Team member David Mencin crouches next to a white weather dome that protects a GPS unit.

Measuring the world’s tallest mountain is literally an uphill battle.

Veteran cartographer Bradford Washburn is leading a team of scientists, climbers, and Sherpas in an effort to determine the height of Mount Everest and assess whether the fabled, fatal peak is growing taller. Spring 1999 marks the third of three arduous seasons in the field.

The current figure—29,028 feet (8,848 meters)—was determined by the Survey of India in 1954 and verified by NATIONAL GEOGRAPHIC magazine for its November 1988 issue. But that measurement may not survive the most painstaking scrutiny yet.

THE KEY: GPS SATELLITES

The global positioning system (GPS) makes it all possible. Ten thousand miles (16,000 kilometers) above the Earth’s surface, this man-made constellation of 24 satellites orbits the planet twice each day. The array can locate any point on the planet.

But getting a GPS unit atop Everest once seemed impossible. “In the early nineties, a GPS weighed 50 pounds [23 kilograms]. Now you can hold one in your hand,” says David Mencin, who will be at Base Camp monitoring the GPS data.

Using handheld Trimble GPS units, the Millennium Expedition will collect data from 12 satellites. (Most small units, in contrast, only access 5 satellites.) In the past two years, the team has collected GPS readings from various points on Everest. This May they will cap their research with data from the summit.

Scientists will then compare the summit GPS reading to those from other points. Much number-crunching later, they hope to unveil the most exacting Everest measurements yet.

SNOW AND STATISTICS

“The summit of Everest is basically a snow dump,” says Dr. Mike Jackson, GPS specialist for the team. Storms bury the summit, then high winds sweep the snow away.

To make sure they’re measuring the true summit, the Millennium Expedition team will use a snow-penetrating radar device much like a metal detector at the beach. Because the radar was too heavy for climbers to carry last year, experts at the Massachusetts Institute of Technology designed a lighter device for the 1999 season.

Thus the Millennium Expedition will take measurements it was never before possible to obtain.

IS EVEREST GROWING?

The continent of Eurasia is perpetually colliding with the subcontinent of India. Their clash forces the Himalaya upward. How does this tectonic drama affect the height of Everest?

In its search for the answer, the team will take a GPS reading from the South Col, a plateau of ice and boulders about 3,000 feet (915 meters) from the summit. Because that spot has been monitored for years, the scientists will be able to determine whether Everest is growing taller.