The radio systems of the early Luna probes

Sven Grahn

The early lunar probes launched by the Soviet Union (Luna 1-3) carried rather simple radio systems. This article is a description of these systems and how they worked, as well as can be determined so long after the actual events. In general the probes carried

The S-band radar tracking provided an initial estimate of the state vector and the subsequent trajectory, which was then updated by ranging measurements made through the VHF ranging link (RTS-12B).

Post-Cold War account of Luna 1-3 radio systems

This account is based on information from (12), "Unforgettable Baikonur". The table below summarizes the information in that document.

Vehicle Radio system Phase

Pre- December
 1958 launch

Luna-1 Luna-2 Luna-3
Probe Jupiter-1 Cruise


19.993 MHz 19.993 MHz


  Jupiter-2 Cruise



39.986 MHz 39.986 MHz
  RTS-12B down Cruise

183.6 MHz

183.6 MHz 183.6 MHz 183.6 MHz
  RTS-12B up Cruise

102 MHz

102 MHz 102 MHz 102 MHz
3rd stage



19.995 MHz

19.995 MHz 19.997 MHz





19.997 MHz

19.997 MHz 20.003 MHz


  RTS-8E Launch

183.6 MHz

183.6 MHz



  RTS-12A Launch



182.0 MHz 182.0 MHz
  Fakel-S Launch

2.7-2.8 GHz

2.7-2.8 GHz 2.7-2.8 GHz 2.7-2.8 GHz

The RTS-12B system on 183.6 MHz for flights up to and including Luna-2

The RTS-12B system for probes up to Luna-1 had a complex pulse-position modulation system, where the frequency shift pulses of the “velocity vector” system with the period 0.5 second were somehow transmitted together with the short (10 milliseconds) pulses of the pulse-position modulation (PPM) telemetry (15 ). A complete telemetry frame contained 120 measuring channels and was transmitted in 2 minutes, i.e. one interrogation, or "data word", per second. The frame marker consisted of three pulses. It is unclear how the telemetry pulses were modulated on the carrier.

The "velocity vector" frequency shift pulses are given as 0.5 seconds long. It is unclear if this is the rise time or the total back-and-forth pulse time. Interestingly, the "velocity vector" system worked well on Luna-1, but the telemetry modulation in the RTS-12B system did not work on that flight.

For Luna-2 the flight the RTS-12B system was changed so that the ranging system and telemetry system did not work at the same time, but rather in turn. Also the telemetry part of the system used the same modulation as the “Jupiter” system - i.e. PDM (Pulse-Duration Modulation). A narrow-band filter had to be added to the RTS-12B ground receiver to make up for the fact that a keyed carrier was used for telemetry. The ranging system worked by bursts of pulses with short-term change in the carrier frequency.

The "Jupiter" systems on 20 and 40 MHz

The RTS-12B was evidently causing problems in the early phase of the program, so on the third launch in December 1958 (which failed) the "Jupiter-1" system was added.  That uses two long ribbon antennas on the space probe.   It replicated the same telemetry information as was carried by the RTS-12B system on a frequency of 20 MHz.  Just as with the RTS-12B system 120 parameters were transmitted in a 2 minute cycle. So, the "Jupiter-1" system added in late 1958 saved the scientific mission of Luna-1 in which the RTS-12B system on VHF failed.

For Luna-2 a second low-frequency telemetry system, "Jupiter-2", operating near 40 MHz, was added. The transmitter “Jupiter-2” worked in the pauses of transmitter “Jupiter-1” (by opposite coding, transferring the same information).
The receiving system for “Jupiter” at Baikonur consisted of two troop receivers of R-250 type (see image on right. Thanks to Don P Mitchell for the picture).Recording of information was conducted by tape recorders and photoregistering equipment common with the RTS-12B station.

An antenna field of five rhombic shortwave antennas were erected on wooden posts and were used for both "Jupiter-1" and "Jupiter-2".
These wire antennas extended a sector of 150° in azimuth with the center axis to the south. The antennas were switched by hand as the spacecraft moved from the east to the west. In (14) the layout of a rhombic array at the Simferopol tracking station is shown (see image below right). A fan-shaped array of nine rhombic antennas are indicated as being used for space tracking. A pair of rhombic antennas of different size is indicated as being a "day/night pair" for terrestrial communications, most probably with Moscow. The rhombic antennas at Baikonur were modified in 1960 to be bidirectional. This provided around-the horizon coverage. the same is probably true for the Simferopol array. In 1959 the Baikonur rhombic array only had coverage to the south where the Luna probes traversed the sky. The modification of the Baikonur array in 1960 was done to support the shortwave "Signal" beacon on the space vehicles in the Vostok program, the first test vehicle of which was launched on 15 May 1960. 

Luna-3 only supported by Simeiz and far east station in Yelizovo

For Luna-3, the spacecraft that took pictures of the far side of the moon, a new radio system had been developed by NII-885 under the management of Yevgeni Boguslavsky (13 ). The system transmitted the images of the moon, relayed telemetry, measured the range and range rate, and received commands from the ground and acknowledged the reception of these commands. The "Jupiter-1" system was deleted and only the "Jupiter-2" system was retained. 

During the flights of Luna-1 and Luna-2 data reception was performed at Baikonur and the temporary tracking station at Simeiz in the Crimea. During the flight of Luna-3 no reception of signals out to lunar distances was made at Baikonur - only out to 40000 km. Only the stations at Simeiz and Yelizovo on the Kamchatka peninsula communicated with Luna-3 far away from the earth.

