Keywords
Citation
(1998), "Sira completes delivery of Europe's global ozone-watch units", Sensor Review, Vol. 18 No. 4. https://doi.org/10.1108/sr.1998.08718dab.002
Publisher
:Emerald Group Publishing Limited
Copyright © 1998, MCB UP Limited
Sira completes delivery of Europe's global ozone-watch units
Sira completes delivery of Europe's global ozone-watch units
Keywords Aerospace, Environmental monitoring, Infrared, Ultra violet
Sira Electro-Optics has now delivered all of the final flight models of the global ozone-watch units it has designed and built for the European Space Agency's space-based global ozone monitoring by occultation of stars (GOMOS) instrument (see Plate 1).
GOMOS will monitor the Earth's ozone layer and the layer's long-term depletion from ESA's ENVISAT environmental-monitoring satellite, which is planned to be launched by the Ariane launcher in 1999 into a sun-synchronous polar orbit about 800km above the Earth.
The GOMOS instrument consists of an ultra violet/visible spectrometer and a near infra-red spectrometer, both fed by a single, fixed telescope mounted behind a steerable front mirror.
Plate 1 Sira Electro-Optics has now
delivered all of the final flight models of the global ozone-watch units it has
designed and built for the European Space Agency's space-based GOMOS instrument
Chislehurst-based Sira has built GOMOS' near-infra red and ultra violet/visible spectrometer detection modules, its star acquisition and tracking units, and a specially designed fast photometer.
GOMOS will enable accurate mapping of the ozone layer and will watch closely long-term trends in the amount and distribution of ozone around the Earth. Over the period of its mission, the instrument will be able to measure ozone concentration decreases as small as 0.1 per cent per year, well below depletions expected from model calculations.
Detailed worldwide daily maps at every altitude between 15km and 60km or more will be produced by GOMOS, which will provide full Earth coverage and as much data as 360 ground-based stations.
Measurements will be made by orienting GOMOS' line of sight, using the steerable mirror, towards preselected stars while they are setting behind the atmosphere at the horizon. By observing the full ultra violet-visible-near-infra red spectrum of the star and employing a self-calibration method, GOMOS will provide an absolute measure of the concentration of atmospheric molecules present.
The location of each of these concentration measurements will be accurate to ±30m through the atmosphere and stratosphere extending up to 60km from the Earth's surface.
In addition to monitoring seasonal, latitudinal and long-term trends in ozone depletion, GOMOS will also measure other atmospheric molecules and parameters, such as NO2, NO3, H2O aerosols and vertical temperature distribution, to provide a better understanding of the ozone depletion mechanism.
Sira has been working as part of an international team headed by Matra Marconi Space, reporting to ESA's prime contractor, Dornier.
For further information contact Sandy Deane, Sira Electro-Optics Ltd, South Hill, Chislehurst, Kent BR7 5EH, UK. Tel: +44 (0)181 467 2636.