If you click through the second image, you'll see the placard from the Rose Center for Earth and Space describing this photograph from the Apollo 17 mission:
"The Sculptured Hills appear in the center background, and the flank of South Masif looms at right. A discarded plastic rock sample bag lies alongside Apollo's final footprints."
What a strange choice of words. I'm reminded again of a passage from Bruce Sterling's Shaping Things (PDF):
If we were to judge ourselves by the efforts of ours that survive the passage of time, we'd be best described as Man The Rubbish Maker . We've been polluting since before we were human. Chipping rocks into tools is a messy, haphazard process. When archeologists investigate ancient rock foundries, they always find vastly more rock waste than they ever find tools. Rock waste is the earliest form of pollution.
As you might imagine, there are a number of people actively debating the complicated ethical questions surrounding how to approach our exploration of extraterrestrial environments. (see: Martin Rees, Life's Future in the Cosmos)
