IT'S NOT everyday York scientists get to use a military missile to launch an experiment instead of a nuclear warhead, but that's just what happened in Siberia this past winter.

Earth and atmospheric science Professor Ian McDade is one of four York researchers who have been working on an instrument that will measure ozone depletion. The gizmo, OSIRIS, flew aboard Odin, a satellite launched on a decommissioned ICBM.

OSIRIS is the acronym for the Canadian Space Agency's (CSA) Optical Spectrograph and InfraRed Imager System.

Scientists at both the University's Centre for Research in Earth and Space Science and Department of Earth and Atmospheric Science worked for several years on OSIRIS. Its target is the stratosphere-the layer stretching from about 12 to 50 km above Earth-and the mesosphere, varying from 50 to 100 km above Earth.

Information on Odin and OSIRIS is available by visiting www.ssc.se/ssd/ssat/odin.html.

Illustration: Rob MacDonald