Suppose that one of the Apollo landings had developed a fuel leak in the lunar ascent module, such that even with a lightened load, the ascent module only had enough delta-v to reach about half of lunar orbital velocity. One possible rescue solution would be to lower the command module's orbit much nearer to the lunar surface, then execute a retrograde inclined burn, placing it into a high-arching suborbital trajectory. At the same time, the ascent module would take off and aim for that same suborbital trajectory, so that the two craft would still be able to dock, albeit with a very limited window due to the free-fall condition. The command module would then re-ignite its engines and head for Earth. Assuming the command module had enough extra fuel for such a maneuver, what might the optimal launch trajectory have been? Should the command module have descended to a very low parking orbit to minimize gravity drag on the ascent module, or remained at a higher orbit to give more free-fall time? A lower orbit is faster, which means a bigger gap has to be closed between the velocities of the two modules, but a higher orbit is going to add uncertainty and suck more delta-v away from the ascent module due to gravity drag.