I remember reading a story about humans colonizing Mars. It was from the point of view of a pilot and I think he and others were mining asteroids to use the materials on Mars. I do remember they used water vapor for thrusters.
Someone on Earth was using the Mars colonists as scapegoats and behaving like the Late Senator McCarthy. He kept referring to them as "Water wasters" and said they were demanding water from Earth and would use up all the water and humans would have to ration water and so on. In truth, the amount of water they were using (I think from Martian polar caps) was quite small and they were no threat -- the politician was just using them as a focus so he could build his career.
Rather than take him on politically, they sent an expedition out to Saturn, grabbed a large chunk of ice from Saturn's rings, brought it back, and I think they crashed it on Mars, talking about how it would serve their needs for decades or more.
I can't remember if there was more, such as figuring that one effect of that much water on Mars (as it changed into liquid form) would help with terraforming or not. But I remember the point was that they could not longer be used as a scapegoat by the politician.
The recent talk of asteroid mining has me thinking of this, but I can't remember the author's name or the title.