This may be the most expensive penis graffiti in the history of humanity. NASA’s twin exploration rovers Spirit and Opportunity accidentally drew what appears to be a large phallus during their 10km-plus exploration on the surface of Mars. The discovery was first made yesterday by Redditor radioactive_toy in a post submitted to the /r/pics subreddit, which quickly reached the frontpage and temporarily brought down the NASA web server as a result of the “Reddit Effect.”