Steep Questions: How Tall is K2?

A Mountaineering Survey Team Determines K2’s Actual Height

Surveying the world’s highest peaks is a daunting task. One international survey team set out to measure the Himalaya’s K2 peak, the second highest in the world after Mount Everest.

In 2004, 50 years after an Italian team led by Ardito Desio first summited, a team tried to measure K2 with GNSS surveying equipment, but the attempt to bring the GNSS receiver to the top failed when a climber fell.

For the most recent attempt, a Pakasti-Italian team took along a rugged industrial survey system 60 years after the first summiting, in June–August 2014.

The team performed measurements at five different climbing campsites and on the K2 summit, using GNSS technology to collect the most accurate measurements ever made of K2.

The measurements were accomplished by Pakistan’s Rehmat Ullah Baigh and Italy’s Michele Cucchi, who set up the receiver at each stop and allowed it to remain for approximately 20 minutes to collect the latitude, longitude and altitude of each point from the available satellites.

Setting up camp also meant setting up a GNSS receiver to gather
data.

One reference receiver was permanently positioned by team technical leader Maurizio Gallo close to the K2 Base Camp at the Gilkey Puchot Memorial, which is dedicated to climbers who died on K2. A second reference receiver was placed in Skardu, a final stop before heading up the mountains. At Skardu, computer expert Fida Hassain from Central Karakorum National Park helped install and process the transmitted data along with researcher Aamir Asghar and Giorgio Poretti, professor at the University of Trieste. The coordinated network of two permanent GNSS stations allowed data from the summit to be processed with excellent precision and is still in operation today.

After the climb, the data was downloaded from the receivers and analyzed. The GNSS survey results lowered K2’s height from its previous altitude of 8,610.34 meters (28,248.03 feet) to 8,609.02 meters (28,244.75 feet) — 1.5 meters (3.3 feet) shorter than previously believed.

The route to K2’s summit.

Yet the biggest surprise was at K2’s Camp Four on the Abruzzi Spur, where expeditions on this route begin their final ascent to the summit. Previous measurements stated that the route began at 7,900 meters (25,920 feet). The new data collected proves that the route starts at 7,747.029 meters (25,416.667 feet), making the climb 150 meters (492 feet) longer than previously recorded. This is a challenging difference for K2 climbers, who at this point are struggling for weeks with the weakening effects of altitude sickness
and the stress of staying focused.

The team also plans to climb Mount Everest, where a reference station is located very close to the EVK2CNR’s Pyramid International Laboratory on the Nepali side of Mount Everest.

Manufacturer

The survey team used the Leica Viva GS14 GNSS receiver and two GX1230+ reference receivers and antennae provided by Leica Geosystems. Leica Geosystems used the opportunity to test its equipment’s portability, resistance to very low temperatures and rugged use on rough tracks.

Adapted from an article by Katherine Lehmuller and Marco Mozzon in the Reporter (#72), the Leica Geosystems customer magazine, and other sources.