Lee Boland

Antennas for small satellites

Small low-cost satellites, pioneered at Surrey, are revolutionizing space. This paper gives an overview of antenna technologies for applications in small satellites. First, an introduction to small satellites and their structure is presented. This is followed by a description of the technical challenges of antenna design for small satellites. Various antennas for small satellite applications are illustrated. A conclusion and future work at Surrey Space Centre (SSC) and Surrey Satellite Technology (SSTL) is presented in the end.

Launch of the international Disaster Monitoring Constellation; the development of a novel international partnership in space

Three spacecraft for the UK, Turkey and Nigeria were launched together in September 2003, to join Algerias satellite, AlSat-1, in the Disaster Monitoring Constellation (DMC). Surrey Satellite Technology Ltd. has designed, built and launched the worlds first constellation to provide daily global Earth observation coverage at moderate resolution in three spectral bands. This international initiative will provide daily images for global disaster monitoring, as well as supporting each partner nations indigenous remote sensing requirements. The DMC programme establishes a novel model for international collaboration, and demonstrates how small satellite missions can be employed for a wide range of applications. This paper shows the first in-orbit mission results from DMC satellites including examples of unique EO data products comprising up to 600/spl times/600 km images gathered at 32-metres GSD in 3 spectral bands.

Second generation disaster-monitoring microsatellite platform

Abstract Earth Observation satellites have traditionally been expensive to develop and launch and, as a consequence, have been targeted to cover the diverse needs of a large user community. Many niche applications in remote sensing are not exploited to their full potential or operating on a profitable basis and, as a result, space-based Earth Observation has not yet made a similar impact into our everyday lives when compared with satellite communications. Small satellite technology however has come of age and Earth observation instrument technology has advanced to levels permitting high quality sensors to be flown on small inexpensive satellite platforms. Many examples of such missions have returned increasingly sophisticated imagery and have been well documented. As well as offering in-orbit ‘shutter control’ to small groups and specialist organisations, these satellites can be individually tailored to specific applications with custom sensors, filters, swath width, and Ground Sampling Distance. Surrey Satellite Technology Ltd. (SSTL) has been at the forefront of developing innovative Earth Observation missions for the past decade, using small satellites covering a mass range of 5kg to 300kg. Recent missions have demonstrated remote inspection, high quality multispectral imaging at Ground Sampling Distances (GSD) of 30m and panchromatic imaging at a GSD of 10m. Currently a disaster-monitoring network of five microsatellites is under construction by SSTL within an international partnership to capitalise on these small satellite capabilities. It will offer a system with a temporal resolution of daily global coverage providing rapid multi-spectral imagery of wide-swath 30m GSD to the disaster relief community. In order to expand the capabilities of such a network, Surrey is now developing a follow-on network based on a second-generation spacecraft platform, and a small satellite platform has been developed specifically to meet generic small satellite Earth Observation applications as part of a constellation. It allows the visible-band imaging network under development to be expanded to serve more advanced applications within disaster monitoring with sensors such as IR, ocean colour, hyperspectral, high resolution imagery, and even Synthetic Aperture Radar.

Moving Towards Commercial Earth Observation Services with Small Satellite Constellations

This paper outlines the heritage and future plans of SSTL in enabling high performance cost effective Earth observation services through constellations of small spacecraft. The paper will discuss two new spacecraft for customers in Spain and Nigeria, and how these meet traditional needs for Earth Observation data at a low cost. The range of payload options which SSTL can offer for a wide variety of Earth imaging applications covering high and medium resolution, wide area coverage, frequent revisits and near real-time tasking and data return in various wavebands, including visible light and microwave will be discussed. Applications enabled through SSTL’s heritage platform capability, the optical payload group (formerly Sira Space group) and SSTL’s business unit DMC Imaging International, DMCii will be discussed to illustrate the utility of small satellites for real, commercial applications.

ALSAT-1 First Year in Orbit

The role of satellites in medium and high-resolution reconnaissance of the Earth has been well demonstrated in recent years through missions such as Landsat, SPOT, IKONOS, EROS, ImageSat and Quickbird. Medium resolution data products have added significantly to Earth science, but commercial markets have concentrated on enhancing resolution. The markets for such high-resolution data products are well served, and are likely to become more competitive with further planned high-resolution missions. The small satellite sector has concentrated on reducing the cost of specialised data products that are ill served by current missions, and on the development of systems providing niche services. One such area where smaller satellites can provide a distinct advantage is in meeting the needs for higher temporal resolution, as this typically requires multiple satellites to operate as a constellation. Such a system has been discussed widely in the disaster monitoring community, Surrey is currently engaged in launching its first constellation to provide daily global coverage at moderate resolution in three spectral bands, as part of a system to provide global disaster monitoring. The first spacecraft in this Disaster Monitoring Constellation (DMC), ALSAT-1, was launched in late 2002. The programme employs novel models for international collaboration, and demonstrates how small satellite missions can be employed in emerging applications. This paper provides an overview of the DMC programme, details the ALSAT-1 spacecraft and payload, and provides the first in-orbit mission results from ALSAT-1. The paper also addresses the future of the programme, and an update of the second DMC launch due in August 2003. The latest results of the 3rd DMC Consortium meeting will also be reviewed.