Very cool idea; a couple of thoughts. Given that the ship is coming toward the "parent" perhaps "Hello my son" might work better, or you could get really creative and manipulate the image so that the ship is moving away from him. I agree that the monochrome needs a little more work. I'd like to see the face of the person. In fact, I think that this idea should be taken to the next level; set it up as a posed shoot, have the person show some emotion (sadness/joy depending on whether it's hello/goodbye) and really nail the technical side.