It’s quite a feeling when a dream finally comes true. After two years of talking, planning, begging for help, watching volunteers put in long hours, the ImagineU Children’s Museum will open on Saturday. Children can go on to the Mars Yard, which got its finishing touches last weekend with the help of architect Dana Berry (also president of the museum board), builder Andy Anderson and volunteers Ben Owen, Daniel Reyna and Mark Koenig. They used Styrofoam, chicken wire and cement to create an authentic-looking Mars surface where children can steer remote-controlled rovers. Eventually, there will be a computer center where young astronauts can control the spacecraft.