Hey guys, apparently you can't read so well. The grant is for an individual who develops a business plan to do this, not for a space ship.
DARPA (which basically serves as the blue sky research body of the government) wants to toss around a little money and get people thinking what kind of organization or purpose it would take to get something like this going. And they want it to be a private venture, not a government funded one.
So, you know, once you get your eyes on the actual words it pretty much takes a big steamer on your objections.
Moving on to the actual grant.
The problem with a business plan for this is the same one Europeans faced in their exploration of the world. The only real business plan is to take something from Point A (the exoplanet) and return with it to Point B (earth, where the money is). In order to pay for those ships and crews and colonists, the merchant adventurers needed something with a high value to volume and weight ratio: gold and spices for the most part. As traffic increased and the value of those goods started dropping, more and more ships started taking on bulk cargo like naval stores, tea, tobacco, linens, etc.
So what sort of thing would be profitable enough to pay for a voyage of ~25 to ~50 years between stars, that isn't organic (because it would likely die en route OR if it could survive the trip could probably then be bred on earth, making it a one time trip), isn't available on earth (but available on an earth-like exoplanet) in sufficient quantities, and wouldn't take up a lot of space?
You're pretty much left with a few articles:
-fossil fuels: we'll be running short of them in an hundred years at current rates of consumption, but presumably those won't be all that necessary in the future
-uranium and other fissile materials: assuming we never develop viable commercial fusion, we'll need them in mass quantities (renewable is nice and all, but it isn't viable for handling base loads; fission can provide that sort of steady, reliable power without raping a river system)
We'll pretend that in the distant future the prices justify shipping these goods. But what about the return leg. Presumably colonists have the ability to produce their own goods, otherwise they'd all die waiting for the return of the ship (after 50 years? definitely so). There's a growing body of thought that the 3D Printing stuff going about will allow made to order manufactured goods to be produced from the comfort of a home or local shop, so no reason to ship finished goods across a few ly. That leaves cultural goods and information as the only potential item of interest, both of which can be shipped in mass quantities in compact forms.
In the end it'd be easiest to send shielded drones with stacks of hard drives from one location to the other, or even better beam the information at the speed of light between the two locations -- difficult to pull off, but definitely possible and certainly cheaper and faster than a stack of hard drives.
The third option is the one where we develop biological control mechanisms and simply fire printers capable of outputting organic explorers who can be controlled by human operators from the comfort of earth, probably through some quantum communication method.
If communication ends up instant (the great hope of quantum mechanics) then distance becomes irrelevant and people can be sent off to distant planets to colonize and expand without it mattering the slightest -- they'd be able to produce code or write novels far away and generate income for themselves and those who wish to start more service oriented businesses like restaurants or banks or law firms. But if communication is slow and expensive at the interstellar level, earth based options will be our only real recourse unless we wish to send people off and never hear from them again (a silly and useless idea).
