviewed in the M1 Assembly specific PDR. The review will be conducted in mid-September 2022 and will define the end of the present contract. This documentation is the main output of the contract, and it has two main objectives: to ensure the technical, operational, and economic feasibility of the M1 Assembly and to establish the basis for launching the detailed design and construction tender.
The EST M1 Assembly will be present at the SPIE Astronomical Telescopes & Instrumentation 2022 conference with two oral contributions and the corresponding papers. The EST PO will deliver the talk “M1 Assembly for EST: selection of the most promising baseline configuration for the preliminary design”, where the trade-offs performed and the baseline design selected in Phase 1 will be described. On the other hand, SENER will present “The preliminary design of the M1 Assembly for the European Solar Telescope”, which will describe the M1 Assembly preliminary design and its main performance.