Strela (russian: Стрела, for ''Arrow'') is a Russian (previously

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

) military

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...

constellation operating in

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

. These satellites operate as mailboxes (" store-and-forward"): they remember the received messages and then resend them after the scheduled time, or by a command from the Earth. Some sources state the satellites are capable of only three months of active operation, but through coordination with others they can serve for about five years. The satellites are used for transmission of

encrypted In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can deci ...

messages and images.

History

The first three satellites,

Kosmos 38 The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in ...

(reentered 8 November 1964), Kosmos 39 (reentered 17 November 1964) and

Kosmos 40 The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in ...

(reentered 17 November 1964), were launched on 18 August 1964. Five different types of Strela satellites have been launched, designated Strela-1 (1964-1965), Strela-1M (1970-1992), Strela-2 (1965-1968), Strela-2M (1970-1994), and Strela-3 (1985-2010). Strela satellites are also used for the civilian

Gonets Gonets (Russian Гонец, for ''Messenger'') is a Russian civilian low Earth orbit communications satellite system. It consists of a number of satellites, derived from Strela military communications satellites. The first two satellites, whic ...

program. The current version of Strela, Strela-3M is also known as Rodnik. In 2018 Austrian counterintelligence authorities identified an officer of the

Bundesheer The Austrian Armed Forces (german: Bundesheer, lit=Federal Army) are the combined military forces of the Republic of Austria. The military consists of 22,050 active-duty personnel and 125,600 reservists. The military budget is 0.74% of natio ...

, Martin M. as a Russian spy. During the investigation, Austrian counterintelligence found a small suitcase. It had radio-communication equipment built into it so that Martin M. was able to connect to Strela-3 satellites and receive and send encrypted messages. The authorities also found a list of times when the satellite was positioned over Austria.

Technology

The following observations were published in 2011: On 244.512 MHz a Strela-satellite generates a 0.5s long 'trigger pulse' every 60 seconds; the purpose is to activate ground based transmitters waiting to send a message. Satellites were identified by measuring the time of closest approach using a Doppler curve. Received messages are then re-transmitted on the second known frequency at 261.035 MHz.

Accidents and incidents

* At 16:56 UTC on 10 February 2009,

Kosmos 2251 Kosmos-2251 (russian: Космос-2251 meaning ''Cosmos 2251''), was a Russian Strela-2M military communications satellite. It was launched into Low Earth orbit from Site 132/1 at the Plesetsk Cosmodrome at 04:17 UTC on 16 June 1993, by a Kos ...

, a retired Strela-2M, collided with the operational

Iridium 33 Iridium 33 was a communications satellite launched by Russia for Iridium Communications. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 UTC on 14 September 1997, by a Proton-K rocket with a Block DM2 up ...

satellite.

References

{{Reflist, 2

External links

Encyclopedia Astronautica - Strela
Military satellites Communications satellites Communications satellites of the Soviet Union Military equipment introduced in the 1960s