FYI, doing a space combat 'section' of a ground combat game would require us to create 2 completely different games (double the time, resources, budget, and add some extra time for management of such a behemoth project), and then somehow marry them together. I'm not saying it is impossible, but its probably not wise.
Even if you only did the space part for a couple of missions that doesn't really cut down the investment, because you've still got to create a good space combat game on top of a good ground combat game.