Some opinions have shifted
"If you believe, they put a man on the moon..." --REM, "Man on the Moon"
Some people suggest that space exploration is best done by robots, not people. They say that robots can do everything that people can do, in terms of research, so sending people into space is an unnecessary risk. This is not an unnecessary risk--Astronauts know the risks, yet they do it anyway, space exploration by people makes a sense of wonder, nations can cooperate instead of fighting each other, and people can get a better general idea of the big picture than robots can.
It's true that putting people on top of an extremely powerful rocket, then proceeding to accelerate them very fast, and send them into space, is risky. Sending robots instead of people would eliminate the risk that one of the astronauts could die.
Astronauts are very smart people, and they know the risks. They know that one small error--which could have been made months before the actual launch--could be the difference between living and dying. They know that astronauts in the past have died. Yet they still take the risk and go to the International Space Station.
This is because it's different to see pictures of space, than it would be to actually be there.
It's like travelling to Europe for the first time--You get there and then go on a walking tour, and see the cobblestone streets and place that i believe is called a courtyard, and onion shaped churches, and a building where Hitler would give his speeches (from the second floor balcony, where nobody is allowed to give a speech from now.) And you think "Wow, I'm in Europe!"
For astronauts it must be the same thing--to actually be there. To see the Earth from outside looking in, for a change. They take the risk because of a sense of wonder.
Unfortunately for the people who support space exploration only by robots, it also does not create very much of a sense of wonder in the average person, to see on the news "Mars rover thingamabob discovers more chemical compounds on Mars!" But people travelling in space captures the imagination.
Space exploration in general, promotes cooperation between countries. They have the International space station, and what better way to avoid war than to work together on a project that involves some of the smartest, and most skilled people (in terms of science and engineering) in the world.
Finally, although robots are extremely advanced, it is people who can look around them and immediately get a general impression of what it is like there. Robots would not be able to tell if people would get depressed by staying on Mars for extended periods of time, but people could arrive there and say "Ugh this place is so depressing." Of course it will be a long time before people land on Mars, but they should try to strive for it. If they can make technologies to kill people, they can make technologies to protect people from the radiation they would be exposed to in long periods in space.
Sending people into space is not an unnecessary risk, because space exploration by people creates a sense of wonder, cooperation between nations, and even a more general picture of what living on another planet would be like.
EDIT: February 4, 2008. This morning in the physics lab, the lab instructor got everyone who was planning on doing the next course next year to raise their hands (to get a rough idea if they would need one lab or two, etc). Then she said they were planning on getting a robotics course, and would anyone be interested in that. Zip. Nobody. (Well nobody's sure yet).
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The balloons weren't red, in the original version of "99 red balloons" by Nena. They were 99 Luftballoons--which is german for 99 balloons. I guess the "red" was an "arbitrarily" chosen colour chosen by some person back in the day, someone who didn't like communism?