How to Conquer a Planet

I recently watched the movie "Battle Los Angeles" and I liked it more than I thought I would. It was an alien invasion/Marine recruitment video.

I also have a few thoughts for the aliens: If you can bring an army to Earth, clearly you have the technological upper-hand. Why would you even bother to land the troops? You control the high-ground. *Spoiler alert* They make it clear that your species is tracking us using our own radios and cell-phones. Wouldn't it be easier to take out our satellites and drop rocks on our major cities?

The movie did not get into the aliens motivation although it implied it was to take our precious, precious water. You could have sent a mini-team to the center of the Pacific and taken our water to your heart's content. Why the invasion?

And so people don't think that I'm rooting for the bad-guys here, let me give some suggestions to the human side. NASA was able to track the aliens spacecraft and the military was able to mobilize in time. Heck, the military was even able to track the aliens communications network and pinpoint the weak links. Let me clarify: the United States was able to track the aliens and deploy their military.

How awesome is that? The United States is the primary line of defense for the entire planet. That's a pretty serious responsibility when you think about it.

And I'm not saying that an alien invasion is likely, but wouldn't you want the ability to take the fight to them? Where's our space program? Where's our moon bases and Battlestar's ready to stop alien invaders or even rouge asteroids?

It's not the kind of thing that the private sector is likely to take up. It sounds like something that would fall to the government sector.

Also, if humans set out to conquer an alien planet, it would be good for us to have the high-ground. We don't want to needlessly sacrifice space marines.