Why the hell would we depend on viruses? Hell, our viruses can't infect most life on our own planet. We would send over germs, fungi and bacteria that would eat them alive.
But you were the one that said "virus bomb". And the common cold is a virus, so really it shouldn't have worked in War of the Worlds.
"Virus bomb" is an exterminatus technique from warhammer 40k, wherein specially engineered virii are dropped onto a planet, infecting all organic life in minutes, and turning them into hydrocarbon factories, until you end up with a planet covered in dead sacs of goo spraying lighter fluid into the air, at which point an incendiary is dropped turning the planet into one big fuel-air bomb.
It doesn't matter how much they could fit on a single ship. If they could make the journey multiple times, it stands to reason they could send multiple ships at once, and nuke everything from orbit.
So it costs exactly the same amount of money to send one ship that it does to send multiple ships, loaded down with extremely high mass payloads to boot, which will not in any way make back their cost in actual aquisition of the ore.
I'm starting to wonder here; are you just deliberately being obtuse, or do you literally not have a basic understanding of physics, politics and economics?
How did we go from debating weather or not they could come back, to there carrying capacity?
That's what i was debating the entire time; my point was that the reason why there were no heavy-duty war machines on Pandora was due to the mass restriction when travelling in space.
Anyway, i think that they would have enough to bring a few heavy duty bomber with actual bombs.
Maybe, but such machines are a pretty heavy cost, especially since they won't make any money once the conflict is over. Furthermore taking heavy military equipment to Pandora would have raised all sorts of eyebrows back home, a bit of a fistfight with the natives is one thing, and expected, but full out war is something else entirely and would most certainly be frowned upon. Finally, in an environment like Pandora, against geurilla forces like the Na'vi, bombers are pretty useless anyway (America found that out in Vietnam, and then found it out again in Afghanistan, and then again in Iraq, they're slow learners.)
The General's entire concept that taking out the tree of souls would stop the entire Na'vi race cold is rediculous. It would merely enrage them; i'm sure there are other trees of souls, indeed we know that there was an entire grove of similar trees. The destruction of that one tree would have merely enraged the Na'vi further and resulted in larger and more powerful geurilla forces. The Genius Loci that is Pandora itself also decided it didn't much like the idea of the 'Sky People' blowing up the tree, and responded accordingly, had they actually blown up the tree Pandora probably would have beaten the shit out of them in retaliation.
Face it, when you're up against an entire planet, you lose. (We're not in the 40K universe, so no planet killers. Sorry guys.)
Seriously, half the arguments i see being put forth here are using technology of which there is no evidence in the movie. I could solve everyone's problems with an infinite energy machine from [INSERT SCI-FI BOOK HERE], but the Avatar world doesn't have those, so the bloody point is moot.