Occultation ray periapsis loci with high vertical and low horizontal velocities typically provide the most accurate and numerically stable measure of a planetary atmosphere. A ray periapsis with a low horizontal velocity also has the advantage that it samples the smallest possible atmospheric volume. Such a condition may be achieved by placing low altitude, mutually occulting satellites in the same orbital plane. Moreover, if the satellites move in opposite directions, a large number of distributed, very high quality occultations will occur daily. There are trade-offs between optimal geometries and ease of instrumentation.
Simple rules govern the number and distribution of the mutual occultation points.
Arbitrary orbital geometries typically provide only mediocre observational conditions.