Implementation of Wire Burn Deployment Mechanism Using COTS Resistors and Related Investigations

The most common method of deployment of mechanisms in Pico- and Nano-satellites is the Burn Wire release mechanism. Traditionally, the wire burn mechanism used in deployment mechanisms employ a nichrome wire. This paper presents the shortcomings of the use of nichrome wires and suggests using an off-the-shelf resistor as an alternative. The observations and conclusions are a result of the implementation of the solution above in a student nanosatellite. In the concerned nanosatellite commercially available off-the-shelf carbon film resistors were made use of for the thermal cleavage of the polymer braid in its wire burn mechanism. The resistor helped overcome the limitations and complications encountered in the use of the nichrome wire for the same mechanism. The resistor helped make the mechanism more compact, easy to stow and assemble, and reliable. It also allowed for simpler mechanism design and reduced the number of points of failures. The use of nichrome wire mandates that both the nichrome wire and the retention wire be taut and be firmly in contact with each other for the successful functioning of the mechanism. This causes an inconvenience as setups must be devised to keep both wires in tension. Moreover, the failure of either of the setups can significantly affect the overall performance. The release mechanism uses a nichrome wire to cleave a fiber braid (usually a polymer) thermally. This simple mechanism ensures high effectiveness and reliability. The reliability of the system is dependent on the amount of contact pressure between the nichrome wire and the polymer braid. Insufficient contact pressure may result in the fiber not cleaving at all. Hence a repeatable and measurable method to induce the required contact pressure is necessary. The tension in the polymer fiber directly corresponds to the contact pressure between it and the heating element. This paper demonstrates the implementation of a fiber tensioner in a nanosatellite. The tensioner maintains required tension at all times. The tensioner is efficient, light, and is easily machined. Additionally, the resistor allows for the implementation of a surge generation circuitry which allows the safe dissipation of a large amount of energy in a very short interval of time, maximizing the success rate of the deployment. The energy dissipation rate achieved by such circuits simply cannot be achieved in a nichrome wire setup. This paper presents the design of the mechanism and highlights the advantages of the use of a resistor. It also shows the mechanism test results as a demonstration of the systems reliability. A comparison between the above two systems regarding reliability and point of failures is also performed. The most common method of deployment of mechanisms in Pico- and Nano-satellites is the Burn wire release mechanism. The system has high repeatability. This paper presents the design philosophy and process, and the reliability and repeatability test results of the same. The susceptibility of the system against vibrations is also evaluated. The system calibration techniques and results are also presented.