The Edinaya Kosmicheskaya Sistema (EKS), meaning Unified Space System, is a series of Russian early-warning satellites that can detect ballistic missile launches and link with Russia's system of early-warning radars to aid in Russian Federation defense in the event of nuclear attack.

The EKS series of satellites would also be instrumental in Russian missile defense and counterattack should the need ever arise.

Up to six EKS satellites have been ordered and to date, four EKS satellites have been launched.

EKS 1 Launched November 17th, 2015
EKS 2 Launched May 25th, 2017
EKS 3 Launched September 26, 2019
EKS 4 May 22nd, 2020

The EKS satellites are placed into Molniya orbits, highly elliptical, or oblong, orbits of 38,552 x 1,626 km inclined 63.37° to the equator.

The name of the orbit comes from the Molniya series of Soviet/Russian civilian communications satellites that first used these orbits beginning in the 1960s.

Meet part of Roscosmos’s 21st century version of the Soyuz rocket. 

One of the main upgrades included in the Soyuz 2.1b is a completely digital flight control system -- not a small task when the Soyuz rocket was first designed in the 1960s.

Stats

Height: 46.3 m (152 ft)

Diameter: 2.95 m (9 ft 8 in)

Mass: 312,000 kg (688,000 lb)

Stages: 2 or 3

This digital Flight Control System allows for greater precision and launch target accuracy.

The Soyuz 2.1b also sports an uprated Blok-I second stage engine, the RD-0124, which provides increased performance.

It was the second of three Soyuz 2 variants to fly, taking its first launch on December 27th, 2006.

The Soyuz 2.1b variant flies under two different national flags and has two different names for the same configuration.

When launching from Baikonur or Plesetsk, the rocket flies as part of the Russian Federal Space Agency, Roscosmos. For these missions, it is known as the Soyuz 2.1b.

When sold to Arianespace, the European Space Agency's launch management company, the rocket sports a few European modifications, like a European payload adapter and a European flight termination system.

When it flies for Europe, the rocket is known as the Soyuz ST-B.

Image: ESA

The Plesetsk Cosmodrome is located 800 km north of Moscow, Russian Federation.

The site was founded in 1957 to support Union of Soviet Socialist Republics ICBM launches of the R7 missile - from which the Soyuz rockets today are derived.

Plesetsk was not as busy as Baikonur in terms of satellite launches from its founding in 1957 to 2000 due to its location and ability to only launch crafts to Molniya and polar orbits.

With the fall of the Soviet Union and the Baikonur Cosmodrome becoming foreign territory for Russia, Plesetsk has been far more active since the 2000s.

It is primarily used for military and commercial launches to high inclination and polar orbits.

It has been the site of three fatal ground accidents that have killed 58 people.

In 1973, a Cosmos-3M rocket exploded on the launch pad killing 9; in 1980, a Vostok-2M rocket exploded during fueling, killing 48; in 2002, a Soyuz-U rocket exploded killing 1 person.