Luch 5B (Russian: Луч-5Б meaning ray and sometimes transliterated as Loutch-5B) is a Russian Luch relay satellite which transmits data from the Russian Orbital Segment of the International Space Station, and from other satellites in low Earth orbit.

[2] They are dual purpose satellites with both military and civil uses, and are similar to those in the US Tracking and Data Relay Satellite System.

[3] Luch 5B was built by JSC Information Satellite Systems using the Ekspress-1000A bus.

[2][4][5][6][7][8] The satellite is designed to relay data from the ISS, satellites in low earth orbit and rocket launch vehicles.

It was launched from Baikonur Cosmodrome launchpad 81/24 by a Proton-M rocket with a Briz-M upper stage.