Re: Someone hold Brian back.
Thought experiment: What would it be like after landing?
Let's assume a perfect trip to Mars with no zero-gravity or comic radiation concerns...
And I'll further concede a perfect landing with unlimited air and food and no solar radiation concerns...
You touch down, you don your suit and open the hatch...
You see a plain of red rocks. In all directions. Average temperature is about -100. Atmosphere is a near vacuum. Land surface area = Earth's land surface area. So what do you do?
After the initial euphoria, you kick some rocks around. Hit a golf ball. Send some twitpics.
You wonder what's over the horizon. You're an 'explorer' after all. And this is so 'cool', right?
Except you ALREADY KNOW what's over the horizon as the entire planet is mapped in 30cm/pixel resolution. MRO HiRise and Mars Express and subsequent missions have scanned the entire planet in HD. You can Google Mars it. So you're not really exploring unknown virgin territory. So what could you possibly do that warrants the $100 billion price tag?
Collect some rocks for sample return? Sure. But a rover could do that too. Slower, sure, but 1000X cheaper.
After Day #3, when you're sick of wearing the suit and breathing an artificial atmosphere and eating freeze-dried food and the sight of endless plains of red rocks, the 'cool' factor will surely start to wear thin.
How long before you're longing for the green and blue of Earth? Beaches. Bikinis. Real food. Variety of company. The wind on your face as you're driving a convertible?
For $100 billion, I'd want Pandora, not a barren monochrome frigid wasteland.