text: "As a rule of thumb, you can discern thinkgs in a digital image 3 times bigger than the pixel size". In egyptia-style prramids or even small shacks, you could see what they were! There must have been a degree of surprise among mission controllers back at the Jet Proupulsion Lab when the face apperared on their moniters. NASA, a few days later, unveiled the image for all to see. The authors thought it would be a good way to engage the public and attract attention to Mars.