This was in fact first launch of the rocket from Russia in 2017 not related with International Space Station. Mission was planned to cover demand of Russian Ministry of Defense for delivering to orbit another EKS satellite, which will operate as part of the Early Warning System against rocket missiles. EKS stands for Edinaya Kosmicheskaya Sistema (Unified Space System) and was planned to rely on on six satellites called Tundra. EKS was designed as a replacement for outdated OKO system remaining in service since 1972.
Due the classified character of this mission, Roscosmos did not provide live coverage. Soyuz started from Launch Complex 43/4 at Plesetsk Cosmodrome at 06:34 UTC. Plesetsk placed 500 km to north from Moscow is often used for launching classified military payloads. Rocket with Fregat-M upper stage should reach GTO orbit to deploy satellite to make possible reaching GEO orbit with altitude of 38500 km x 1626 km inclined at 63.37º. It will be second Tundra class satellite after first launched in 2015 on November 17 (Kosmos-2510) and will enter the service under “Kosmos-2518” codename.
Each EKS satellite is manufactured by RKK Energia with utilization of USP bus – lightweight and relatively simple in design, without pressurized compartment for payload. Satellite weighs around 1200 kg. Payload is provided by TsNII Kometa; satellite is powered by two deployable solar arrays which can generate 2200 W of power to charge Nickel-Hydrogen onboard batteries. USP is equipped in three axis attitude control relying on star tracker, sensors and utilizes reaction wheels to keep satellite on correct orbit. Manufacturer has not announced any specification of the payload, but analogical satellites are usually equipped in IR telescopes and other optical instruments for tracking flying missiles. Russia plans to deliver to orbit last from six satellites in 2020.
Soyuz-2.1b was developed in the early 2000s as improved version of Soyuz-2.1a for lifting large payload covered with ST fairing. Its construction is based on four boosters, two core stages and upper stage. Each booster is powered with single RD-107A with thrust at 838.5 kN, which burns 44413 kg of propellant (RG1/LOX). First core stage is powered by one RD-108A with thrust at 792.5 kN and fueled with 90100 kg of propellant (RG1/LOX). Third stage (boosters are considered as first stage in spite of fact that they start in this same moment as core stage) is equipped in one RD-0124 providing thrust at 297.9 kN with fuel reserve of 25400 kg of RG1/LOX. Fregat upper stage weighs 902 kg and takes 6638 kg of NTO/UDMH propellant. Its propulsion is single S5.92 engine which provides 19.85 kN of thrust. It is able to perform up to 20 burns and is equipped with independent guidance, navigation, attitude control, tracking and telemetry systems.