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Strela and Gonets


Tyneside, UK
2019 Dec 12
Thursday, Day 346

Maintained by:









Strela and Gonets:



The Systems

Strela and Gonets are both what are termed "store/dump" or "store and forward" messaging systems. Messages can be transmitted from anywhere on Earth, stored aboard the satellite and then sent down to a ground station when in range. Their lineage goes back nearly forty years.

These satellites form two main constellations and there are some, more-recent developments that have seen the emergence of variants and, in one case', an upgraded satellite type. Global coverage is achieved by having many active satellites in orbit simultaneously so a user does not have to wait long before one comes by.

Strela-3

Strela is the military/government version of the system. As to its users, any list of Russian governmental, security or military organisations probably covers them. They range potentially from agents in the field to Russian embassies, or from ships at sea to government trade delegations in foreign countries. By use of coding, messages are secure.

Strela-3 is the latest incarnation of a line of military satellites going back to 1964 and the earliest days of the Soviet space programme. It was developed to support tactical resources on the ground away from the borders of the Soviet Union. It took about eight years of tests before the first operational satellite was orbited.

This mode of operation, although only suitable for short messages, requires significantly less equipment than would be needed a point-to-point system, and allows a user to be mobile. Because the transmission is directed upwards, it is difficult to intercept. A transmission from the satellite can be detected easily but the recipient on the ground is virtually impossible to determine because they might be anywhere within a circle of 1500 kilometres radius. This makes it very useful for supporting clandestine activity.

Gonets

Gonets-MGonets-D1 satellites support a semi-public version of the Strela type of network. Russia is marketing a commercial version using more sophisticated Gonets-M. So far (2010 September), two Gonets-M satellites have have been put into orbit

This diagram showing Gonets communications coverage is equally applicable to Strela. It depends on having a number (ideally 20 or so) of operational satellites in space at any one time. Satellites are spread around the orbit.

Originally with Strela, there was a single orbit plane but, with time, the system evolved into several orbit planes distributed round the Earth to ensure that a user does not have to wait too long before before a satellite comes into view.

Gonets, similarly, started with a single orbit plane but now there are two. Message relay is not instantaneous but can be achieved in minutes rather than hours.

The image is on the right is taken from a video animation made available through the Gonets-Satcom web site. It shows an idealised view of a large constellation of Gonets.

Design

The current Gonets and Strela-3 satellites are very similar to look at. What is different is some of the electronics and the communications packages. Shown here is Gonets-M, the latest version. It differs from Gonets-D1 by having an additional, third helical aerial. It also has two extra fold-out panels carrying solar cells to increase the capacity of the power supply. They can be seen extending downwards at an angle.

Gonets M satelliteThe drum shape is created by the solar arrays. They hide a pressurised cylindrical body with domed ends, a standard Soviet/Russian design feature. Within the pressurised section are the operational electrics and electronics. It also has a thermal regulation system for maintaining the internal temperature.

The boom with a mass at the end provides the gravity-gradient stabilisation and is retracted for the launch stage of the mission. This passive form of stabilisation is supplemented by magnetic damping of rotation and nutation but does not offer great accuracy. It is quite sufficient for satellites like Strela or Gonets and it does not rely on electronics or electrics.

Only when the satellite has achieved an Earth-pointing orientation using gas jets is it extended for use with the balancing mass at the end furthest from Earth. The gas jets can also be used for small adjustments of the orbit.

Aerials for both transmission and reception are conical helices that fold out away from the satellite body on achieving orbit. The whole arrangement is very similar to the Tsikada/Nadezhda navigation satellites, but on a smaller scale.

Launch

Gonets for LaunchOriginally, Gonets and Strela were put into orbit in multiple launches of six satellites using the intermediate-sized Cosmos-3M launch vehicle.

With that rocket being phased out of service, the job has been taken over by Rockot - capable of carring three satellites at a time. Recent launches have seen mixed batches of Strela and Gonets going into space at the same time.

The picture shows a cluster of three satellites stowed for launch. This may be a triplet for launch by Rockot or there is a minor possibility it is one of a pair that were carries on a six-payload Cosmos-3M launch.

The image originates from Reshetnev company - builder of both Strela and Gonets.
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