TOPography EXperiment (TOPEX) for ocean circulation (otherwise known as Poseidon) was launched on August 10, 1992 and was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionise oceanography by proving the value of satellite ocean observations.

Centre for the observation of Air-Sea Interaction and fluXes (CASIX) was responsible for the UK contribution to international TOPEX programme, undertaken as part of the National Centre for Earth Observation (NCEO).