A human mission to Mars would likely involve several vehicle elements that are staged near Earth, and the choice of staging location can significantly affect the efficiency and robustness of a Mars exploration campaign. The key figures of merit are overall AV, departure windows, backup opportunities, and contingency options. These characteristics are detailed and compared for Earth-Moon L_2, high-lunar orbit, high-Earth orbit, and low-Earth orbit. Earth-Moon L_2 and high-lunar orbit are found to be operationally and energetically similar, and require additional AV to enter and depart before leaving for Mars. High-Earth orbit enables trans-Mars injection backup opportunities by reorienting the orbit at apogee. This type of orbit can shift between many inclinations, periods, and perigees with lunar gravity assists. Direct departure from low-Earth orbit requires the fewest number of critical maneuvers, but does not benefit from potential efficiencies from solar electric propulsion or reuse of deep space vehicles.
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