UoSAT-12 minisatellite for high performance earth observation at low cost

Abstract

Surrey Satellite Technology Ltd (SSTL) at the University of Surrey (UK) has pioneered cost-effective satellite engineering techniques for smaller, faster and cheaper satellites to provide affordable access to space. SSTL has designed, built, launched and operated a series of twelve 50 kg microsatellites in low Earth orbit which carry a wide range of satellite communications, space science, remote sensing and in-orbit technology demonstration payloads—for both civil and military applications. Eight of SSTL’s microsatellites have carried CCD Earth imaging cameras, coupled with powerful onboard processing computers which have demonstrated the capability of this new generation of low-cost, rapid-response, modern small satellites. SSTL has recently developed an advanced 250 kg minisatellite platform to meet the needs of future low-cost Earth observation and remote sensing applications. With enhanced payload mass and volume, attitude stability and communications capabilities, this new platform will support more sophisticated payloads than the minimalist microsatellites. The experimental UoSAT-12 mission, to be launched into LEO in 1997, will carry high resolution and multispectral remote sensing payloads to demonstrate imaging not currently practicable on existing microsatellites. This paper reviews the design and characteristics of the UoSAT-12 imaging payloads which include multispectral cameras providing 40 m ground resolution with an 80 km swath width, and a panchromatic imaging instrument providing 10 m resolution. The trade-off between linear pushbroom sensors and area CCD cameras, and the role of on-board processing for automatic image processing is presented. These techniques enable small, low-cost minisatellites to approach the performance of conventional Earth observation satellites—but at a fraction of the cost. This pioneering work by Surrey on advanced microsatellites and minisatellites has resulted in imaging missions that can respond rapidly to customer requirements, which are affordable to a far wider community of individual commercial or governmental organizations, and which provide emerging space nations with an independent Earth observation capability.