How a one-of-a-kind robot led researchers deep into the Great Pyramid

In the heart of the Great Pyramid of Giza, in a room called the Queen’s Chamber, a mysterious shaft not much wider than a dachshund leads diagonally up and into darkness. 

It was discovered by a British engineer in 1872, together with a similar passage on the room’s opposite side. Both these southern and northern shafts had been bricked over, and neither seemed to extend all the way through the pyramid, as there were no openings on the outside. So where did the shafts lead? And how to explore them? The questions persisted for more than a century.

In 2002, National Geographic TV producers plumbed the southern shaft using the Pyramid Rover, a scissoring Swiss Army knife of a robo-crawler, with treads to grip both floor and ceiling. Its engineers, from the company iRobot, arrived in Giza that summer toting a dozen-plus cases of parts, along with piles of scrap aluminum and a milling machine, for making modifications on the fly. When sections of the shaft proved too uneven for the rover to traverse, the team designed and attached a mechanism to deploy small ramps. When a limestone slab halted the robot’s progress about 210 feet up the shaft, the engineers equipped it with a drill to bore a narrow, exploratory hole.

The mission was patient and iterative, with ever deeper journeys into the passageway punctuated by upgrades. “We set up the milling machine at the hotel room on the patio,” remembers former iRobot engineer Christian Weagle, who traveled to Egypt for the project. “And every other night we would just make new parts.” 

In September, after weeks of probing, the rover made another trip to the end of the shaft, this time equipped with a fiber-optic camera. Gently, the operators snaked it into the hole they’d drilled, revealing a small chamber to a TV audience watching live. The space was empty, the shaft’s purpose as mysterious as ever. Along the way, though, the rover did record something extraordinary: masons’ marks in red ocher dating back to the pyramid’s construction. 

“We were the first people in 4,500 years to see those red pigments,” says Weagle, who remembers his sense of awe. The ancient marks, he says, felt like a link to the original builders—evidence of minds thinking through tremendous challenges.