ISO's last light and switch off
ISO was switched off on 16 May 1998 at 14:00 CEST, thereby bringing to a close the highly-successful in-orbit operations of the ISO mission. Prior to that, ISO's orbit was changed to force the satellite to burn up in the atmosphere, thus contributing to preserving the environment in space.
In fact, ISO continued to give scientific surprises to the very end. ISO's 'last light' observation -taken with the SWS instrument just before midnight on 10 May- was of emission lines from hydrogen in a hot supergiant star (eta Canis Majoris). The preliminary results show that this star, supposed to be ordinary, is probably surrounded by a disk of matter.