# Design Analysis of a Passive Buffer System for Space-Assembled Segmented Mirrors
## 1 Introduction  
With the continuous advancement of human exploration of the universe, the demand for higher optical resolution has driven the aerospace observatory moving forward to the larger aperture ultraviolet-optical-infrared (UVOIR) space telescopes, with the primary mirror (PM) segmented [1, 2]. The prospective space assembled telescope [3, 4, 5, 6] will enable optical elements to be launched in batches, compared with traditional space optical telescopes employing monolithic optics [7]. Therefore, future space observation systems will overcome the launching mass and volume limitations. However, a critical issue is effectively capturing and connecting the precise optical mirror segments in space to determine the optical stability of the telescope structure [8].  
The connection technology applied between primary mirror assemblies (PMAs) means that two or more modular units are connected rigidly by locking mechanisms, with special docking interfaces to form the core of the synthetic aperture. Then, the co-focal and co-phase adjustment operations are executed with actuators attached to the backside of the individual mirror segments, thereby directly contributing to the optical performance. The space probe-cone docking mechanism is ideally suitable for the space small-scale cooperative target self-assembly tasks, mainly due to the high reliability of capture, high docking precision, and very compact structure. Because of the microgravity environment in space, a strong coupling effect exists between free-floating space objects in the docking process. Therefore, a buffer system is essential to alleviating the influence of the docking impact and controlling the contact force. However, considering the size compactness and power efficiency, it is difficult for complex active buffer systems to join this type of docking mechanism. In other words, if there is a simple solution to mitigate the impact coupling effectively during the assembly period, the probability for assembling PMAs on orbit will be greatly improved.  
At present, many organizations [9; 10; 11; 12] are conducting research on connection technology using space small-scale targets. The autonomous micro-satellite docking system (AMDS) [13; 14], developed by the Orbital Express (OE) project, utilized soft-docking technology [15] to buffer the impact. However, the docking conditions of this technology were harsh, undermining the overall capture rate. The Engineering Test Satellite VII (ETS-VII) [16] demonstrated autonomous rendezvous and docking experiments in space. The universal docking port (UDP), developed by the Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) team [17], adopted the electromagnetic techniques [18; 19] for active buffering. Its operation was difficult and energy consumption could not be ignored.  
In this paper, a novel design methodology named \"double-elastic contact model,\" is mainly developed for the passive buffer system between the modular PMAs to assemble one large-scale apertures. A connection mechanism called the Self-configurable Modular Adjustable Latch Lock (SMALL) is provided, using the passive buffer system to mitigate the impact. Through the universal explicit probe-cone interface, this simple and compact design contributes immensely to segmented mirrors to function monolithically. This paper is organized as follows. Section 2 analyzes the general capture process of the autonomous probe-cone docking mechanism for modular assembled mirror segments. And the \"double-elastic contact model\" is investigated in detail. In Section 3, a passive buffer system applied to the connection mechanism SMALL is implemented and analyzed to verify the theory mentioned in Section 2. Section 5 concludes our statements.