That being said, a serious manned mission to Mars would need a fairly large crew, and one with different training than modern space missions. These days, we're usually sending up highly trained specialists for specific experiments and suchlike. On a Mars expedition, while there would be some specialists, we would need a lot more people who could handle a large range of work conditions. And we would need trades people. Welders, construction people, etc.
Personally, I think that will be the sign that space is really starting to open up, and actually be useful: When we're sending electricians, welders, and other trades people into space because we need people actually capable of *building* and *repairing* things there, not just assembling them or replacing them, or doing experiments
1) Public perception. There is bound to eventually be an outcry in some sectors about the sanctity of human beings and how machines shouldn't be wired into people and vice versa, machines reading our minds, etc. If the technology has a working application of serious humane benefit, which the gov't is actually pursuing, this negates this to large extent.
2) Technological progression. If the gov't and others are putting money into it, it will most likely progress faster and more reliably than if it has to depend on commercial sources who understandably want to make money off it. And if it stops looking like it will make money... There goes the project into obscurity.
There have been numerous articles on Slashdot and various science sites on how the human brain can adapt to other forms of "senses". The vibrating belt that always indicated North, the possibility of humans learning to echonavigate, and many, many others. While the tongue is maybe not the most convenient way of integrating with our neural system, it is at least demonstrating the possibility. Once the technology starts to mature, deeper and more invasive integration starts to become possible. While I doubt we'd get to the point of being like the Matrix, how about something more like Harper from Andromeda? A network jack of some kind in one's neck, and thus a direct link in to appropriately configured equipment.
And on that note, while I'd find it immensely cool and useful to be able to access, manipulate, and process data via a direct cable feed, I'd hate to have a wireless connection. Imagine being able to drive-by hack somebody's head? Talk about the privacy issues with that...
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