The satellites were the last of the batch of 24 satellites at the heart of Glonass, Russia’s answer to the U.S. Global Positioning System.
As of December 5 the Glonass constellation was made up of 26 satellites, including 20 in operation, two on standby and four under maintenance. A minimum of18 operating satellites are necessary for Glonass coverage of Russia, and 24 satellites make the system global.
The crash of the Proton rocket is therefore a step back for a reliable Glonass global coverage; however, it does not threaten coverage over the Russian Federation.