Question: Why do scientists complain about the damage that we're doing to our planet but yet they continue to send probes and spaceships up into space adding poisonous gases etc into our atmosphere?

Jessica Housden answered on 16 Jun 2010:

Well, a space probe only emits as much fuel as two transatlantic flights. Now, I know that that isn’t great, but there really is a need for the ones that look at the Earth. Currently, we just don’t understand how our atmosphere works, and the only way to gather enough information is from Space. A spacecraft can orbit the Earth 16 times a day, and go over every single point on the Earth once a month. So, for two transatlantic flights (once they are in Space they don’t use carbon fuels), you can get information around the whole world. imagine trying to drive a car that distance ad the fuel that would use…
Then, there are the benefits to us. So, Sky TV, sending world cup football matches to us live, talking over long distances, GPS positioning. These are all only possible because of the spacecraft that we have sent up.
Another use is things like disaster monitoring – so, when the Asian Tsunami hit a satellite that we have sent up was able to take immediate measurements and photographs of the area to help emergency and aid workers go to the right places. In that sort of situation it would have taken many weeks to gather the same information without a spacecraft.
The ESA website is quite useful for more information, but I really am happy to answer any more, and I do understand your concern.