Russia’s Soyuz-2.1v rocket has made a surprise launch Wednesday evening, lifting off from the Plesetsk Cosmodrome in the north of the country to deliver four military satellites into orbit. Soyuz lifted off at 20:14 Moscow Time (17:14 UTC), while the successful separation of all four satellites was announced four hours later.
Wednesday’s launch was not announced ahead of liftoff. While Russia has frequently conducted launches without prior announcement in the past, in recent years the dates of upcoming military launches have been published, or otherwise become public knowledge, in advance.
Despite the secrecy surrounding the launch, the Russian Government did quietly file the usual notices to airmen and mariners (NOTAMS and NOTMARS) advising of an upcoming rocket launch several days before liftoff. These alerts are used to warn pilots and sailors of the potential danger that the rocket could pose them – designating airspace closures and areas where debris from the rocket might be expected to land.
It is fairly common for Russia to issue such notices around the Plesetsk Cosmodrome, which is an important test center for the country’s ballistic missiles as well as its main military launch site.
Wednesday’s launch used as Soyuz-2-1v rocket with a Volga upper stage. This is a three-stage vehicle derived from the workhorse Soyuz family of rockets but optimized to carry smaller payloads. Soyuz-2-1v is based on the larger Soyuz-2-1b, but without the four boosters that make up the first stage of the classic Soyuz design.
The Soyuz-2-1b’s first stage is, therefore, the heavily modified version of Soyuz-2-1b’s second stage with its RD-108A engine replaced with a higher-thrust NK-33. The second stage is a Blok-I, the third of the Soyuz-2-1b, while the optional Volga third stage is used to ensure precise delivery of the rocket’s payload into its target orbit, or several different orbits if required.
The Soyuz 2-1b and 2-1v, along with the Soyuz-2-1a, make up the latest generation of a family of rockets that have served Russia, and formerly the Soviet Union, since the dawn of the space age. Soyuz traces its lineage back to Sergei Korolev’s R-7 missile, which in 1957 became the first intercontinental ballistic missile (ICBM) to fly. R-7 had a brief career as a missile, its liquid propellants and the resulting need to fuel the rocket immediately before launch quickly rendering it obsolete as new storable-propellant missiles were developed, however it found its niche delivering satellites to orbit.
A modified version of the R-7 had been used in October 1957 to launch Sputnik, the world’s first satellite, followed by Sputnik 2 with the dog Laika the following month. Later derivatives, with names including Vostok, Voskhod and Molniya launched the first humans into space, carried early probes to the Moon and deployed early scientific, reconnaissance and communications satellites.
Soyuz was an evolution of the Voskhod rocket, which had to be upgraded to accommodate the new Soyuz spacecraft which was designed to carry three cosmonauts to space stations in low Earth orbit. Its first flight came on 28 November 1966.
Initial Soyuz launches were dedicated to the Soviet human spaceflight program, with a few modified versions used to deploy a small number of reconnaissance satellites. The introduction of the Soyuz-U in 1973 changed this: the new rocket was intended as a replacement for the earlier Soyuz and also Voskhod, which at that time was still carrying out most military launches. Soyuz-U took over both crewed and uncrewed launches, and by its retirement in 2017 it had flown over 750 times, a record for any orbital carrier rocket.
The Soyuz-2 updated the Soyuz design for the twenty-first century, with digital flight control systems and upgraded engines among the enhancements. Soyuz-2-1a, the least-changed version, made its debut in 2004 with a suborbital test flight, before conducting its first orbital launch in October 2006.
Two months later the Soyuz-2-1b first flew, incorporating further modifications to the rocket’s third stage, with a new RD-0124 engine in place of the earlier RD-0110. Soyuz-2-1v was introduced in 2013 to carry smaller payloads, replacing earlier rockets in this role such as the Tsyklon, Dnepr and Kosmos-3M that were being phased out.
