SPOT 4 Objectives
The SPOT 4 satellite added its new capabilities to the SPOT family. To ensure continuity of service, SPOT 4 had the same geometric imaging characteristics (a swath of 60 km per instrument and oblique viewing capability of 27° on each side of the local vertical). However its performance had been increased by adding a new shortwave infrared spectral band (SWIR).
The satellite operated for almost 15 years from its launch in March 1998. Over 6.8 million images of Earth were acquired.
In 2013, CNES lowered the altitude of SPOT 4 by 2.5 km to put it on a phased orbit with a five-day repeat cycle. On this orbit, SPOT 4 was programmed to acquire a time-lapse series of images over 42 sites with a five days revisit period from February to end of May 2013. The data set it produced is aimed at helping future users of the Sentinel-2 mission to learn working with time-lapse series.