Molniya-M

The Molniya-M (Молния, meaning "lightning"), designation 8K78M, was a Russian (previously Soviet) carrier rocket derived from the R-7 Semyorka ICBM. Chiefly designed to correct design deficiencies in the third stage of the 8K78 booster, it was first launched in 1964 and had replaced its predecessor, Molniya, by the end of 1965. During 1967, the improved core stage and strap-ons from the Soyuz 11A57 were adopted and made standard on all R-7 based vehicles. It made 297 launches and experienced 21 failures, the last of which occurred on 21 June 2005 when a third stage malfunction prevented its payload, a Molniya-3K communications satellite from reaching orbit. The final flight of a Molniya-M was conducted on 30 September 2010. It will be replaced by the Soyuz-2/Fregat.

For most of its operational life, the Molniya-M was used to launch its namesake Molniya and also Oko satellites into Molniya orbits, orbits of high eccentricity that allow satellites to dwell over polar regions.

Variants
There were four main variants of the Molniya-M, which varied in terms of their upper stage. Originally, the Block L stage was used, however uprated versions replaced this with more powerful, or specialised, stages, for different missions. The Molniya-M/2BL, used to launch Oko missile defence spacecraft, had a Block 2BL upper stage, The Molniya-M/ML had a Block ML upper stage, and the Molniya-M/SO-L had a Block SO-L stage.

Retirement
The Molniya-M/ML was scheduled to be the last variant to fly, with two launches of Molniya spacecraft scheduled to occur in 2008, however they were cancelled in light of the launch failure in 2005, in favour of the Meridian spacecraft. The Molniya-M was believed to have been retired on 23 October 2007 after launching an Oko spacecraft, however this later proved to have been incorrect, when a Molniya-M was used to launch another Oko satellite on 2 December 2008. Following a launch on 30 September 2010, the Russian Space Forces confirmed that it had been retired from service.