Wednesday’s launch was the fifth flight of the Soyuz-2-1v, and the fourth time it has flown with the Volga upper stage. The launch began at Site 43/4 of the Plesetsk Cosmodrome, which is shared by Soyuz-2-1v and its larger brethren. Site 43/4 is the same launch pad that has been used for all of the Soyuz-2-1v’s previous missions.
It is the only one of four Soyuz launch complexes at Plesetsk – all built in the 1960s – to remain operational, although nearby Site 43/3 is expected to come back online later this year. Following its use by a Soyuz-2-1b rocket at the end of May, the complex would have been converted to support the Soyuz-2-1v’s smaller first stage configuration. The pad will now be converted back for a Soyuz-2-1a launch, which could take place later this month.
Both the first and second stages of Soyuz-2-1v burn RG-1 propellant, a Russian rocket-grade kerosene, which is oxidized by liquid oxygen. The first stage’s NK-33 engine is one of a number originally built for the Soviet lunar program in the late 1960s and put into storage after that project’s cancellation. NK-33 was to have powered the second stage of N-1F, an operational version of the N-1 rocket which was tested between 1969 and 1972. N-1 was abandoned after the Soviets failed to get to the moon before the United States, having failed during first-stage flight on all four unmanned test missions.
Several projects were proposed to use the stockpile of leftover engines, with two – Soyuz-2-1v and the US Antares rocket – making it to the launch pad, although Antares has since switched to RD-181 engines. Russia intends to re-engine Soyuz-2-1v with the RD-193 when the stock of refurbished NK-33s has been expended.
Following ignition of the first stage engine and liftoff, Soyuz began a north-westerly climb away from the Plesetsk Cosmodrome. The first stage provided the initial thrust to lift Soyuz away from the ground and out of Earth’s atmosphere, burning for about 200 seconds. Shortly before first stage cutoff, the second stage ignited its RD-0124 engine, with stage separation occurring immediately afterward. This “fire in the hole” separation technique is used by Soyuz to keep propellant settled in the second stage tanks, simplifying its startup process. After igniting, the second stage burned for about four and a half minutes.
Once the second stage had consumed its propellant and shut down, Volga separated to begin its role in the mission. Developed from the propulsion module of the Soviet-era Yantar reconnaissance satellites, Volga was powered by an 17D64 engine, which burned unsymmetrical dimethylhydrazine and dinitrogen tetroxide. Designed to be restarted multiple times, Volga would have made several burns during Wednesday’s mission before deploying the four payloads into their pre-planned orbits.
It is too early to identify the four satellites that Soyuz has placed into orbit with Wednesday’s launch. The clandestine nature of the launch suggests that they could be part of Russia’s satellite inspection and space surveillance program, speculated to be named Nivelir. A previous Soyuz-2-1v launch in June 2017 supported this project with the deployment of three small satellites which then maneuvered in orbit to simulate an inspection spacecraft gathering data on a foreign power’s spaceborne assets. There are, however, many other intelligence, technology demonstration or other applications that these satellites may be intended to fulfill.
In lieu of calling the spacecraft by a project name or production designation, Russia will have given the satellites generic designations under the Kosmos series. Most likely, the satellites will be named Kosmos 2535, 2536, 2537 and 2538, as these designations are assigned sequentially and the Uragan-M navigation satellite launched at the end of May was numbered Kosmos 2534. The Kosmos series has been used since 1962, with the Soviet Union initially using it to obfuscate the identities of prototype spacecraft and failed interplanetary probes, as well as military satellites.
Russia’s next launch is expected on Friday, when a Proton-M rocket will deploy the Spektr-RG space observatory in a mission that was rescheduled from late June.
The next Soyuz launch is slated for 20 July, with a Soyuz-FG rocket carrying three cosmonauts to orbit aboard the Soyuz MS-13 spacecraft on the first leg of their journey to the International Space Station.
A further Soyuz launch at the end of the month will carry an automated Progress resupply spacecraft to the outpost, while two further military launches were also announced to fly no earlier than July aboard Soyuz-2-1a rockets – either of these would need to use the same launch pad that supported Wednesday’s launch.