Soviet NAVSATs 1976-1980
NAVIGATION SATELLITES
While navigation help from satellites is likely to become a universal service for many classes of ships and aircraft, the early uses of such systems have been military, and the sponsorship of flights has been military. In the United States, the Transit system was de veloped by and for the Navy, becoming an essential element in the Polaris submarine and missile system. Later Transit was withdrawn from public discussion during the period when the U.S. De partment of Defense operated under the greatest restrictions on public information. The U.S. system is now declassified and made available to civilian users.
The Soviet navigation system was advertised by the Russians as in operation as long ago as 1966 but no Russian satellite was specif ically identified as having such a mission until the launch of Kosmos 1000 on March 31, 1978. Although no separate and distinc tive name, such as Meteor and Molniya, has been given to later satellites in the series, a model of Kosmos 1000 was diplayed at the 1979 Paris Air Show at Le Bourget under the name of Tsikada. Be cause the Russians also have long range submarine launched missiles, they probably used their system also to support submarine operations, and by now may be using them more widely, as does the United States. One is encouraged in this interpretation of how Soviet navigation satellites were first used when one notes the Rus sian Yankee class nuclear-powered submarines carry 16 launch tubes so closely copying the American Polaris and Poseidon classes.
Many proposed civil navigation systems discussed in the open lit erature involve an interaction two ways between the ships and air craft being navigated and the satellites in space. Typically, the mobile ship or aircraft sends a signal which is received by several satellites, and they relay the signal to a ground computer which compares signal differences, computes a position for the mobile ship or aircraft, and this position information is relayed back via a satellite to the mobile ship or plane. Such navigation systems not only have moderate costs for the mobile unit but also can serve to support traffic control purposes as well.
The early military navigation systems are different in concept from the system just described. In general, it is better for the mobile ship to remain radio silent, not to disclose its position. Sub marines in particular rely upon concealment, and at worst want to do no more than stick out of the water an unobtrusive receiving antenna to pick up satellite signals. The Transit system has been described as consisting of satellites in polar orbit which broadcast on 150 MHz and 400 MHz holding to these frequencies with great precision. The listening submarine or ship measures the Doppler shift of signals to determine the relative positions of listener and satellite. The satellite periodically give an accurate and updated set of emphemerides for its own position. Then a computer on the lis tening vessel combines the Doppler shifts in the harmonic signals and the position information on the satellite (fed in by satellite ground tracking stations) to calculate the position of the listener. This permits accurate locations to within a very few meters. Such a system with its accuracy helps the submarine or other ship to navi gate, and to keep an update on missile target locations. The trade press has reported that the same system can be used for tactical fire controllers in ground warfare as well. By using satellite navi gation data and the same grids, a fire controller out of view of a gun battery can still give directions permitting the very accurate placement of artillery rounds on selected targets.
Although the Russians have not described their system, the same compelling circumstances have applied, and observations by Wood and Perry of the Kettering Group confirm that they went along the same technical route as the Americans. 158
Whereas the United States developed Transit first for use with its Polaris 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 neces sary receiving equipment and computers which permit the use of the data on satellites, from which ship position may be derived, the Soviets have not yet adopted such an open posture.
soviet references to navigation satellites
Leonid Sedov stated as early as 1965 that space was already being used for communications, weather reporting, and precise maps of the world. 159 In January 1966, the new 5-year plan made specific reference to using space for communications, weather reporting, and navigation. 160
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 op eration." 161 He repeated similar words at a meeting of the Soviet Academy of Sciences held June 27, 1966. He made similar state ments in April 1967, and in November 1967. 162
One of the most explicit references to Soviet navigation satellites appeared in 1966 in a magazine article which stated that the preci sion of such devices is constantly improving as reference points for shipboard and aircraft navigation systems. Coordinates can be de termined to an accuracy of 200 meters. 163 A short book devoted to the subject was issued in 1969. 164
A 1968 broadcast mentioned a proposal for an air and ship navi gation 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. 165
Also, as mentioned elsewhere in this study, in connection with the launch of eight satellites by one launch vehicle on April 25, 1970, an article in Red Star hinted vaguely at the uses of such mul tiple launchings—for science, communications, and navigation; watching ionospheric processes; and radio astronomy by the inter ferometer 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 rather than forming a navigation system.
The launch of the 1000th satellite in the Kosmos series on March 31, 1978, produced a more than usually explicit announcement from the TASS News Agency.
The Kosmos 1000 satellite which was orbited on March 31 starts a new direction in the extensive utilization of space technology for the national economy. The speciality of new satellite is sea navigation.
Traffic on sea lanes is steadily increasing, and in order to ensure safety there is a need for more efficient naviga tional information.
Traditional coastal services and even global ground sys tems have a number of shortcomings, one of them being that they are dependent to a large extent on the weather. Navigation by stars, which had been used by seafarers since time immemorial, also depends on weather condi tions.
Space radio beacons open up new horizons, providing the opportunity to establish a global all-weather system for navigation which will be highly accurate. The satellite con stantly sends out signals of a definite frequency. These are received by ship serials and enter an electronic computer for processing.
In establishing the coordinates, use is made of the Doppler effect. The frequency of the signals changes because of the speed of the satellite. Using these data an "electronic navigator" can produce navigational information in a convenient form—geographical coordinates and precise astro nomical time. This makes it possible to automate ship navigation to a very large extent.
Together with Molniya and Meteor satellites which ensure trouble-free communications through outer space and efficient transmissions of weather reports, navigation satellites will help enhance considerably the effectiveness of the use of the sea fleet and ensure the safety of naviga tion in all parts of the world ocean. Geodesists and geolo gists, for whom astronomically accurate coordinates are also of great importance, have long been dreaming of such apparatuses.
An article explaining in detail how to use the Transit system to determine ship position, claimed that when the elevation of the satellite from the ship was between 26° and 66°, an accuracy of be tween 60 and 130 meters was attainable. 166 It is worthy of comment that, as recently as 1975, a Soviet writer was still describing the American system.
navigation satellite systems
The position of the orbital plane in space relative to the fixed stars is specified by the right ascension of the ascending node, R.A., or northbound Equator crossing. For satellites in near-circular orbits at 1000 km altitude, the rate of change of R.A. remains rea sonably constant over long periods of time, and thus it is possible to compute values of R.A. at given epochs from known values of R.A. at two widely separated epochs.
By computing the R.A.s of operational satellites at an epoch close to the launch-date of a new satellite, it is possible to observe the relative orbital plane spacings and note which satellite has the same R.A. as the newcomer. It is not unreasonable to assume that this satellite has been replaced at the end of its operational life, and decoding of radio transmissions given the satellite's identity number by the Kettering Group since 1976 confirms the assump tion.
THE FIRST OPERATIONAL SYSTEM
In 1972, Perry employed the orbital plane spacing technique to show that five satellites placed in near-circular orbits at 74° orbital inclination with orbital periods close to 105 minutes had their planes spaced at 120° intervals, thus giving rudimentary global coverage by three satellites. 167 Table 36 gives the R.A.s of these satel lites at epochs close to their launch dates. The satellites fall into three groups with their R.A.s spaced at 120° intervals. Moreover, it will be seen that Kosmos 475 and 489 replaced Kosmos 385 and 422. The intervals between replacements of 440 and 350 days re spectively point to an operational life of about 1 year.
THE SECOND OPERATIONAL SYSTEM
Kosmos 514, launched on August 16, 1972, differed from these five satellites only in having an inclination of 83° instead of 74°. In 1973 it was joined by Kosmos 574 at an orbital plane spacing of only 60°, followed 3 months later by Kosmos 586 a further 60° away. These were followed at regular intervals by Kosmos 627, 628, 663 and 689, all of which were placed into the same orbital planes as the first three. Orbital plane spacing analysis dispelled the belief, held in some quarters, that Kosmos 628 was an immediate replacement for Kosmos 627 which had failed in its mission—their planes were 120° apart. Table 37 shows the replacement sequence of this second operational system of navigation satellites.
A major change occurred on February 3, 1976, with the launch of Kosmos 800. Instead of directly replacing Kosmos 663, it was placed in a plane separate from that of Kosmos 663 by 180°. This had the effect of moving the orbital planes of the second operational system away from those of the third system, which had been introduced at the end of 1974 and was being extended to a six-satellite system.
The near-polar inclination of 83° meant, in effect, that satellites in orbital planes spaced 180° apart were virtually in the same or bital plane but traveling in opposite senses. Thus it was only necessary to cover an arc of 180° with the orbital planes to achieve com plete global coverage.
THE THIRD OPERATIONAL SYSTEM
Kosmos 700, launched at the end of 1974, did not fit the general pattern of replacement for the second operational system, being offset by 20° from Kosmos 627. Kosmos 726 was also offset from the second system and was 120° away from Kosmos 700. The gap in this third system was filled by Kosmos 755, placed midway between them. When Christopher Wood undertook his search for the radio transmissions from these satellites, he was unaware of the separate systems discovered by Perry and Ian Wildman at Kettering. Consequently, he was perturbed to discover two different types of modu lation on 150 MHz which he designated types A and B. Further confirmation of the existence of separate systems came from the subsequent correlation of type A signals employing frequency-shift keying, f.s.k., between five sidebands with satellites of the second operational system and type B signals employing f.s.k. between three sidebands with satellites from the third operational system. 168 The type B' signals reported in that paper and in annex 1 to chapter 6 of the 1975 report, Soviet Space Programs, 1971-75, were later found to be type B with empty parameter blocks in the 2d minute of each 2-minute frame.
The launch of Kosmos 778 on November 4, 1975, signalled a further development. Placed midway between Kosmos 726 and 775, it marked the growth of the third operational system into a six-satellite system with orbital planes spaced at 30° intervals.
Wood's discovery of identity numbers within the telemetry from these satellites eased the problem of determining which satellites were really operational and revealed that certain satellites re mained operational for some time after their replacement had been launched. This is only to be expected as a replacement would be launched before a satellite degraded to the point of failure and not after it had failed, unless failure was unpredictable, as was the case of Kosmos 1064.
Kosmos 1064 was launched as a replacement for Kosmos 991 in December 1978. 169 It failed to circularize its orbit and remained in the 99 min elliptical transfer orbit. Nevertheless, it was given the identity No. 1 and transmitted data for a time. It was in turn replaced by Kosmos 1072, with identity No. 8, in January 1979.
Despite this failure and subsequent early replacement, Kosmos 1064 was found, by David Wilson of Kent, OH, to be transmitting "time only" data during October, November and December 1979. Table 38 shows the replacement sequence of third operational system, which is still in use at the time of writing.
The identity numbers found in bits 19 through 23 of the third word in the parameter blocks, transmitted in the second half of each minute, are not unique and originally related to a particular satellite only during its operational lifetime. They were then reallocated to replacement satellites but, until mid-1979, no replacement took the identity number of the satellite it was replacing. Identity numbers are given in parentheses following the Kosmos numbers in table 36.
1979—probably around the time of launch of Kosmos 1141 on October 16, 1979. This led to a logical sequency of numbering, from 1 through 6, in orbital-plane position round the Equator. Since then, replacement satellites have assumed this logical number and the satellite being replaced has been renumbered 7 or 8 for the remainder of its operational life.
AN OPERATIONAL SYSTEM FOR CIVIL USE
Kosmos 883 was placed in one of the six groups of the third oper ational system and had its ascending node in the opposite hemi sphere. Although its signal format was type B it carried the identi ty No. 11. Nos. 9 and 10 have never been observed. It was followed by Kosmos 926 with an identity No. 12 and ascending node 45° away from that of Kosmos 883 in the hemisphere opposite to that of the third operational system. All became clear with the launch of Kosmos 1000 a further 45° away and No. 13. This was the first Kosmos satellite to be specified as performing a navigation mission and references to civil usage strongly suggests that satellites with identity numbers of 11 and upwards form a civil system. This hy pothesis was strengthened by the launch of Kosmos 1092, No. 14, a further 45° away, completing a four-satellite system with orbital planes spaced at 45° intervals giving complete global coverage. The development of this system is given in table 39. Identity numbers are given in parentheses following the Kosmos number.
Kosmos 1179 has been included because some analysts have been tempted to consider its elliptical, 103.6 min., orbit as a failed ele ment of a navsat system. Table 39 shows that it was placed precise ly 30° out of plane with Kosmos 1168 and this was 15° away from Kosmos 1141 in the gap between the third operational system and the civil system. We do not consider it to be a failure but rather to be carrying out some unspecified mission other than navigation.
description of the kosmos navigation satellite
The first satellites with an orbital inclination of 74° and orbital period of 105 minutes were both reported to be performing scientif ic research related to the ionosphere. 170 171 Kosmos 378 had an el liptical orbit from which it decayed naturally within 2 years. Since Kosmos 381 was placed into a near circular orbit only 2 weeks later it may be speculated that a similar orbit was intended for Kosmos 378 but not achieved. A full-scale model of Kosmos 381 was dis played at the 1971 Paris Air Show. This was a cylinder 1.4 meters tall and 2.0 meters in diameter. Gravity-gradient stabilization was used with the long boom reaching up to the roof of the hall. The curved surface was covered with solar cells. Perry 172 speculated that the navigation satellites in the Kosmos series would be similar in appearance and dimensions. This speculation was substantiated when a full-scale model of Kosmos 1000 was displayed in 1979. The major modification was an increase in the height-to-diameter ratio. The ionospheric probing antennas were also omitted. Figure 47 shows drawings of the Kosmos 1000 and 381 satellites, not both to the same scale. The gravity-gradient stabilization boom is unfurled to its full length from the disc-shaped housing mounted in the trussed structure attached to the hemispherical end of the inner cylinder.
NAVIGATION
Kosmos satellites for navigation continued to be launched at varying intervals. Five were launched during 1981, eight in 1982 and seven in 1983. Of these, one only in 1981 and two in each of the other years were replacements for satellites in the civil system with a constellation of four satellites at 45° orbital plane spacing, confirming an impression of generally increased longevity and the possibility of a lower order of priority and/or precision for these by comparison with the constellation of six at 30° plane spacing believed to have a military role. Tables 4 and 5 give details of these satellites and those they have replaced by identity number within each category.
2. Kosmos 1383 and Kosmos 1447 also carried Kospas searcti and rescue equipment.
Kosmos 1275 fragmented after 50 days in orbit—a unique occurrence for a navigation satellite. It is difficult to account for the fragmentation in view of the fact that models of Kosmos 381, Kosmos 1000, and Kospas displayed in public at the Paris Air Show no sign of a propulsion or an orbit correction system which might have been the cause. Johnson pinpoints the time of fragmentation as 2351 GMT on July 24, 1981, and does not exclude the possibility of the fragmentation being due to a collision with another object. (52)
Kosmos 1304 apparently suffered from an under-burn of the final stage and entered an orbit with a period of 104 minutes rather than the intended 105 minutes. As a result of the differing rates of precession of the ascending node, the plane spacing of the civil system steadily degraded until Kosmos 1304 was replaced as No. 12 in 1983 by Kosmos 1506. This restored the 45° plane spacing. The delay in replacing Kosmos 1304, which was electronically satisfactory, is a further indication of the lower priority attached to the civil system.
Another, far more serious, final stage under-burn resulted in Kosmos 1380 being placed in a 93.1-minute orbit with a 140 km perigee from which it decayed naturally after 9 days. It was quickly replaced by Kosmos 1386 as a replacement for the aged Kosmos 1225.
Between these two launches came Kosmos 1383, the first satellite to carry Kospa: search and rescue equipment. It was joined in 1983 by Kosmos 1447, also with Kospa: equipment, and the American NOAA 8 satellite which carried Sarsat equipment.
Kosmos 1506 ceased operating around December 14, 1983, and the civil
system was temporarily reduced to only three satellites. However, by February 15, 1984, it was once again operational.
Following its replacement by Kosmos 1428, Kosmos 1333 took on identity No. 7 and has retained this even following the replacement of Kosmos 1428 early in 1984. Identity No. 8 has not been reallocated to any replaced satellite since Kosmos 1181, which ceased operating in mid-1983. (53) It may be that the practice of reallocating identities is being discontinued.
The first of the GLONASS test vehicles appeared as a surprising triple D-l-e launch at 51.6° with a plane change to 64.8°. Kosmos 1413, 1414, and 1415 were not spaced at 120° around the orbit as with the American GPS Navstar test satellites, but drifted slowly apart from a common injection point. However, Kosmos 1414 did appear to make a small inorbit maneuver suggesting some propulsion capability.
The second launch in the series, on August 10, 1983, placed Kosmos 1490, 1491, and 1492 into the same orbital plane as the first three satellites, but the third launch, on December 29, 1983, put Kosmos 1519, 1520, and 1521 into a plane separated by 120° from the first six. In all cases the final orbits fell short of the completely semisynchronous 717.7 minutes and this is now felt to have been intentional rather than a systematic failure to achieve a desired set of orbital parameters. Any in orbit maneuvers have been small and it can be presumed that the system is still in the development and testing stages.
References:
A. SOVIET SPACE PROGRAMS: 1976-80 (WITH SUPPLEMENTARY DATA THROUGH 1983), UNMANNED SPACE ACTIVITIES, PREPARED AT THE REQUEST OF Hon. JOHN C. DANFORTH, Chairman, COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION, UNITED STATES SENATE, Part 3, MAY 1985, Printed for the use of the Committee on Commerce, Science, and Transportation, 99th Congress, 1 st. session, COMMITTEE PRINT, S. Prt. 98-235, U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1985
52. Johnson, op. cit., pp. 16-17.
158 Wood, C.D., and G.E. Perry, Phil. Trans. R. Soc. Soc. London A., vol. 294, 1980, pp. 307-315. The section of this paper describing the coding of the telemetry is reprinted by permission of the Royal Society as the second annex to this chapter.
159 Tass, Moscow, Dec. 31, 1965, 1612 G.m.t.
160 Tass, Moscow, Jan. 5, 1966, 1130 G.m.t. lei Pravada, Moscow, Apr. 3, 1966.
162 Moscow Radio, Apr. 12, 1967, 1355 G.m.t.; Moscow Radio, Nov. 5, 1967, 0905 G.m.t.
163 Nadezhdin, D. Space Science in the Service of Mankind, Sovetskiy Patriot, Moscow, June
22, 1966.
164 Sivers, A.P., and Yu. I. Tarakanov, Kosmos i More, Leningrad: Izd-Vo "Sudostroyenyi,"
1969. ' '
165 Moscow Radio, Apr. 1, 1968, 1400 G.m.t.
166 Referativnyy Zhurnal 51 Astronomiya' Otdel'nyy Vypusk, No. 8, 1975, 8.51.160.
187 Perry, G.E. Flight International, London, vol. 102, Nov. 30, 1972, pp. 788a-790.
168 Perry, Q.E., and C.D. Wood, Journal of the British Interplanetary Society , vol. 29, 1976; pp. 307-316.
169 Flight International, London, vol. 115, Feb. 24, 1979, p. 515.
170 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.
171 Soviet News, Jan. 12, 1971.
172 Perry, G.E. R.A.F. Qy., vol. 18, 1978, p. 278.
