Bug/Issue Ore detector skipping covered background blocks

I'm not sure if this is a bug or the intended operation of the ore detector; if it is a bug, then it's a minor one, but still slightly annoying. If ore is in the background and are covered by foreground blocks, the ore detector wont register them as being there. When mining asteroids, I had to resort to making branching tunnels through rock to make sure I wasn't missing large patches of ore.