# Development of a Novel Deployable Solar Panel and Mechanism for 6U CubeSat of STEP Cube Lab-II
## 1 Introduction
Recently, to overcome the above-mentioned technical issues, multiple HRMs or an HRM with an additional launch restraint mechanism has been applied to provide surplus mechanical fixation points on a solar panel to minimize dynamic deflections [12; 13]. For example, GomSpace [12] developed a multi-array deployable solar panel made up of aluminum (AL6082 T6-51) for application in 3U and 6U CubeSats, where two sleds with spring-based burn wire cutting HRMs were used to reduce the dynamic response of the panel under launch environments. The maximum power generation capacity from a single panel is 20.7 W. The mass of the GomSpace deployable solar panel module was 449 g. In addition, various configurations of mass-effective multi-array-based deployable solar panels made up of graphite have recently been proposed by MMA design LLC [13], in which an additional launch restraint system was implemented in conjunction with a burn wire cutting release mechanism. However, the implementation of multiple HRMs or an additional launch restraint device in a single panel could increase system complications, solar panel development costs, and minimize the accessible accommodation area for solar cells on the panel. Furthermore, HRMs based on a burn wire release technique have been widely utilized in deployable solar panels of CubeSats owing to their simplicity, relatively low cost, and ease of mechanism reset [14]. However, as the solar panel size is increasing to meet the increased power demands of forthcoming advanced space missions, the mechanical design of conventional wire cutting release mechanisms should be improved to ensure high holding capability and to guarantee secure reliable release action in an in-orbit environment. To overcome the aforementioned drawbacks of the current state-of-the-art mechanical design strategies for minimizing solar panel dynamic deflection, we focused on constrained layer damping by the implementation of multilayered thin stiffeners with double-sided viscoelastic tapes. The applications of viscoelastic materials for structural vibration control have been widely studied and practiced in space engineering fields owing to their simplicity and cost-effectiveness. For instance, [PERSON] [15] introduced constrained layer damping with a viscoelastic material as a mechanical engineering technique for vibration suppression on plate and beam structures. [PERSON] et al. [16] examined the feasibility and applicability of polyimide tape with viscous lamina for vibration attenuation of onboard electrical devices or subsystems of a small satellite under launch vibration loads. [PERSON] et al. [17]evaluated a PCB employing multilayered stiffeners attached by viscoelastic acrylic tapes in a wedge lock to enhance the fatigue life of solder joints under vibration environments. [PERSON] et al. [18] investigated the effectiveness of the constrained layer damping strategy for launch vibration attenuation on a panel by varying the number of stiffener attachment conditions. After the successful operation of 1U sized nano-class satellite Space Technology Experimental Project CubeSat Laboratory (STEP Cube Lab) [19] for technology demonstration missions in 2017, the Space Technology Synthesis Laboratory (STSL) of Chosun University is developing multispectral earth observation 6U CubeSat \"STEP Cube Lab-II\" as part of the 2019 cube satellite contest hosted by the Korea Aerospace Research Institute (KARI) that is financially supported by the Ministry of Science and ICT (MSIT) of the Republic of Korea. The CubeSat is scheduled to be launched into space in the fourth quarter of 2022 using the Korea Space Launch Vehicle (Nuri). The main objective of STEP Cube Lab-II is to carry out the nation's first multi-band earth observation mission on various targets of the Korean peninsula through the CubeSat platform. The secondary objectives are the in-orbit verification of domestically developed space technologies for forthcoming space programs.