The TopSat being made
Mission typeOptical imaging
COSPAR ID2005-043B[1]
SATCAT no.28891Edit this on Wikidata
Spacecraft properties
Start of mission
Launch date27 October 2005, 06:52:26 (2005-10-27UTC06:52:26Z) UTC
Launch sitePlesetsk 132/1
Orbital parameters
Reference systemGeocentric
Perigee altitude682 kilometres (424 mi)[2]
Apogee altitude707 kilometres (439 mi)[2]
Inclination98.18 degrees[2]
Period98.65 minutes[2]
Epoch3 November 2005[2]

TopSat (Tactical Operational Satellite, also known as TopSat 1 and TacSat 0) is a British Earth observation satellite, currently in Low Earth Orbit. The nanosatellite was launched in October 2005 alongside the Beijing-1 Disaster Monitoring Constellation satellite by a Cosmos rocket from Plesetsk Cosmodrome in Russia.[3]


TopSat carries out imaging with a ground resolution of 2.5 m. Much smaller and cheaper than other imaging satellites of similar high resolution, TopSat has been used to demonstrate the feasibility of providing images on demand to portable ground stations, such as that which might be deployed by the military or another disaster relief organisation.

TopSat was built in the United Kingdom by Surrey Satellite Technology Ltd, QinetiQ and The Rutherford Appleton Laboratory under the British National Space Centre Mosaic programme. The engineering model of TopSat now lives in the space gallery of London's Science Museum.[4]

TopSat won the 2006 Popular Science "Best of What's New" Grand Award in the Aviation and Space category.[5]


  1. ^ "CelesTrak SATCAT: 2005-043".
  2. ^ a b c d e McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 3 May 2018.
  3. ^ "TopSat". UK Space Agency. Retrieved 25 June 2012.
  4. ^ Transcript: Stuart Eves interviewed at the 2008 UK Space Conference Archived 2008-12-09 at the Wayback Machine
  5. ^ Popular Science "Best of What's New" Grand Award, Science and Technology to TopSat.