Serpukhov-15

• 1. Introduction

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  Serpukhov-15 is a military townlet sitting near Kurilovo in Kaluga Oblast, about 35 kilometres from the city of Serpukhov. From the outside it resembles little more than a cluster of buildings and seven domed structures rising from the Russian countryside. Inside, operators watch a stream of satellite data for a signal that no one wants to see: the heat plume of ballistic missiles rising from the continental United States.

  The site is the western control centre for Russia's Oko early warning satellites. Its work feeds into the Main Centre for Missile Attack Warning, with processed data flowing to the Russian Aerospace Defence Forces centre at Solnechnogorsk. That chain of information could, in theory, trigger a launch on warning of the A-135 anti-ballistic missile system.

  The name itself is a code name, following the established practice for closed cities and military facilities in Russia. How this obscure site became a nerve centre for nuclear early warning, and what happened on a September night in 1983 when it nearly changed history, is a story worth following.

• 2. The Oko Constellation

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  Oko relies on two distinct types of satellites to keep watch over the United States. The older US-K satellites trace highly elliptical molniya orbits, which carry them high over the northern hemisphere at particular times of day, giving them periodic coverage of American missile fields. To maintain continuous coverage of those fields, four US-K satellites need to be operational at any given moment. The system can accommodate up to nine in orbit simultaneously.

  The US-KMO satellites take a different approach entirely. Positioned in geosynchronous orbit, they provide unbroken, continuous coverage rather than the periodic windows the molniya orbit allows. Across both generations, 101 satellites have been launched into the Oko programme.

  The system was placed on combat duty in 1982. Two milestones mark the close of its operational life: the last US-K satellite, Kosmos 2469, launched on the 30th of September 2010, and the final US-KMO satellite, Kosmos 2479, lifted off on the 30th of March 2012. Both generations are due to be replaced by a system called EKS.

• 3. The Facility's History

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  Long before Oko existed, the ground at Serpukhov-15 served a different military purpose. In 1960 the site housed missiles belonging to the S-25 Berkut air defence system, part of a ring of Soviet anti-aircraft defences. A subsequent plan called for it to serve as one of the intended bases for A350 missiles in the A-35 anti-ballistic missile system, though that stage was never completed.

  The Oko control centre was constructed later and reached combat readiness in 1982. Photographs of the site reveal a compound of buildings alongside seven domed structures, which are presumed to contain the antennas that keep the facility in contact with its satellites.

  As the western control centre, Serpukhov-15 communicates with geosynchronous satellites occupying four of seven reserved orbital positions. Those four slots, designated Prognoz-1 through Prognoz-4, look out over the Atlantic. The three remaining positions, oriented over the Pacific, fall under the jurisdiction of the eastern centre at Pivan-1 in the Russian Far East.

• 4. The 1983 False Alarm

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  On the 26th of September 1983, the Oko system triggered a major alert. The satellite network reported the launch of five Minuteman intercontinental ballistic missiles from the United States. The system had only recently become operational, which meant its reliability had not been proven under real conditions.

  The officer on duty that night was Lieutenant Colonel Stanislav Petrov. He weighed the alert against a critical absence: early warning radar had not corroborated the satellite report. Radar confirmation is a standard cross-check, and its absence gave Petrov reason to doubt what the screens were showing him. He discounted the reports.

  Investigators later concluded that the system had misidentified a particular combination of circumstances involving high clouds and the conditions of the autumn equinox. Five missiles, had they been real, would have represented a surprisingly small first strike for a nuclear power to launch, which added a further reason for scepticism. Petrov's decision to treat the alert as a malfunction rather than a genuine attack meant the false alarm never escalated beyond the control room.

• 5. The 2001 Fire

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  A fire broke out at the Serpukhov-15 control centre on the 10th of May 2001 at 2:20 local time. Military personnel initially attempted to fight the blaze without outside assistance. An hour later, at 3:20 local time, they called the civilian fire brigade.

  Firefighters found the blaze concentrated in the gap between the second and third floors of the affected building. One hundred firefighters were eventually involved in the response, and media reports described the building as burnt out.

  At the moment the fire started, the Oko constellation consisted of four satellites, all US-K models in molniya orbits. Those satellites require contact from a ground station every two or three orbits to maintain their orbital positions. When the fire cut communications, ground control was lost for 12 hours. The consequences proved lasting: Kosmos 2340 and Kosmos 2351 were lost immediately, while Kosmos 2368 and Kosmos 2342 degraded over the following year due to the negative effect on their orbits. The centre was reported to have restarted operations on the 20th of August 2001, roughly three months after the blaze.