My Left Ear, My Right Ear.....

"Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun.
Orbiting this at a disctance of roughly ninety-two million miles is an utterly insignificant little blue-green planet whose ape-descende life-forms are so amazingly primitve that they still think digital watches are a pretty neat idea."

A certain 'forty2' has picked me up below for my pessimism. Moi? Nahhhh..... But I must say I object to the word "needless". The rest of the world would be in dire trouble were it not for the likes of me. If we were not thinking of a million ways something could go wrong, you optimistic people wouldn't have the luxury of saying how unlikely it is that any of them will happen. We are a valuable check and balance I'll have you know. We say "I can envision a future where pop star managers create a line of clones with ten year age gaps in order to have continuity over 100 years." (You laugh- Madonna says 'new image', I say Version 6.0. It's like the evolution of car design in reverse, every time the it gets more boxy...) And respected important medical ethics people boff and waffle and then go and draw up legislation to make sure something a tenth as silly never happens just to be on the safe side.
Now that we're done on pessimistic silliness, lets talk about the current optimism about going to Mars. Why go to Mars? They're sending another probe up today which should tell us far more about the surface of the planet, possible existence or previous existence of water and so on. Sounds good. It's an orbiter too, so there's less chance of them losing it. That's the thing, so far we haven't managed to get an unmanned rover down on Mars with anything like a decent strike rate, let alone send and retrieve an unmanned craft. But scientists (let's hear it for the "what happens when....?" brigade) seemingly want samples from Mars. These would tell them what bits of Mars look like, feel like, smell like, and crucially if they're like other bits of rock they've got. Now the way I see it, you have two options. You can either try to make better unmanned craft, something that detatches itself from and returns to a re-launchable craft and is operated by glorified remote control. This will doubtless be very expensive, and probably wouldn't work the first couple of times. Or you can throw everything behind a manned mission to Mars, requiring all sorts of new technology. This will doubtless be very expensive, and might not work the first times. The major difference is what doesn't come back.
Accepting the darn thing gets off the launchpad and into space without blowing up or sloughing off its skin, what would the journey to Mars be like? www.space.com Says "on long missions, what would otherwise be minor threats could become at best serious limitations or at worst deadly disasters." They list:

Lack of a medical facility could turn a mundane injury into a life-threatening situation;
"Psychosocial" pressure will be high in a small group isolated for months or years;
Zero or reduced gravity causes bone and muscle loss;
Dangerous radiation particles are abundant beyond Earth orbit.

Discounting the psychological angle on the basis that anyone prepared to go on this mission is clearly insane already, consider the interaction of the other three. Weakened physically by the effects of reduced gravity, and assaulted by radiation, the astronauts will be more vulnerable to injury and illness, including serious illnesses like cancer. A likely minimum of two and a half years for a mission means that the astronauts will be without the sort of routine medical monitoring and treatment that we take for granted, such as dentistry, proper diagnosis of and prescription of appropriate antibiotics for such things as ear infections. Imagine having an untreated dental abscess for 18 months. And what if one of the astronauts developed cancer from the radiation?
Space.com says "Any trip beyond Earth orbit will involve radiation threats not faced by residents of the International Space Station, which sits inside the planet's magnetic field."
Assuming we've got people all the way to Mars and they're not dead or too weakened from muscle loss, radiation and untreated minor ailments to walk at all, let alone in an extra tough space suit on rocky ground, they'll have to survive 18 months parked on the planet waiting for the earth and Mars to align correctly for the return journey. And another two years if they miss that one far any reason. While on Mars, as well as the radiation, there are basically unknown weather conditions, the attendant hazard of equipment failure as there is no was of testing the new technology in the environment it will be exposed to, so they'll find out if it works if it works. Oh and solar flares.
Back in the days of one small step for man "Mission planners knew the Apollo astronauts would be at grave risk if a strong solar flare occurred during a mission. The short duration of each trip was a key to creating favorable odds." Even between here and the moon "A big solar event during one of those missions could have been catastrophic... The risk was known. They gambled a bit." Solar flares can damage spacecraft in flight, or cut communications with anything on Mars. Solar storms, massively increased levels of particles of radiation like the a cross between a sand storm and a nuclear explosion, may well even kill instantly. The chances of getting caught in one are increased by the fact that the astronauts will be required to roam all over the surface of the planet, and the fact that any warning sent from earth about increased solar activity would take between four and twenty one minutes to reach Mars.
And all the time one rip in a suit, one deteriorated seal, one tiny little hole in the habitat, and everybody dies. This is not a Class M planet.
And for what? We keep hearing scientists think Mars may one have been like earth, and hope it will hold clues to climate change etc etc. Clearly not. Either the two planets are similar, and we'll eventually lose some of our atmosphere and dry out and become barren rock, and there's nothing we can do about it. This will give scientists the clue that climate change is constant and happens regardless of what any life forms on the planet do. There is no evidence of a now dead civilization on mars, so clearly the planet did not go the way of the fossil fuels. Alternatively the planets turn out to be substantially different, and we find out that they're substantially different. Either way it fails entirely to matter.
We can't build there, we can't stay there, we quite possibly can't survive there at all. There is no point. You can forget the moon too. Closer, yes, but no atmosphere, so even more dangerous than Mars radiation wise. And as for space tourism, if there were as many shuttle flights as plane flights the accident rate means we would be losing over 250 passengers a week. With no possible proper crash investigation to tell us what went wrong as the wreckage would be dust in space.
So, yes, optimism. We are getting better and better at utilsing the space around our planet for communications satellites, we are getting better at building probes and telescopes to see incredibly far into space. We are getting better at robotics. We can find out so much without risking lives. If there is intelligent life out there, we are more likely to find it and less likely to accidentally start a war with it if we are talking in terms of radio signals than if we rock up on some planet giving it "Hello, are you the people of Gaul? Well we're the Roman army, and this is our leader, Mr.Dog." We should revel in what we can achieve and look forward to better telescopes, robots that can be sent and bought back from the surfaces of other planets, scanners that can give us geological data on planets light years away.
We can't be trusted with space. Commercial companies who want to be allowed to pop up and play are suggesting orbiting rubbish heaps, orbiting 'graveyards' of coffins (presumably ones that can steer round satellites), and giant advertising signs that can be seen from earth. It's be the first time in decades anyone in London could look up in the night sky and see 'Mars'. But why stop there? Why not giant screens so the Bushmen of the Kalahari can watch Big Brother? Of course big powerful men are attracted to space, not because it's the last uncrossed barrier, but because it's the last place where the whoever gets in there first can take possession of and do whatever they like. If NASA fucks up much more often the Americans will get tired of paying for it and either allow private companies to go up on trust (cos it'll be a bit hard to stop anyone doing anything once they're up there) or integrate it into the Intelligence agencies and we wont have a scoob what they're up to. It will be a lawless fight for whatever can be exploited, the Wild Western Spiral Arm of the Galaxy. The final fronteer.
Front Ear.... geddit?