Abstract
Small satellites, weighting between 100 to 200 kg, have witnessed increasing use for a variety of space applications including remote sensing constellations and technology demonstrations. The energy storage/stored power demands of most spacecraft, including small satellites, are currently accommodated by rechargeable batteries - typically nickel-cadmium cells (specific energy of 50Wh-kg-1) in the past, or more recently lithium-ion cells (150Wh-kg-1). High energy density is a primary concern for spacecraft energy storage design, and these batteries have been sufficient for most applications. However, constraints on the allowable on-board battery size have limited peak power performance such that the maximum power supply capability of small satellites currently ranges between only 70 and 200W. This low maximum power limits the capabilities of small satellites in terms of payload design and selection. In order to enhance these satellites’ power performance, this research focused on the implementation of super-capacitors as practical rechargeable energy storage medium, and as an alternative to chemical batteries. Compared to batteries, some super-capacitors are able to supply high power at high energy-efficiency, but unfortunately they still have a very low energy density (5-30Wh-kg-1). However, the provision of this high power capability would considerably widen the range of small satellite applications. This research pioneered the feasibility and the effectiveness assessments of a new power system that uses super-capacitors as on-board energy storage medium. Implementation of commercial-off-the-shelf (COTS) super-capacitors to the spacecraft power system has potential obstacles to overcome, namely, lower energy density, interface compatibility, and launch and space environment survivability. To investigate these questioned elements, a feasibility study, prototype development and space environmental test were carried out. The super-capacitor has shown a promising increase in their capability of supplying power of 1 to 2kW without significant rise in the overall power system mass. Hence choosing supercapacitors over conventional battery technology would result in a breakthrough in terms of platform choice for payloads.