Lots of people have thought of similar things. I know I have read scifi which uses water for shielding but I can't think of a specific name. However, water isn

Lots of people have thought of similar things. I know I have read scifi which uses water for shielding but I can't think of a specific name. However, water isn't light. According to this post on stack exchange it would take something like 330,000kg of water to shield a crew. Getting that into orbit is a big task.