Thin aperture light collector (TALC) is the next generation of telescopes for space exploration. TALC consists of deployable annular segmented mirrors supported on a central mast with the help of cables. The dynamic stability of the telescope is of immense importance in order to make sure that the telescope is pointing in the right direction during the observation period. We present a control strategy for the dynamic stabilization of the segmented TALC structure using active rods. The active rods consist of collocated pairs of piezoelectric stack actuators and sensors. Decentralized integral force feedback is proposed to enhance the dynamic stability of the TALC. The effectiveness of the strategy is demonstrated on a 1/10th scaled mock-up model of the TALC. For numerical investigation, finite element analysis of the TALC is carried out and a reduced order model is extracted using the Craig–Bampton method. This reduced order model is then used for the design and numerical validation of the controller. Experiments are conducted on the mock-up model of the TALC to evaluate the performance of the proposed strategy. It is found that the proposed strategy is quite effective for dynamic stabilization of TALC. It is found to reduce both steady state and transient responses of the TALC.
Astronomy is driven by the quest for higher sensitivity and improved angular resolution in order to detect fainter or smaller objects. The far-infrared to submillimeter domain is a unique probe of the cold and obscured Universe, harboring for instance the precious signatures of key elements such as water. Space observations are mandatory given the blocking effect of our atmosphere. However the methods we have relied on so far to develop increasingly larger telescopes are now reaching a hard limit, with the JWST illustrating this in more than one way (e.g. it will be launched by one of the most powerful rocket, it requires the largest existing facility on Earth to be qualified). With the Thinned Aperture Light Collector (TALC) project, a concept of a deployable 20 m annular telescope, we propose to break out of this deadlock by developing novel technologies for space telescopes, which are disruptive in three aspects:
• An innovative deployable mirror whose topology, based on stacking rather than folding, leads to an optimum ratio of collecting area over volume, and creates a telescope with an eight times larger collecting area and three times higher angular resolution compared to JWST from the same pre-deployed volume;
• An ultra-light weight segmented primary mirror, based on electrodeposited Nickel, Composite and Honeycomb stacks, built with a replica process to control costs and mitigate the industrial risks;
• An active optics control layer based on piezo-electric layers incorporated into the mirror rear shell allowing control of the shape by internal stress rather than by reaction on a structure.
We present in this paper the roadmap we have built to bring these three disruptive technologies to technology readiness level 3. We will achieve this goal through design and realization of representative elements: segments of mirrors for optical quality verification, active optics implemented on representative mirror stacks to characterize the shape correction capabilities, and mechanical models for validation of the deployment concept. Accompanying these developments, a strong system activity will ensure that the ultimate goal of having an integrated system can be met, especially in terms of (a) scalability toward a larger structure, and (b) verification philosophy.