RADARSAT-2 is an earth observation satellite project, developed in Canada, to aid maritime navigation, natural resource identification and monitoring, management of agricultural and water resources, and monitoring of ice and other environmental changes. RADARSAT-2 will eventually replace RADARSAT-1 (launched in 1995). This article provides a high-level description of one of the spacecraft modules, the extendible support structure (ESS). The ESS is a mechanism designed to deploy and support the synthetic aperture radar (SAR) panels in a precise configuration once on orbit. As such, the performance of the ESS is critical to the overall success of the RADARSAT-2 mission.