UPDATE: Setback for Russia's GLONASS System

UPDATE: This is updated with further details from RIA Novosti.

Russia’s GLONASS navigation satellite system suffered a setback today when three satellites were lost in a failure of their Proton launch vehicle.

The GLONASS satellites are launched in groups of three. What caused the Proton to fail is under investigation, but Russia’s Itar-TASS news agency quoted an unnamed Russian aerospace industry official as saying “The rocket’s engine gave a much bigger impetus than planned, and the orbiting unit separated at an altitude much higher than the designated one.”

The Voice of Russia website downplayed the effect of the loss on the satellite system, which is conceptually analogous to the U.S. Global Positioning System (GPS). Like GPS, 24 operational satellites are needed for a fully functioning system. For many years, Russia could not maintain that number, but it recently became a governmental priority. Although Voice of Russia reports that there are 26 GLONASS satellites in orbit including “two in reserve,” Aviation Week points out that “two are spares and the other four are not operational.” Thus the constellation is still short of the 24 needed for global, three-dimensional coverage.

Russian news agency RIA Novosti added that the satellites fell into the Pacific Ocean 15,000 kilometers north of Honolulu. That news source says that three of the on-orbit GLONASS satellites are not functional, rather than four as reported by Aviation Week. It does confirm that the three lost today were intended to complete the operational network.