Say What?

Among my favorite things to read are bumper stickers. Along with T-shirts and baseball caps, they are a venue that encourages profligate free speech. But for some people, even ordinary bumper stickers don't provide enough opportunity for full expression of what they believe. Apparently, that was the case for whoever used the entire tailgate of this pickup truck I spotted yesterday outside of Costco as a billboard to let the world know what he was thinking. The only problem is that I have no idea what the author is trying to say. I think it may be a statement against littering in outer space, but if anyone has a clearer interpretation, I would love to hear it.