The ways we know that the face is just a natural land form and not something created by Aliens is because we have done real research on the Landform. Not only that but when we took the pictures we used our cameras absolute maximum resolution so it would be as clear as possible. Plus the evidence has changed. Each pixel in the 2001 image spans 1.56 meters, compared to 43 meters per pixel in the best 1976 Viking photo. So we know that the planet is changing and thats how we know that the landform isn't created by Aliens. Plus we have a Surveyor which is a mapping spacecraft that normally looks straight down and scans the planet like a fax machine in narrow 2.5 km-wide strips. The number one way we know it is a land form and not something created by Aliens is because As a rule of thumb, you can discern things in a digital image 3 times bigger than the pixel size, he added. So, if there were objects in this picture like airplanes on the ground or Egyptian-style pyramids or even small shacks, you could see what they were!. Also we have pictures from 1976, 1998, and 2001 that shows its change and that it's a landform.