Objects on the surface of Mars that resemble pyramids, a human face, and a city. To some, they suggest that Mars is or has been at some time inhabited. During the 1960s and 1970s, a series of U.S. space probes took thousands of pictures of Mars, all indicating that there was no life on the planet. However, the two photo analysts Vincent DiPietro and Gregory Molenaar of Goddard Space Flight Center in Maryland came across what appeared to be a cluster of pyramids and several other structures. Although NASA attributed the images to optical illusion, DiPietro, Molenaar, and others began to search the Viking photos for more evidence of artificially created structures. Science writer Richard Hoagland promoted the idea that civilized beings had either lived on or visited Mars long enough to build these fantastic monuments. In Monuments of Mars, he included the results of experiments by an electrical engineer and image-processing expert, Mark M. Carlotto, who enhanced the images. Carlotto believes his enhancements, which gave hints of roadways and entrances to the structures, prove that the structures are artificial. Not everyone is convinced, however. NASA continues to deny that anything except natural structures were found on Mars.
More recently, Hoagland claims to have found evidence of artificial structures on the moon as well. He and his colleagues continue to urge NASA to explore Mars more fully, preferably with a manned landing party, to discover once and for all whether the monuments are artificial or natural.