RTS-8E system on 183.6 MHz on the carrier rocket used up to and including Luna-1

The RTS-8E system had a pulse-position-modulated radio transmitter with a 100 W pulse power. It carried 26 measuring channels on 100 interrogations per second (one data word every 10 milliseconds). Each measurement "word" consisted of a reference pulse (7 microseconds long) and a measuring pulse (4 microseconds long). There were 3 additional channels for the calibration. Frame synchronisation was provided by a pause approximately 1000 microseconds (1 millisecond)? The RTS-8E system was a modification of RTS-8, which was developed in 1956 to test the R-7 missile, but lost the design competition to the Tral system.

RTS-12A system on 182.0 MHz on the carrier rocket used on Luna-2 and Luna-3

This system was a very slight modification of the RTS-8E brought about my lowering the transmission frequency to avoid any risk of interference with the RTS-12B probe transmitter on 183.6 MHz. The RTS-12A adopted the frequency 182.0 MHz

Sergei Korolev writes about the subject

In a document written in early 1958 (9) Sergei Korolev described plans for the early Luna probes:

 ...."The radio system operates in the wavelength range 1.6 - 2.5 m. The range from the earth to the spacecraft is measured by an active radar. The pulse signal of the range determination is re-sent as a range signal and used on the earth to measure the range from the earth to the spacecraft. From the distance 20.000 - 30.000 km to the Moon, the range from the spacecraft to the Moon starts to be measured simultaneously with the measurements the earth - spacecraft distance. Beside the pulse signals, the on-board radio transmitter sends to the earth a continuous signal with a power of the order of 10 W to determine the spacecraft velocity. This results in the signal power on the earth of the order of 0.1 microwatts only. Receiving such a signal will be made by radio astronomy dishes in Simeiz". .....

Simeiz is a small city near Yevpatoria in the Crimea. In all probability Korolev describes the ranging system operating on approx 102 MHz uplink (probably equivalent to the uplink 101.965 MHz used for Luna-16, 20...) and 183.6 MHz downlink (see Luna 1 or Luna 2 below). The translation of Korolev's text was provided by Dr Stas Barabash, Swedish Institute of Space Physics, Kiruna.

In the Energiya history book (11) the control center for the lunar missions is described as temporary and set up on the Koshka mountain near the city of Simeiz and using the facilities of the Crimean Observatory and the Physical Institute of the USSR Academy of Sciences. In (11) it is also indicated that the radio systems of the early Luna probes were developed by NII-885 under the leadership of Mikhail S. Ryazanskiy, Chief Designer of Radio Control Systems.

Details of Luna 1-3 radio systems in TASS announcements and foreign tracking reports

Luna 1

Luna 2

Luna 3

Frequencies announced in the West

Several sources have given other frequencies for Luna-1. In Nature (19) 71.2 and 212 MHz were mentioned as frequencies for Luna-1 but without any details.

It is entirely believable that there were signals on these frequencies and that at least Hawaii got them. On the last stage of the A-2 (Vostok-type in Soviet parlance) vehicle there are hairpin shaped antennas very well matching the two frequencies. It is doubtful if these signals could be heard very far out from Earth since they were probably rather broadband containing high speed telemetry from many sensors associated with the propulsion system in the last stage. Also, the batteries for these transmitters probably went dead quickly. 

But why are not these frequencies mentioned in (12) which reveals so much previously secret information? And where does this frequency information in Nature come from ? An unintentional leak from Jodrell Bank?


  1. "Simplified Tracking Gear Provides Much Data", Missiles and Rockets, March 16, 1959, pp. 29-33.
  2. Mastery of Cosmic Space by the USSR, official TASS communiques and materials from the central press 1957-1967, Nauka Publishers, Moscow 1971.
  3. V.A. Kotelnikov, .M. Dubrovin, O.N. Rzhiga and A.M. Shakhovsky. "Reception and investigation of the properties of radio signals from Soviet Space Rockets".
  4. Hearings before the Committee on Science and Astronautics and Special Subcommittee on Lunik Probe, U.S. House of Representatitives, Eighty-Sixth Congress, First Session, U.S. Governement Printing Office, Washington D.C., 1959. The hearings were held during the period May 11-29, 1959.
  5. J.G Davies, A.C.B. Lovell, Observations of the Russian Moon Rockets Lunik II and III, Space Research 1, Proceedings of the first COSPAR conference, 1960.
  6. A telegram from Jodrell Bank to SPACE CONN NASA WASH DC dated 4 October 1959
  7. A telegram from Jodrell Bank to SPACE CONN NASA WASH DC dated 7 October 1959
  8. A telegram sent by Prof. J.B Davies at Jodrell Bank to MEGER, PRAHA on 15 October 1959 describing signal from Luna 3.
  9. S.P Korolev (edited by M Keldysh), "The Creative Legacy of Academician S.P. Korolev", Nauka, Moscow 1980, p.402.
  10. V.Ye Demidov, "Radio Bridge- 'Earth-Moon-Earth'." Znaniye Press, Moscow 1967.
  11. Yu. P Semenov, ed. Raketno-Kosmicheskaya Korporatsiya "Energiya" imeni S.P. Koroleva 1946-1996, 1996, p. 97
  12. K.V.Gerchik (ed.), "Nezabyvaemy Baikonur" (Unforgettable Baikonur), 1998.
  13. Deputy chief designer of the Scientific Research Institute. of Radio Instrument Building.
  14. The Simferopol Space Flight Center, National Photographic Interpretation center, June 1969, Report RCA-03/0017/69 
  15. Called pulse-time modulation in (12))
  16. Martin Caidin, "Race for the Moon" William Kimber Publisher, London 1960.
  17. NATURE, January 10, 1959, page 83.

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