Do we need more than one planet?

That's not true. The difficulty with invading a world was an obvious impending issue since the beginning of the kickstarter(at the latest).

A player with all his resources immediately available will have a huge advantage over a player that can only muster a portion of his resources. It doesn't take a huge play test to figure this out.

Yes and no, while one player has the home ground advantage they also stuffer from more attrition (a battle in a mass extractor field isn’t going to hurt the attacker as much). At any rate cracking a planet should take more work than taking the Next Island or mass field…

On default system:

I’m going to agree with the idea of just adding moveable moons to the current system (even just one around the starting planet). As the builds progress orbital is become more and more important, in the current public build planetary invasion is possible and having another planet for support is becoming a more vital part of the game.

On mother ships:

While I’m with MrTBSC on not having mobile unit production (this is what proxy bases and tellporters are for) a larger interplanetary unit transport with drop pod deployment to support unit cannons (more tactical vs larger quantities) is something I would love to see.

Hells yeah

It is already proved that the Teleporter isn't an invasion tool, and that you can forget about building proxy bases on a territory controlled by the enemy. Could it be a moon or a planet, it's just matter of time for your opponent to fully dominate it, specially thanks to the Area Patrol command (which is very handy, indeed).

So you're left with the Unit Cannon. Or a bunch of transporters. Both imply that you establish proxy bases nearby the planet to invade, which we already said it is impossible if the opponent already controls those area.

So, let's say that you adversary controls a Planet and its moons in that specific orbit. At Uber they told us that soon we will be able to move planets into each other orbit.

But moving planets into each other orbits makes no sense.

In fact, at that point, why can't I just splash them against each other? Where's the difference between moving a planet and splash it?

I assume that shifting planet orbits will make sense once we get the unit cannon.

Yes, but then, if you can move a planet, you can also smash it into another, right?

True, but I also assume that the destructive power of asteroid smashes will decrease (not destroying everything on the target planet).
Just speculation on my part though.
Remember than smashing an asteroid you control is also quite a sacrifice of ressource income.

Sure. Nevertheless often it is a game closing event.

Yeah, orbiting planets doesn't make much sense when you can smash them. If you can sac everything but your commander to win the game you're supposed to do it, just like chess. Unless of course you can't smash planets that are too big, but then you'd just have unit cannon and nuke wars to establish beachheads.

What about when the enemy has two planets and you only have one asteroid? We will definitely have a use for asteroids as orbital fortresses. An asteroid full of nukes and units coming right out of a teleporter onto a unit cannon will be pretty terrifying.

Yes, however it may be used for both.
Invading outer moons, or planets before smashing the final, dug in, planet.