Russia today successfully launched a military payload on a Soyuz rocket, ending a year long gap in such launches due to the discovery of faulty and corrupt practices at rocket engine manufacturing facilities.

The lull in activity has in part been down to manufacturing defects and quality control issues affecting Russia’s production of rocket engines. A contractor was found to have been using cheaper materials in place of precious metals in alloys used to make parts of the engines. Seventy-one Proton engines and a number of Soyuz engines were recalled for inspection and repair.

Reliability concerns have lingered around Russia’s launch fleet in recent years, with Proton failing ten times since 2007 and Soyuz experiencing seven failures in the last eight years. Two Rokots and a Zenit have also failed in the last decade, while Russia’s flagship Fobos-Grunt mission to Mars never left low Earth orbit after the spacecraft itself malfunctioned.

In 2016, Russia experienced just one launch failure – with a Soyuz-U rocket suffering a third stage failure during December’s attempted launch of the Progress MS-04 vehicle to resupply the International Space Station. Despite this, there were two near-misses: a Soyuz-2-1b underperformed during the launch of a GLONASS navigation satellite last May, and the Proton launch in June suffered a second stage engine failure. In both cases the rockets’ upper stages – Fregat-M and Briz-M respectively – were able to alter their flight plans and inject the satellites into their planned orbits despite the anomalies.

They hope to resume Proton flights next month. Either way, it looks likely that in 2017 Russia will launch the fewest rockets in decades.