If i was a scientist at NASA discussing the Face with someone who thinks it was created by aliens i would tell them that it was a huge rock formation giving the illusion of eyes, nose, and mouth. I would also say to them that Micheal Malin and his Mars Orbiter Camera team snapped a picture ten times sharper than the original Viking photos which can prove that i was just a landform.

Thousands of anxious web surfers were waiting when the image first appeared on a JPL web site, revealing. . . a natural landorm. And to add to the conversation i would tell them that the picture actually shows is the Martian equivalent of a butte or mesa-- landforms common around the American West.

Then tell them how can aliens create a landform.

In conclusion, I would show them pictures of the landform on the monitor then zoom in and prove to them that its just a landform with an illusion. Then after telling them this information they should understand why its just a landform with and illusion but aliens did NOT make the landform