What are the advantages and disadvantages of space travel/ space stations on humanity and the environment?

please give as many reasons as possible

the advantages are that we get to explore plants and things we couldn't before. one major disadvantage is the amount of resources it takes to travel into space.

Although our space technology is not yet nearly good enough, in the future Earth will get substantial resources from space because there are not enough resources on one small planet for such a large and wealthy population.

well, I can see people point in listing all the disadvantages. But, the real advantage of it outweighs them all in my opinion. Sooner or later I believe our planet will face disaster unimaginable. According to Nastrodamus it will be in 2012, And if the human race is to survive.....that doesnt give us alot of time to colonize space, then hopefully a new planet.

Well, in the ultimate scope, we'll outgrow this planet at some point. There is an upper bound on how much food this planet can produce, and a lower bound on what one individual needs in order to survive, to say nothing of maintaining any sort of standard of living. If we want to be able to all have families and comfortable lives, we will need to leave Earth and find more resources and space.

Most of our efforts in manned space flight today are geared towards understanding how to survive in space long term. This is necessary if we're to ever go further than the Moon. What effect does weightlessness have on your body? How do you treat disease in space? How do you deal with emergencies like fire and environmental system malfunction?

The only way to find out for sure is to go do it. They're finding that lab animals born in space (for instance) can't survive well back on Earth. This means that zero-g pregnancy is a big no-no. Not only do we think it would be bad - we have an example of the results. Experiments like this are what we're using the ISS for. Long term space habitability practice. Why is this important? See first paragraph.

Disadvantages are many as well. Obviously, the danger factor is very high. Space travel requires vast amounts of energy and machinery that must operate in extreme conditions routinely. Only a thin thread holds an astronaut from death - if anything vital fails, that's all she wrote. Apollo 13 is an example of just how tenuous survival in space is. Of course, it's also an example of human will and ingenuity to overcome challenges.

Space travel requires huge amounts of energy. One loaded space shuttle at low earth orbit represents enough energy to power a neighborhood for days! If you think there's an energy shortage now, imagine once everyone is trying to get into space!

Space travel is expensive. This is only a relative item in my estimation, because I feel that we get a bounteous return on our investment. We get priceless knowledge about the universe and how it works, as well as all-important experience in making our way to the stars.

We're still a long way from becoming a star-faring race, but if we don't work towards the goal, it will never be achieved.

Anything that fires and inspires the imagination, courage and hope for human beings is an advantage. Without stacking a lot of what's hoped for atop what's actually known, probably any other advantages are microscopic. But the former pays the price of admission many times over.

I don't see a single disadvantage, but that's based entirely on my personal value system.

You can make things in the zero gravity of space that you can't on earth.

You can observe the earth in a way you can't from the surface. The human eye is more sensitive to subtle differences in color than the most sophisticated instruments, so having people up there can alert us down here to changes we may not be able to detect.

Space is an energy-rich environment. One day we might have the capacity to capture enough of the sun's energy from space to abandon using fossil fuels.

The main disadvantage is cost.

For humanity, the advantage would be more jobs, more advances in science, and a sense of accomplishment as we explore and settle more areas in outer space.
For the environment, it means we will rely less on Earth's resources. We'll be able to mine asteroids and other sources of natural minerals off Earth and also we'll be using solar power more. I think of it as being like rolling a pebble down a mountain, the effect will build on itself once we get it started.