The SPOT Family Heritage

The multimission platform was first developed during the early 1980's, initially to support the SPOT optical imagery mission. The original Mark 1 version of the platform has been used for five satellites, including ERS-1 and ERS-2. Four of these remain operational; SPOT 3 was lost in late 1996 following an on-board anomaly. It failed to enter Safe Mode due to excessive spin rate.

Extensive upgrades to the avionics led to the development of the MkII platform, initially designed for SPOT 4 and Helios 1. This version has a new solar array design delivering more power than the Mk I array. This platform was taken as the basis for Envisat with a number of modifications:

• new structure;
• some modified (4) or new (3) avionics units;
• new solar array delivering substantially more power;
• modifications in AOCS software
• new thermal control subsystem.

Since Envisat the platform has further evolved, mainly through the improvement of avionics, to lead to the Mk III platform.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry