It all starts with a developer who knows their limits. Assuming a group of people could get the funding to make such a project approachable, they'd then need to figure out the most cost efficient way to realize their goal of creating a space colonization MMO. However, they would also need to make sure the game has a very unique and strong visual look. Why? If you can't wow them with graphics, then do it with art design.
I would wager that the best way to do this is to look at games like Jumpgate Evolution or Battlefield: Heroes. These are upcoming titles that both focus on being able to run on a wide breadth of machines. Let's face it, a game about colonizing space is going to need to reach as many potential players as possible, because it's just not a hugely popular wish fulfillment. So low system specs with a strong art design are a good start.
Lastly we get to business model, something that a few companies seem to have a pretty good start with at times. This is a sticky topic that can veer into all sorts of drawn out arguments and caveat-filled rhetorical questions so I'm just going to tackle it head-on. The best plan would be to go for free-to-play with a westernized approach to microtransactions. Allow players that want to play a few bucks a month to do so and receive slight bonuses that will make their play experience a bit easier. Then, offer up aesthetic choices at first and keep your finger in the water to see what the player base wants beyond that. In-game currency? Experience boosts? It's all a matter of what the community of a game is or isn't willing to purchase.
Space colonization MMO type two starts not with a living planet, but an almost dead one -- something like Mars. In this game the players wouldn't really have as much combat and instead would focus entirely on making their planet livable. While this type of game would probably be very interesting as a singleplayer title, I don't think it suits the MMO genre very well. Having zero combat is a bad choice because most people accustomed to games just aren't ready for it. The trick is to lure them in with things that are familiar and then introducing them into a whole new realm of possibilities.