Athermalization of space instruments with mechanical metamaterials: structural instrument architectures and conceptual design of an in-orbit demonstration experiment

Abstract Space instruments are nowadays inevitable for astronomy and Earth observation. Designing and building them remain a costly and challenging engineering task as they are exposed to harsh environmental conditions in space and during transfer to orbit. In particular, the induced thermal deformations into the instrument structure must be mitigated in order to ensure optimal instrument performance which is called athermalization. Current research addresses this challenge primarily through the application of advanced shape control systems as well as sophisticated materials and manufacturing methods. With the advent of metallic multi-material additive manufacturing, the production of advanced materials such as thermoelastic metamaterials becomes feasible for space applications. These materials are lattice structures with tunable coefficient of thermal expansion (CTE), including both negative and zero CTE, and high stiffness. Furthermore, the controlled heating of these metamaterials allows for the design of thermoelastic structures with advanced shape control. They are therefore well-suited for thermostable space instrument structures which is addressed only rarely in research. This work presents the derivation of principle space instrument architectures with athermalization through the utilization of thermoelastic metamaterials. In this course, architectures with and without shape control are considered. The required steps for implementing this technology are presented according to a Technology Readiness Level (TRL) classification. Finally, a suitable in-orbit demonstration experiment is presented, namely the Modern Structures Experiment of the SeRANIS mission.