MOSCOW, March 23 (Xinhua) -- Russia plans to launch a Glonass-M navigation satellite into orbit in mid-May, local media reported Saturday.

"The launch of a Glonass-M navigation satellite has been tentatively planned in mid-May from the Plesetsk Cosmodrome for maintaining the performance of the orbital constellation," Sputnik news agency quoted a source in the aerospace industry as saying.

Currently, the Glonass constellation includes 26 satellites with 22 of them performing their intended navigation functions. However, the system needs 24 satellites to be operational to ensure global coverage, said the source.

At present, 16 out of 26 satellites of the constellation have expired, according to the source.

Glonass is a global navigation system operated by the Russian Aerospace Forces for both military and civilian use.

It is a Russian equivalent to the U.S. Global Positioning System and China's BeiDou navigation system, providing real-time positioning and speed data for land, sea and airborne receivers worldwide.