Space telescope observations of the earth's upper atmosphere by stellar occultations

Stellar occultations provide a useful means of measuring the trace gas composition of the Earth's mesosphere with a sensitivity of order one part per billion. The operational details will differ from those of other astronomical observations by ST, because of the difficulties in guiding near the Earth's limb. Two specific trace gases of interest to atmospheric studies, C$\text{l}$ and C$\text{l}$O, are discussed in this paper.