The triumph and death of the lunar Rover

The triumph and death of the lunar Rover

Russian space systems holding (RCS, part of the Roscosmos state Corporation) continues to publish unique historical documents from 1972 that reveal previously unknown details of the history of space exploration.

This “Russian Spring” reported in a press-service of the holding company “Russian space systems”.

Today, the company’s website published an electronic version of the 1972 document “radio Engineering complex of the automatic station” Luna-17 ” and ” Lunokhod-1 “(object E8 # 203)”, which discusses various aspects of the operation of the automatic station “Luna-17” and “Lunokhod-1”.

The document allows you to evaluate how the work was done on the errors that made it possible to conduct the next lunar mission almost perfectly.

Prepared more than 60 years ago by Soviet engineers, the document contains detailed information about the operation of onboard transmitters, antenna systems, telemetry systems, photographic equipment and small-frame television system of the lunar Rover, which became the “eyes” of its “drivers” on Earth.

In addition to its historical significance, the document is of interest from the point of view of understanding approaches to processing information obtained when using devices in real conditions.

The report on the work of the radio engineering complex “Luny-17” and “Lunokhod-1” is divided into four parts, each of which provides an analysis of the preparation, ground testing and operation in real conditions of individual systems.

The first part of the document deals with the long-distance radio communication and the operation of the corresponding on-Board equipment, and then describes the operation of the system malokakhovka
television and totelevision system, and it concludes with analysis of the functioning of ground equipment from antenna system to the workplace “drivers” of the Rover.

In particular, the document describes the first radio session with the just-landed “Luna-17”:

“Immediately after planting, produced a radio session with the transfer totelevision panoramic images, which allowed to evaluate the terrain in the landing area, the condition of the ladders for the gathering of “Lunokhod-1″ migratory stages and to make the choice of direction of movement on the moon.”

But the description of the problems on Board the “Lunokhod-1” and circumstances of their occurrence:

“During the fourth lunar day, when conducting communication sessions through the second set of transmitter (C-163 M-2), there was a decrease in informative power. The second transmitter functioned normally until 7 lunar day. In session # 707 (may 11, 1970), the informative power gradually decreased, at some points reaching zero. By the time of the failure, the transmitter had run 212 hours and 36 minutes.”

The authors of the document analyze in detail the reasons for the early failure of both lunar Rover transmitters (the warranty period was 250 hours, and they worked 138 and 212, respectively).

To do this, bench tests of similar devices were conducted on Earth.

As a result, it was established: “the most likely cause of abnormal operation of the device is the failure of the 1a401 diode in the FM-1K modulator.” The reason for the problems was in the design and manufacturing technology of diodes. The changes were made as quickly as possible. Already at the end of 1970, ” manufacturers took measures to improve the reliability of diodes.”

The document also contains evidence of the death of ” Lunokhod-1»:

“After the 7th lunar day, only telemetry was transmitted from the aircraft at low informative power, while television and telemetry were transmitted at normal power. On the twelfth day of the moon, the transmitter did not turn on, and the object’s onboard power failed. Lunokhod-1 has ceased to exist.”

Another drawback of the lunar Rover’s communication line, identified during operation, is also subject to careful analysis:

“When operating on-Board transmitters via a sharp-pointed antenna, it is possible to obtain a signal-to-noise ratio of 500-600 in the 50 kHz band with a specified gain of 30. In fact, in communication sessions, this ratio did not exceed 200.”

The text of the document contains interesting information about the work of small-frame television.

Despite the fact that this system proved to be excellent and worked without failures, in practice, a number of design flaws were identified that needed to be fixed for the next lunar Rover mission.

We are talking about the height of the cameras and the need to use a lens hood. In addition, the developers of devices for “Lunokhod-1” had to face another problem:

“It should be noted that the reflection coefficient of the lunar surface in the landing zone of Luna-17 was significantly lower than that determined by astronomical methods from Earth, which reduced the light modulation of the video signal and image contrast.”

In total, the small-frame television system worked on the moon for 120 hours during 11 lunar days. Taking into account the work during the tests, it has worked more than 200 hours with a resource according to the technical task — 150 hours during three lunar days. More than 20,000 frames were transmitted to Earth from the moon.

The phototelevision system, which transmitted famous panoramas of the moon to Earth, also performed well overall.

There were only minor problems with the synchronization of one of the cameras, as well as the low gain of the antenna and the long transmission period (each circular panorama was transmitted for at least 25 minutes).

Despite this, 218 panoramas were received from Lunokhod-1.

Interestingly, the phototelevision system was used to move the lunar Rover when the radio line could no longer transmit small-frame television data:

“Phototelevision panoramas were used to evaluate difficult sections of the lunar Rover route. This analysis was performed during the first, second, third, and sixth lunar days. On the 11th lunar day, the lunar Rover was moving in start-stop mode using panoramas obtained by the FT system. the Maximum distance to which the self-propelled vehicle could be safely moved was 15 meters.”

The ground control complex also received several comments.

Such a detailed “medical history” of the first lunar Rover and carefully done work on errors made it possible to conduct the second lunar mission at a very high level and significantly advance in the development of remote control systems for self-propelled automatic stations for the study of other planets.

RCS Deputy General Director for strategic development and innovation Yevgeny Nesterov:

“We at the company have great respect and interest in the history of the industry and the priceless historical heritage that is stored in our archives. I am glad that it is gradually becoming available to all those interested in the history of space exploration. The document that we publish today is a classic example of how scrupulously we work on errors after any flight tests of equipment. This is the basic principle of development-constantly searching, finding, recognizing and correcting mistakes. This historical experience helps young developers understand, first, how hard it is to win in space by trial and error, and, secondly, to realize that they are part of a great history, in which the right to make a mistake is necessarily the duty to correct it. This was 50 years ago, this is happening now, and it will always be so.”

For several generations, RCS specialists have been constantly honing instrument technologies based on a constant analysis of the experience of real space flights.

For almost half a century since the events described in the published document, “work on errors” is done at the end of each mission and allows you to improve space instruments using the best available technologies.

Today, the RCS continues to develop telemetry, communication and control systems that can be used in future Russian and international missions to study the moon.

The specialists of the holding in recent years has conducted large-scale modernization of the Russian ground control complex of spacecrafts: was created from the ground of the Eastern command and measuring point, an upgraded ground control, including the deep space network, which has been successfully operating in the framework of the project “Eczemas”.

Soon the RCC will participate in the creation of a system of deep space communications on the cosmodrome “East”.

At the same time, the holding’s engineers are constantly improving the capabilities and manufacturing technologies of onboard telemetry systems and are ready to develop and produce such devices for promising Russian lunar vehicles.

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