However, all of these expectations need to be verified. Very little is known about the spatial variation of the hydrogen escape flux. Results from these measurements would constitute a great step forward in our understanding of the earth's hydrogen budget. This may be possible because of the unique way measurements will be made. Similarly, although CH 4 is not expected to be present at these altitudes, a search for methane should be made.
Photochemical models predict an abundance below the measurement threshold.
However, to have a complete picture of the hydrogen budget, a confirmation of the absence of methane is necessary. Meteoritic ablation in the atmosphere is a major source of metallic atoms. A rapid measurement time response is necessary to follow variations in the meteoritic gas concentrations along the orbital path. Since such variations may be the result of gravity waves, the mapping of such variations is an effective way of determining the amplitudes, wavelengths, and extent of gravity activity at this altitude. Schunk, R. W. and E. P. Szuszczweicz, First principle and empirical modelling of the global-scale ionosphere, Ann.