Statistical Delta-V Tool for Pre-proposal Studies (DV99)

For any space mission proposal it is essential to provide an accurate, defensible estimate of the total propellant ("Delta-V") budget, including the Delta-V required to correct for statistical errors. We will develop tools to provide an accurate analysis to a 99% confidence level of the statistical Delta-V required to correct for launch dispersion, orbit determination error and maneuver execution error. For this analysis we plan to use a nonlinear propagation technique using sigma-points based on the Unscented Transform to map the dispersions of a nonlinear control into a covariance matrix as well as linear covariance propagation techniques as a benchmark for the nonlinear propagations.

The goal of this project is to develop a software tool for pre-proposal and concept studies to provide an accurate, defensible estimate of a statistical Delta-V to a 99% confidence level (DV99). We plan to apply both linear and nonlinear covariance propagation techniques in this tool, to estimate the magnitudes of Trajectory Correction Maneuvers (TCMs). Nonlinear propagation will be needed to handle the nonlinear control laws where linear propagation may not be sufficiently accurate for example during a lunar flybys.

In this analysis we plan to leverage the Orbit Determination Tool Box (ODTBX), an open-source MATLAB-based software library. In particular we will make use of the covariance propagation and sigma-point transformation capabilities. Where appropriate, we will contribute new functions to ODTBX.

This project is a collaborative effort between NASA Goddard Space Flight Center and Johns Hopkins Applied Physics Laboratory.