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Daniel Irwin and William Saturno
NASA scientist Daniel Irwin, left, and archaeologist William Saturno, explore a trench below an ancient Mayan pyramid in Guatemala.
Tom Sever and Rob Griffin
Deep in the Guatemalan jungle, NASA archaeologist Tom Sever, right, and Rob Griffin, a graduate student at Pennsylvania State University in College Park, Pa., study a crumbled "stele," a stone pyramid used by the Maya to record information or display ornately carved art.
Spotting ancient Mayan ruins--a challenge even on the ground--has been virtually impossible from the sky, where the dense Central American rain forest canopy hides all but a few majestic relics of this mysterious civilization.