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wheremsc iis the initial spacecraft mass, and piis the semiparameter of the initial orbit andpfis thesemiparameter of the final orbit. The upper bound on true longitude L allows for a maximum of 200complete orbits during the transfer.Finally, the components of the unit thrust vector are constrained as follows:Technical discussion1.1 u 1.11.1 u 1.11.1 u 1.1The modified equinoctial orbital elements are a set of orbital elements that are useful for trajectoryanalysis and optimization. They are valid for circular, elliptic, and hyperbolic orbits. These equationsexhibit no singularity for zero eccentricity and orbital inclinations equal to 0 and 90 degrees. However,two components of the orbital element set are singular for an orbital inclination of 180 degrees.The relationship between direct modified equinoctial and classical orbital elements is defined by thefollowing definitionsrtn21 cosp a e f e g esin h tan i 2 cosk tan i 2 sin L wherep a e i L semiparametersemimajor axisorbital eccentricityorbital inclinationargument of periapsisright ascension of the ascending nodetrue anomalytrue longitudeThe relationship between classical and modified equinoctial orbital elements is:psemimajor axis a 2 21 f gorbital eccentricity2 2e f gorbital inclination i 2 tan 1 h 2 k2page 16