NASA Marshall Engineering Thermosphere model — 1999 version (MET-99) and implications for satellite lifetime predictions Original Research Article

The use of thermospheric density models in the prediction of atmospheric drag (the major perturbation for orbiting spacecraft) is of great importance. Issues associated with these predictions include lifetime estimates, orbit determination and tracking, attitude dynamics, and re-entry prediction. Logistics planning through attitude control requirements and re-boost planning are also influenced by future orbital altitude density estimates. The MET-99 model and its predecessors were developed to provide the inputs needed to address these issues. The sensitivity of the future estimation of solar activity, and thus thermospheric density and the prediction of a satelliteʹs lifetime, to the selection of Solar Cycle 23 minimum other than the conventionally identified mathematical minimum is shown. This can produce about 25 percent error in predicted satellite lifetime for a typical low Earth orbit example.