Russian Rokot launch vehicle lofts three military satellites

by Chris Bergin

A Russian Rokot launch vehicle – with a Briz-KM Upper Stage – has launched from the Plesetsk space center in northern Russia, carrying three Rodnik-class satellites. The launch took place at 02:27 UTC on Thursday in a launch that is the beginning of the end of the Rokot rocket.

This Russian launch system is tailored to payloads requiring a performance of at least 1,950 kg for launches into Low Earth Orbit (LEO). The three-stage liquid fuelled rocket has dedicated launch facilities at Plesetsk Cosmodrome under the control of Eurockot.

It is set to retire in just a few launches time.

Rokot – also referred to as “Rockot” – is a fully operational, three stage, liquid propellant Russian launch vehicle which is being offered commercially by Eurockot Launch Services for launches into low earth orbit. The German-Russian joint venture company was formed specifically to offer this vehicle commercially.

The Rokot launch vehicle uses the SS-19/(RS-18) Stiletto ICBM for its first two stages.

The SS-19, which was originally developed as the Russian UR-100N ICBM series, was designed between 1964 and 1975. Over 360 SS-19 ICBMs were manufactured during the 70s and 80s.

The Breeze-KM third stage uses a re-startable storable liquid propellant engine that has been used in many other Soviet space projects.

The booster unit – which provides the first and second stages of Rokot – is taken from existing SS-19 missiles and is accommodated within an existing transportation/launch container. The third stage – which provides the orbital capability of the launcher – is newly manufactured.

This upper stage contains a modern, autonomous control/guidance system which controls all three stages. The upper stage multiple engine ignition capability allows implementation of various payload injection profiles.

The Rokot second stage has an external diameter of 2.5 meters and a length of 3.9 metres. It contains a closed-cycle, turbopump-fed, fixed main engine designated RD-0235 and verniers designated RD-0236 for directional control – as listed in the 200 page vehicle overview presentation (L2).

Separation of the first and second stages is a “hot separation” – due to the fact that the vernier engines are ignited just before the separation. The exhaust gases are diverted by special hatches within the first stage.

A typical Rokot launch profile – via EuroRockot

After separation, the first stage is braked by retro rockets, then the second stage main engine is ignited. Like the first stage, it contains a common bulkhead and a hot gas pressurization system.

The Breeze-KM (Or Briz-KM) stage – which has now been adopted as the standard version of the third stage for the commercial version of Rockot – is a close derivative of the original Breeze-K stage flown during the first three Rokot flights.

Briz-KM upper stage – via L2.

It comprises three main compartments which include the propulsion compartment, the hermetically sealed equipment compartment and the interstage compartment.

To allow larger satellites to be accommodated and to reduce dynamic loads, structural changes to the Breeze-K stage were introduced.

The structure of the equipment bay of the original Breeze-K stage has been widened and flattened by redistribution of the control equipment.

The Rokot’s latest mission was military by nature, as such little is known about the payloads. However, the Rodnik satellites are believed to be a version of the Gonets-M spacecraft, which are also called Strela-3M satellites. Their designation on the manifest classes them as Kosmos 25XX x3 (Rodnik blok #16).

The Gonets-M satellites – according to the Russian Space Agency – are intended to provide digital user terminal GLONASS positioning data, as well as electronic mail services. However, this is understood to be inaccurate, with Gonets-M having no role in the GLONASS operation.

The Gonets-M satellites are upgraded versions of the Gonets satellites, a derivative of the military Strela-3 satellite system. Rodnik satellites are believed to be the military version of the spacecraft family.

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