SPACE AND AIRCRAFT SENSORS

Metal oxide-based semiconducting sensors offer a promising solution fo r various measurement problems of practically all the small constituen ts in the atmospheres of the Earth and other planets. These sensors ma y be installed in various flying objects. The basic sensor parameters essential for these experiments are: sensitivity, rapid action and sel ectivity of data acquisition. The main advantage of these sensors is t he possibility of making highly sensitive measurements of molecules (0 2, H-2, Cl2, etc.) in the ground state and also of chemically active p articles (free atoms: H, 0, Cl, N, etc.; radicals: OH, CH3, NH2, etc.; vibrationally excited molecules: O2v=1, N2v=1, Cl2v=1, H-2v=1 and the ir isotopes; electronically excited molecules: 02 (1DELTA(g)); metasta ble atoms of inert gases). The sensitivity of the sensors to free atom s and radicals is 10(6)-10(8) cm-3, that is two to three orders of mag nitude higher than for excited molecules and three to six orders highe r than for molecules in the ground state. In spite of the exciting sol utions of some selectivity problems for the simplest particles (O and O2, 0 and H, H and OH, O2v=1, 02 (1DELTA(g)) and 0), the problem of se lectivity as a whole is far from being settled. A sensor system for 0 atoms installed in a meteorocket has been constructed and successfully examined in an experiment in the upper Earth's atmosphere.