Planning Space Campaigns and Missions

Abstract

In the early stages of designing a mission to Mars, an important measure of the mission cost is the initial mass in LEO (IMLEO). A significant portion of this mass consists of propellants. Space missions can be described in terms of a series of states connected by steps. A state is a condition of relative stability and constancy. A step is an action of change (e.g. fire a rocket). Using state-step data, one can estimate the initial mass in LEO for delivery of payloads to Mars orbit and the Mars surface. In any mission design, the first and foremost thing that is needed is the set of Δv for all the mission steps. Estimates of Δv for various steps can be made by standard trajectory analysis. The propellant requirements for each step can be estimated from Δv. It requires a great deal of IMLEO to send a spacecraft to Mars orbit and back. It takes even more IMLEO to send mass to the Mars surface and back. Unfortunately, in typical NASA reports describing future space missions, ferreting out state-step information is time-consuming and frustrating, and is usually impeded by missing or ill-defined data. Therefore, it is difficult to trace through the steps of NASA concepts for human missions to Mars.