Originally Posted by BacteriumFendYoke
There have been numerous proposals discussing the idea of sending deep-space probes to nearby star systems. Unfortunately the technology does not exist to do it in a human time scale. Such probes would need future or near-future technology to be able to travel at the speeds required - then you have to worry about the difficulty of transmitting meaningful data from spacecraft at least several light years away.
Add a human into that equation and you've got a whole host of other problems. A mission to Mars is viable with modern technology - in fact one of the biggest problems is shielding manned missions from solar radiation. Various studies estimate that the risk of cancer developing in an unshielded spacecraft (to one individual) is around 30%. We have the technology to counter that risk (plastics and water shielding) that would work but also add to the weight of the craft, which makes it much harder to launch. Taking humans any further than Mars is not out of the question but it would be very difficult as it currently stands.
With that said, there's no reason why other life forms couldn't have developed the technological solutions - but the chances of different life forms intersecting in time (and space, indeed) in our local area are remote. Certainly not impossible - but remote. We're much better off looking for radio transmissions.
As for Roswell? I've never seen enough to convince me of extraterrestrial origin. There's a lot of hearsay - but that's what I treat it as. I'm naturally skeptical and this hits all those buttons. Not enough hard data.
Life exists in a tiny, fast dimension, and we are trying to move into an immensely giant and slow dimension. A bacterium would have a better chance of moving itself to the other side of the Earth in its two-week life span, than we would at reaching another solar system. Those are the kinds of differences in scale we are up against.
But moving into our solar system is pretty doable, even beyond Mars. The moon has plenty of aluminum ore, which can be used for making structures and ships. A byproduct of aluminum refining is oxygen. Asteroids have lots of minerals. Venus is too hot - that planet may have had life once but got royally screwed - and some of the moons of the gas giants may have rocky surfaces. If we could develop the space elevator, that would open up space as much as the airplane opened intercontinental travel.
I thought the proposal to send people on a one-way trip to Mars was fascinating. Like 80 percent of the cost of a Mars mission is bringing people back. If we sent them there with some structures and equipment to grow food, extract water and power pressurized units, we could send occasional unmanned supply ships with anything else they needed, or even more colonists. But we are unwilling to "sacrifice" people, even as thousands of hands shot up at the prospect.