To the Moon, on Zond - Soviet computing in space

Continuing the discussion from CONvergence Apollo 11 Panel:

Here’s an illustrated article (in Russian) on the computers used in the Soviet space program at time of Apollo:

It was on the basis of “Argon-1” that the first space-based computer was created. The onboard computer Argon-11C was designed to control the movement of the L1 spacecraft from the Zond series during its flyby of the moon and aerodynamic descent to Earth when entering the atmosphere at the second cosmic velocity.

Here - in English - some details on the Argon 11c used in the Zond program. (Lots of Soviet computing history on this site.)

34kg, 14bit data, 128 words of core, 200k operations per second, and triply redundant.

The design of the triggered Argon-11C scheme was so successful that it was later repeated with the Argon-16 onboard computer, which can be safely called a cosmic long-liver. This computer has been used in a wide variety of spacecraft for over 25 years! About three hundred copies of the Argon-16 worked in the Soyuz, the Progress transport workers, the Salyut and Mir orbital stations. Believe me, for a space-based computer this is a big number.

Argon 16 in English here.

Via this article on the Soviet moon program, in Spanish. Via this thread on the HP museum forums.

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This is really interesting: Argon 11C used a a redundancy scheme with 3 parallel, but independent units and majority vote on the result, much like it’s used in aviation today.

From the “illustrated article” (Google translate):

In Argon-11C, for the first time in the practice of creating on-board computers, a node redundancy scheme was applied, which was called a triple structure with majoritarianization. Behind this tricky name hides an elegant design.

Structurally, the “Argon-11C” consisted of three identical functional blocks operating in parallel and independently from each other. At the inputs of each unit (there were 28 of them altogether) exactly the same information came from a variety of telemetry sensors. On its basis, each unit produced more than forty control actions.

And here began the most interesting. The final control actions were formed by the majority principle. That is, if at two of the three outputs they were the same, and at the third they were different, then the values worked out by the majority were taken as the basis.

magority-schema

Unrelated related: An article in Nature on how Apollo nearly became a joint US-Soviet mission:
https://www.nature.com/articles/d41586-019-02088-4
Apparently, Khrushchev planned to accept Kennedy’s offer (compare Soviets Planned to Accept JFK�s Joint Lunar Mission Offer), but plans eventually dissolved with the death of Kennedy.

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