Proving UK technology
TopSat was conceived as part of a Government-funded small satellite
programme called MOSAIC (Microsatellite Applications in Collaboration
programme). The satellite is known as a 'technology demonstrator' and has been
built to show that even a small box-shaped spacecraft of roughly 80 cm across
can deliver impressive results.
Costing £14 million, TopSat is many times cheaper than traditional
satellite missions. The single instrument on board is an extremely powerful
camera designed to provide visual images from space with a resolution of 2.8 m.
This is good enough to pick out individual houses, or even vehicles, from
TopSat images can be used for a variety of applications including mapping or
land-use monitoring. Images are used by a variety of customers including the
Ministry of Defence and UK universities. TopSat images are also being provided
free of charge to relief agencies responding to disasters anywhere in the
The spacecraft operates within the International
Charter: Space and Major Disasters, which enables satellite data to be used
to help those affected by natural or man made disasters.
The spacecraft is only one part of the TopSat mission. As the aim is to
deliver high resolution images to any area on Earth, the project also includes
a special lightweight portable ground station.
TopSat has proved that a simple, economically built spacecraft can achieve
the same calibre of results as traditional satellites. The basic design can be
readily adapted for different instruments or applications.
The secret of keeping the cost down was in the design of the craft itself.
To ensure it stays as compact as possible, TopSat has no extendable solar
panels and very few moving parts.
The team building the satellite were able to re-use parts of previous
spacecraft. This helped to reduce the cost of the mission even further.
The primary instrument on board TopSat is an extremely powerful camera
capable of providing a resolution of 2.8 m from TopSat's orbit of 686 km above
the Earth. Normally a camera this powerful would have to be very long so would
not fit into a spacecraft just 80 cm wide. However, the designers at STFC
Rutherford Appleton Laboratory managed to create a compact, box-like design by
including three mirrors in the instrument.
TopSat could also carry other payloads. Rather than a camera it might be an
alternative imaging device, monitoring or communications equipment.
TopSat was conceived, designed and built in the UK. It was jointly funded by
BNSC and the Ministry of Defence. The following companies all had key
involvement in the project: