Russia and Navigation Systems

SOVIET APPLICATION OF SPACE TO

THE ECONOMY

By Lani Hummel Raleigh*

1971-1975

IV. NAVIGATION SATELLITES

An earlier section of this report explained that the Soviet Union acknowledges its use of navigation satellites, but does not explicitly identify any particular flight as used for that purpose. Hence, it is assumed that in the early stages such flights serve military purposes in the same way that the United States developed Transit first for use with its Pol arts submarines, and then by stages extended the use to other naval vessels, and now makes navigation satellite data available to merchant ships of any nation willing to acquire the necessary receiving equipment and computers which permit use of the data on satellites, from which ship position may be derived.

It is possible, even probable, that a similar transition is occurring within the Soviet navigation satellite program, and thus in time, the flights will be identified, as they must be if merchant ships or aircraft are to use them on an open, unclassified basis, or if international use is to be made.

A. SOVIET REFERENCES TO NAVIGATION SATELLITES

Leonid Sedov stated as early as 1965 that space was already being used for communications, weather reporting, and preparation of precise maps of the world. (52) In January 1966, the new Five Year Plan made specific reference to using space for communications, weather reporting, and navigation. (53)

Mstislav Keldysh was quoted shortly thereafter as saying that "The utilization of satellites and rockets for radio and television communications, navigation, and meteorology has been put into operation." (54) He repeated similar words at a meeting of the Soviet Academy of Sciences held June 27, 1966. He made similar statements in April 1967, and in November 1967. (55)

One of the most explicit references to Soviet navigation satellites appeared in 1966 in a magazine article which stated that the precision of such devices is constantly improving as reference points for shipboard and aircraft navigation systems. Coordinates can be determined to an accuracy of 200 meters. (56)

A short book devoted to the subject was issued in 1969. (57)

A 1968 broadcast mentioned a proposal for an air and ship navigation and traffic control system which would use 24 satellites to give complete coverage. There is no positive clue that such a system is in the process of being implemented at the present time. (58)

Finally, as mentioned earlier in this study, in connection with the launch of 8 satellites by one launch vehicle on April 25, 1970 an article in Red Star hinted vaguely at the uses of such multiple launchings for science, communications, and navigation; watching ionospheric processes; and radio astronomy by the interferometer technique. This is not sufficiently specific to be conclusive, for any one of these uses, although today 'the preponderant Western view is that they serve a communications purpose.

Recent mention of navigation satellites or a navigation satellite system are noticeably absent from the Soviet press.

B. ACTUAL NAVIGATION SATELLITE FLIGHTS

(See the section elsewhere in the web site on the use of the C-l vehicle, and the sections on navigation satellites.)

References:

(A) SOVIET SPACE PROGRAMS, 1971-75, OVERVIEW, FACILITIES AND HARDWARE MANNED AND UNMANNED FLIGHT PROGRAMS, BIOASTRONAUTICS CIVIL AND MILITARY APPLICATIONS PROJECTIONS OF FUTURE PLANS, STAFF REPORT , THE COMMITTEE ON AERONAUTICAL AND SPACE .SCIENCES, UNITED STATES SENATE, BY THE SCIENCE POLICY RESEARCH DIVISION CONGRESSIONAL RESEARCH SERVICE, THE LIBRARY OF CONGRESS, VOLUME – I, AUGUST 30, 1976, GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976,

52. TASS, Moscow, December 31, 1965, 1612 GMT.

53. TASS, Moscow, January 5, 1966, 1130 GMT.

54. Pravda, Moscow, April 3, 1966.

55. Moscow Radio, April 12, 1967, 1355 GMT; Moscow Radio, November 5, 1967, 0905GMT.

56. Nadezhdin. D., Space Science in the Service of Mankind, Sovetskly Patriot, Moscow,

June 22, 1966, p. 4.

57. Sivers, A. P., and Yu. I. Tarakanov, Kosmos i More, Leningrad: Izd-Vo "Sudostroyenyl",

1969, 87 pp.

58. Moscow Radio, April 1, 1968, 1400 GMT.

• Ms. Raleigh Is a physical sciences analyst In the Science Policy Research Division, Congressional Research Service, The Library of Congress.

ANNEX ONE

NAVIGATION SATELLITES

By Geoffrey E. Perry*

I. AN OPERATIONAL SYSTEM WITH A 74 ° INCLINATION

Kosmos 378 was the first satellite of this inclination to have an initial period of 105 minutes. This was placed in an elliptical orbit from which it has already decayed. The Soviet report to the 14th COSPAR session stated that it had performed ionospheric research. (1) Shortly afterwards, Kosmos 381 was placed in a near-circular orbit with a period of 105 minutes. Sven Grahn reported receiving ionospheric beacon-type signals in Stockholm and Geoffrey E. Perry found similar signals on a higher frequency in Kettering as well. A statement that "Kosmos 381 was probing the ionosphere" implied a top-side-sounder of the Alouette-Isis type, together with other techniques. (2) A full-scale model was displayed at the 1971 Paris Air Show. This was a cylinder 1.4 meters tall and 2.0 meters in diameter. The curved surface was covered with solar cells. Gravity-gradient stabilization appears to have been used with the long beam reaching up to the roof of the hall. For a satellite of this size equipped with solar batteries the transmitting life was exceptionally short, last signals being received in Kettering on January 30, 1971. Fears that absence of further signals was due to lack of perseverance in monitoring were dispelled by the Soviet report to the 15th COSPAR conference which stated that "Kosmos 381 studied VLF signals in the magnetosphere from December 2, 1970 to January 30, 1971. (3) It may be that other experiments continued functioning beyond that date, however.

Ten days after the launch of Kosmos 381, Kosmos 385 was placed into a similar orbit. No ionospheric beacon signals from this satellite were detected by the Kettering Group. This was followed at intervals throughout 1971 by Kosmos 422 and 465 and by Kosmos 475 and 489 in the early part of 1972. There have been no other launches of this type since then.

Table 6A1-1

List of Soviet Navigation Satellites at 74 degrees, 1970-1972

The position of the orbital plane in space relative to the fixed stars is specified by the right ascension of the ascending node or northbound Equator-crossing. For a given satellite the rate of change of right ascension remains fairly constant over long periods of time. It is therefore possible to compute values of right ascensions for given epochs if this rate of change and the value of right ascension at a fixed epoch are both known. In 1972, Perry employed this technique to show that these satellites are in orbital planes spaced at 120 ° intervals. (4) This is evident from the table given above which shows the values of right ascension for each satellite on the launch date of the last in the group. This configuration provides the rudiments of global coverage.

Moreover, it will be seen that the orbital planes of Kosmos 475 and 385 coincide, as do the planes of Kosmos 489 and 422. It is therefore reasonable to assume that Kosmos 475 and 489 replaced Kosmos 385 and 422 respectively after intervals of 440 and 350 clays, pointing to a useful payload life of about one year.

II. THE CHANGE TO 83 ° INCLINATION

An inclination of 83 °, the highest used to date by the Soviet Union, first appeared with the launch of Kosmos 480 into a 109 minute orbit on March 25,1972. Kosmos 514, also at this inclination, had a period of 104.4 minutes reminiscent of the 74 ° navigation satellites. It has been followed at regular intervals by Kosmos 574, 586, 627, 628, 663 and 689.

Using a graphical method, Perry and Ian Wildman of Kettering Grammar School were able to show that these satellites also had orbital planes spaced at regular intervals but that the spacing in this instance was only 60 °. (5) From their work it was apparent that Kosmos 627 had replaced Kosmos 514, Kosmos 689 had replaced 574, and that Kosmos 586 had been replaced in turn by Kosmos 628 and Kosmos 663.

Kosmos 700, launched at the end of 1974, did not fit the general pattern of replacement. Its orbital plane was offset from the main system by 20 ° to the east of Kosmos 627. Kosmos 726, the next member of the sub-set, was again offset from the main system and spaced 120 ° from Kosmos 700. The obvious gap in this supplementary system was filled by Kosmos 755, placed mid-way between these two. In the meantime Kosmos 729 had replaced Kosmos 627.

The launch of Kosmos 778 on November 4, 1975, signaled a new development. Offset 30 ° to the east of Kosmos 726, it marked the beginning of a transitionary phase toward 30 ° spacing's based on the supplementary system and the eventual disappearance of the original main system. Kosmos 789, launched on January 20, 1976 was the second of these and was placed midway between Kosmos 700 and 755, presumably replacing Kosmos 689.

III. THE RADIO TRANSMISSIONS

When Christopher Wood returned to the United Kingdom from Fiji, Perry encouraged him to try to identify the radio transmissions from this group of satellites.

Observations on 150 MHz, one of the frequencies known to be used by the U.S. Navy navigation satellites, suggested that this frequency was also used by the Kosmos satellites. Positive identification was made by showing that times of closest approach from Doppler measurements in Oxted, just south of London, showed a close correlation with predictions based on Goddard Space Flight Center two-line orbital elements. W. F. Blanchard has since established that these satellites also transmit on 400 MHz, another of the U.S. Navy frequencies. (6)

Wood was able to show that two types of signal, designated type A and type B for convenience, existed. Both types contain data at 50 bits per second but employ different modulation methods and bandwidths. The modulation methods result in sidebands symmetrically disposed around the 150.000 MHz carrier (U.S. Navy satellites use a frequency of 149.988 MHz to prevent operation near nulls on crossovers which would reduce accuracy). Type A has five pairs of sidebands at 3 kHz intervals spaced at 14 kHz from the carrier whereas type B has three pairs of sidebands at 2 kHz intervals spaced 3 kHz from the carrier. Wood has shown that this prevents mutual interference when signals are received simultaneously from two satellites, even allowing for opposite Doppler shifts.

His detailed analysis of the type B transmissions has shown that the telemetry frame consists of 60 words of 1 second duration, each containing 50 bits. Three different types of words are used. The first bit of each word occurs on an exact second synchronized with standard time transmissions from WWV. Bits 2-6 of each word form a block which decodes to give an hour count; bits 7-12 form a block which decodes to give a minute count and bits 13-18 decode to give a second count. The code is a development of the normal binary code —the difference between successive received bits giving the normal binary code. In tills way Perry and Wood have shown that the transmitted time is Moscow Time —GMT plus 3 hours.

The telemetry frame of the type A transmissions consists of only ten 1 second, 50 bit words of which the last three contain only time data. Moreover, only two different types of words are employed. It is of interest to point out that the main and supplementary systems disclosed by Perry and Wildman's analysis of orbital plane position correlate exactly with the type A and type B signals distinguished by Wood.

A third type of transmission has been received from the latest satellite, Kosmos 778. Since it features the two-frequency f.s.k. (frequency shift keyed) modulation of type B rather than the four-frequency f.s.k. modulation of type A, it has been classified as type B'. Prelimi-

nary study suggests a basic 2 minute frame comprising two 1 minute frames of differing types, using all three types of word found in the type B transmissions. (7)

IV. CONCLUSION

The two fundamental requirements for an operational navigation satellite system —global coverage and standard time transmissions —have been shown to exist within a sub-set of the Kosmos program. The six-satellite system currently operational, with orbital plane spacings in parens is: Kosmos 729 (20 °) Kosmos 700 (40 °) Kosmos 689 (20 °) Kosmos 755 (40 °) Kosmos 663 (20 °) Kosmos 726, with transmission types in the sequence A B A ? A B. Signals from Kosmos 755 have still to be identified and are expected to be of type B. A seventh satellite, Kosmos 778, has recently been placed 30 ° beyond Kosmos 726 with a new type of transmission, type B', which would appear to mark the start of a transition to a 30 ° spacing between operational satellites. Kosmos 789 was placed midway between Kosmos 700 and 755 in the early part of 1976 and it is expected that Kosmos 663 will soon be replaced by a satellite spaced 30 ° from Kosmos 755 and 726.

References:

(A) SOVIET SPACE PROGRAMS, 1971-75, OVERVIEW, FACILITIES AND HARDWARE MANNED AND UNMANNED FLIGHT PROGRAMS, BIOASTRONAUTICS CIVIL AND MILITARY APPLICATIONS PROJECTIONS OF FUTURE PLANS, STAFF REPORT , THE COMMITTEE ON AERONAUTICAL AND SPACE .SCIENCES, UNITED STATES SENATE, BY THE SCIENCE POLICY RESEARCH DIVISION CONGRESSIONAL RESEARCH SERVICE, THE LIBRARY OF CONGRESS, VOLUME – I, AUGUST 30, 1976, GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976,

1. Shtern, M. I., Investigations of the Upper Atmosphere and Outer Space Conducted In

1970 In the U.S.S.R. (translated by NASA in 1972). p. 28.

2. Soviet News, January 12, 1971.

3. ————. Investigation of the Upper Atmosphere and Outer Space Conducted in 1971 In the U.S.S.R. (translated by the Joint Publications Research Service in 1972). p. 29.

4. Perry, G. E.. Flight International. London. IDS, 7S8a-790, November 30, 1072.

5. Perry, G. E., and C. D. Wood. Journal of the British Interplanetary Society, S9, 307-316, 1976.

6. Blanchard, W. F., private communication.

7. Wood. C. D., private communication.

* The late Mr. Perry was senior science master at the Kettering Grammar School, Kettering, England.

Twelve percent of Russia's orbital missions during 1993-1994 were devoted to the fields of navigation and geodesy, bringing to more than 150 the number of Soviet/Russian navigation and geodetic spacecraft placed into Earth orbit since 1967. By the end of 1994, the Russian navigation satellite network consisted of 25 principal spacecraft in three distinct constellations to service both fixed and mobile subscribers. The geodetic network, on the other hand, includes only 1-2 active spacecraft, two specialized laser reflector satellites, and a larger number of host spacecraft carrying small laser reflectors.

The LEO navigation satellites are launched one at a time by Kosmos boosters from the Plesetsk Cosmodrome into orbits of approximately 960 km by 1,015 km with an inclination of 83 degrees. Each spacecraft has a diameter of 2 m, a height of approximately 3 m and a mass of 800 kg. An internally pressurized compartment housing the primary payload (approximately 0.86 m in diameter, 0.55 m in height, mass of 200 kg) and support systems is surrounded by solar cells affixed to a cylindrical sheet. Electrical power available to the payload is limited to about 200 W average daily (References 439-440). Attitude control is achieved with a 10-m gravity-gradient boom extending from the top of the spacecraft, while payload and telemetry antennas are attached to the bottom, Earth-facing end.