Abstract: A new analytic linear covariance method for powered explicit guidance（PEG）is proposed, and the method is capable of obtaining the explicit expressions of PEG’s three parameters. The method is applied to analyze the final altitude dispersion, velocity magnitude dispersion and flight path angle dispersion with the existence of original state errors and parameter uncertainties in the lunar powered ascent phase. In contrast with Monte Carlo simulation results, the method is proved to be valid.

Key words: linear covariance;lunar powered ascent phase, PEG