Artist's impression of the Nimbus-7 Earth observation satellite in orbit over Antarctica. The most notable of Nimbus-7's eight onboard instruments is the Total Ozone Mapping Spectrometer (TOMS), used to monitor total global ozone distribution. TOMS data confirmed the existence of the ozone hole over Antartica & continues (as of 1991) to monitor its growth. Nimbus-7 was launched into a near-polar 955km orbit on 24 October 1978, and remains operational far beyond its original design lifetime.