On June 8, 1924, George Mallory and Andrew Irvine left their camp less than a kilometer from the summit of Mount Everest on a mission to be the first mountaineers to ascend the world's highest peak (8,850 meters). They were never to be heard from again. Whether either man reached the summit—almost three decades before Sir Edmund Hillary and Tenzing Norgay's historic 1953 climb—has been an open question for nearly 86 years.

Although more than half a dozen expeditions have gone to Everest in subsequent years to determine the outcome of Mallory and Irvine's expedition (a 1999 search turned up Mallory's body), none have returned with definitive answers. The key to solving the mystery, many climbers say, is finding Irvine's remains and with it the missing Vest Pocket Kodak (VPK) camera he was supposedly carrying with him on that fateful journey.

Everest historian Tom Holzel believes that after decades scrutinizing maps and photos of Everest's north face, where the mountaineers are thought to have disappeared, he may have spotted Irvine's final resting place in a high-resolution picture earlier this month. Holzel has begun mounting an expedition he hopes will visit the site either this spring or, more likely, spring 2011.

Old mystery versus modern technology
Holzel put together a 1986 search for Mallory and Irvine that was thwarted by a heavy snow. Now, he and a group of five colleagues (who together have formed the Andrew Irvine Search Committee) say their study of a set of aerial photographs of a 900-meter-wide area of the mountain's north face known as the yellow band has turned up an anomaly on the terrain that is roughly 1.8 meters long and positioned in a manner consistent with a description relayed by a Chinese climber who claimed to have spotted the body of an Englishman up on the mountain in 1960.

The anomaly, which Holzel refers to as an "oblong blob," revealed itself only after a series of experiments that began with the researchers using a computer to morph together two images—a photo taken within the yellow band in 1933 by climber Wynn Harris and a high-resolution aerial image taken of the north face from a SwissPhoto, AG, Learjet in December 1984 at an altitude of 13,500 meters. The latter photo is notable because it is an orthophotographic image, one that is geometrically corrected so that it is an accurate representation of Earth's surface and can be used to measure true distances.

Harris took his photo during a search for the missing climbers. On this photo, he marked an "x" where he found an ice ax thought to have belonged to Irvine. Researchers speculate that the "x" marks the point of a slip by Irvine and Mallory and could provide some clue as to where Irvine's body is located. By comparing Harris's photo with the aerial image taken by SwissPhoto, Holzel determined that the presumed location of the ice ax was incorrect by some 55 meters.

Renewed hope
Bolstered by this discovery, Holzel and two other committee members chipped in to buy a powerful microscope and digital camera they could use to scrutinize the aerial images in fine detail. Holzel used the microscope and camera to take sequential digital microphotographs of the aerial photo at 60 times its normal resolution. Then he used software to compile those microphotographs into a high-resolution color digital panoramic view of the yellow band.

When printed, the panoramic view revealed the likely descent route that Mallory and Irvine (and the Chinese climber in 1960) must have taken. The researchers knew that the panorama's resolution was not high enough to show a recognizable human body, so once the likely route was determined, they used the microscope to look for body-size anomalies in an area consistent with Mallory and Irvine's probable descent route. "Based upon what happened, the body could only be in a certain number of places," Holzel says. "The panoramic view enabled us to figure out where he could have gone down."

Irvine's final resting place?
Holzel came across what he refers to as a "red slash"—a long diagonal slot—alongside a route where Irvine's body was said to have been spotted. Although the slash is estimated to be about one meter wide by six meters long (too long to be a 1.8-meter body) and is more likely a sharp-walled gully or crevasse, further scrutiny revealed an image within the slash that is roughly the size of a person. "The 1.8-meter blob appeared to me [in early January] just as I was about to write the committee to say that we seemed to have struck out," Holzel says.

The researchers confirmed the presence of this slash (and the object within it) with the help of a second north face image, this one a highly detailed black-and-white print of a portion of the yellow band, scanned by SwissPhoto using a five-micron laser. The location and orientation of the image in the black-and-white scan are also consistent with the testimony of the Chinese climber in 1960.

Searching the yellow band
Of course, much of the yellow band has already been canvassed by other searchers with little to show for their efforts. Snow cover is the big wild card when analyzing images of the north face, says Eric Simonson, the professional mountain guide who led the 1999 expedition that uncovered Mallory's body. Although the 1984 images are good, they cannot account for changes to the region made by yearly or even seasonal snowfall, he adds.

If Irvine is going to be found, it will likely be within the yellow band, Simonson acknowledges. "But it's a big area," he says. "Two of our guys spent a day in 2004 searching the yellow band, but there was too much snow to see. To be successful you have to be in the right place and be there when the conditions are pretty good."

If there is heavy snowfall in the area where Holzel wants to search, his team will likely require a metal detector, although this method has not proved highly effective because searchers themselves use metal axes and crampons that interfere with a detector's readings. As a result, Simonson says, "You have to be pretty close to an item to find it."

Simonson gives Holzel credit for finding creative ways to search for Irvine. "What Tom sees might very well be a body," Simonson says, adding, "but it might not be Irvine's body." An estimated 120 corpses still remain on Everest.

Unfinished business
Even Holzel admits that, "while the photographic evidence is evocative, it is not by itself fully convincing in terms of the exact spot Irvine lies." He is hoping to put together a small search team of two Americans and two Sherpas to investigate his finding, a sojourn he expects will cost at least $125,000 and hopes to mount in the coming months or next year. "The only way to prove it is to actually go there," he adds. Holzel has even written out an extensive list of procedures regarding how to properly handle the camera and develop the film if they are found intact.

Although finding Irvine without his camera (or finding a camera that is too badly damaged to produce pictures) would shed little light on whether he and Mallory succeeded, "we have good reason to think that [Irvine] had a camera," Simonson says. "That's why we went back in 2001, to find the camera." (Howard Somervell, who was part of the 1924 expedition, has been quoted as saying that he had loaned his Kodak VPK camera to Mallory as they passed each other on the north ridge.)

"It will be a momentous day if that camera is found," Simonson concludes, a day that could change history.