Design and Development of CubeSat Solar Array Deployment Mechanisms Using  Shape Memory Alloys  Allen Guzik* and Othmane Benafan*  Abstract  The Advanced eLectrical Bus (ALBus) project is a technology demonstration mission of a 3U CubeSat with  an advanced, digitally controlled electrical power system capability and the novel use of Shape Memory  Alloy (SMA) technology for reliable solar array (SA) deployable mechanisms. The ALBus CubeSat deploys  four SAs in addition to the body-mounted arrays on each side of the CubeSat. A goal of the mission is to  utilize the SMAs being developed at the NASA Glenn Research Center to deploy these SAs. The use of  SMAs allows for the ability to test and reset the flight deployment mechanism prior to flight, which reduces  the risk of in orbit deployment failures common to CubeSats. As a result, an SMA-driven Retention and  Release (R&R) mechanism and an SMA-driven hinge were designed, developed, and integrated for flight.  This paper summarizes the development of these mechanisms, types and functionalities of the SMAs used,  as well as the lessons learned throughout the process.  Introduction  CubeSats are a high-risk, usually secondary payload, mission. They conform to the CubeSat Design  Specification [1] and come in standard “U” sizes. A 1U CubeSat is a spacecraft with dimensions of 10 cm³.  The Advanced eLectrical Bus (ALBus) spacecraft is a 3U size CubeSat roughly measuring 10 cm² by 30  cm long. The main mission goal of ALBus is to act as a technology demonstrator with an advanced, digitally  controlled electrical power system capable of distributing 100 W of power. Typically, CubeSats operate in  the 5 to 20 W power range. A higher power distribution capability opens more opportunities for CubeSat  mission payloads, experiments, and functions, including propulsion and advanced communication. ALBus  is not capable of generating 100 W continuously, so it uses SAs to store electrical power in batteries until  enough power has been stored to test distributing 100 W of electrical power. To reduce the amount of time  to charge the batteries, additional deployable SAs were added to the design. This drove the second mission  goal, which is to leverage the SMAs being developed at Glenn as a way to deploy the SAs.   Flying and operating CubeSats have been a risky endeavor with a 40% failure rate of university class  CubeSats [2]. Of those failures, less than 10% can be attributed to the mechanisms, however, 33% fail for  unknown reasons [3]. A way to improve on this failure rate is to increase the reliability of the deployment  mechanisms. Common deployment methods consist of nichrome burn wires to burn through a strap or  tether [4]. This can fail by the burn wire shorting out prior to burning through the release strap or the strap  getting tangled upon deployment. Another technique comprises of breakable links made of plastic retaining  bars that are heated and burned [5]. While the latter is advantageous in securing the hardware from  vibration damages, both methods employ consumables and do not allow direct testing of the actual flight  hardware since parts are destroyed during the deployment and new hardware is needed to reconfigure the  spacecraft into the stowed configuration. The deployment mechanisms designed for the ALBus are an  attempt to eliminate all deployment consumables (or even human factors like winding strap wire) to allow a  reliable and resettable means to deploy structures on a CubeSat. In this work, SMAs are used to deploy  SAs and allow them to be functioned and tested on the ground with the same hardware that will be used  during the flight mission.  *NASA Glenn Research Center, Cleveland OH Proceedings of the 44th Aerospace Mechanisms Symposium, NASA Glenn Research Center, May 16-18, 2018 NASA/CP—2018-219887 375