1st. & 2nd. Generation Photo Recons
ANNEX TWO
RECOVERABLE KOSMOS SATELLITES FOR MILITARY RECONNAISSANCE
By Geoffrey E. Perry*
1971-1975
I. LAUNCH STATISTICS
On March 16, 1962, the Soviet Union initiated the Kosmos program "to continue the study of outer space". When it was announced that Kosmos 4 had been recovered from orbit after a flight of only four days it was clear that the name Kosmos was a blanket-term covering a variety of missions. A systematic study of the orbits, launch-times, launch-sites, locations of perigee, flight duration, and routine monitoring of short-wave radio transmissions, such as has been carried out at Kettering Grammar School since 1962, reveals distinct sub-sets, the largest of which contains those satellites which disappear from orbit when their orbital period is still high enough to rule out natural decay.
At the time of the launch of Kosmos 250, nearly 47 per cent of all Kosmos launches fell in this category. This proportion rose to over 50 per cent by the launch of Kosmos 350 but, with the change to longer duration flights, it decreased once more and, at the end of 1975, it stood at 47.19 per cent. Another way of looking at the statistics reveals that during 1975 at least one member of this subset was in orbit for 86.3 per cent of the time, two or more were in orbit simultaneously for 26.6 per cent of the time, and three in orbit for 11.0 per cent of the time.
Initially all such launches originated from Tyuratam but since the first launch from Plesetsk, in 1966, the majority of such launches have been made from there and in 1975 Plesetsk launched 22 of the 34 payloads in this sub-set.
II. MISSION PROFILE
These satellites are launched by the A-vehicle in either its A-l or, nowadays, A-2 configuration. Injection into orbit occurs some 9 minutes after lift-off and, when ionospheric conditions produce favorable propagation, short-wave radio signals can be received at this time.
Transmissions of this type are not continuous but cease after a predetermined time. They commence once more when commanded as the satellite rises above the horizons of Soviet ground-stations. In general they are not commanded-on for passes which do not take them directly over Soviet territory and it is not unusual, these days, for certain passes which do go over Soviet territory to fail to produce short-wave signals. As described later, VHP transmissions are commanded-on when the satellite is well above the horizon of the ground-station.
The first generation satellites utilized a switching sequence towards the end of their final transmitting pass of the day but this is rarely observed nowadays. (1) When a second satellite is to be launched during an uncompleted mission, the transmission frequency of the first satellite is changed by 2n Hz, where n Hz is the amount by which it is offset from either 19 MHz or 20 MHz, whichever is the nearer, in the first instance.
Throughout the final orbit before recovery the short-wave transmitter transmits continually, although Wakelin's observations in Cyprus have recently suggested that this may no longer be true. The round-the-whole-orbit transmission was established by Wood's observations from Fiji supplemented by early-morning observations during the mid-summer months in Kettering.
As far as one can tell, all payloads have been recovered on a north-bound pass, including Kosmos 231, 720 and 759 which were recovered in darkness. An explanation for this is to be found in the recovery technique described for the manned Vostok spacecraft. While over Africa the position of the spacecraft was automatically orientated so that the vector of the retro-thrust was in the correct direction relative to the orbit. Doubtless optical sensors were used for this purpose and therefore sunlight was essential for their operation. Al-though these three satellites landed in darkness, retro-fire would have been in sunlight.
Wood's reception of signals from Kosmos 199 in Fiji indicated that recovery was planned on the eighth day and, although the payload was exploded the short-wave transmitter continued in orbit with a reduced period and transmitted until it decayed naturally several days later. Another recovery failure occurred in 1973 when Kosmos 554 was exploded just before the transmitter, which had operated continually following the abortive reentry attempt, failed due to exhaustion of the chemical batteries. (2)
Details of recovery and the signals received at those times are given in Section V of this Annex.
III. PHOTOGRAPHIC COVEBAGE
Our first indication that these satellites might be more concerned with the collection of intelligence rather than the transmission of previously garnered data came during our second study of a satellite of this sub-set, Kosmos 15, in April 1963. We observed that it did not transmit on revolutions 19, 35, 51 and 67 when it was passing north-bound across Great Britain. (3) I believe that, at about that time, the BMEWS (ballistic missile early warning system) station at Fyling-dales was being commissioned.
By plotting the ground-tracks of the orbits over a given area for the whole duration of the mission it was possible to show that, in eight days —the normal duration for the first generation satellite —complete photographic coverage was obtained. The ground-track drifted slowly westward day-by-day until, on the eighth day it once again occupied the first-day's position. (4) There was also a correlation between launch-times and sunset-times in the northern hemisphere pointing to a desire to maintain some uniformity of lighting conditions. (5)
Complete photographic coverage for a non-manoeuvring mission is obtained with orbital periods given by T=518,400n/(16n ±l) (360.98+8.95 cos i) minutes where n = length of mission in days; i= inclination of orbit to the Equator; and the sign is taken as — for orbits with a daily westward draft and + for those with i = 81.3 ° which drift eastward.
This leads, in general, to greater orbital periods for flights at higher inclinations; for 12-day missions at 62.8 ° and 72.8 ° the periods evaluate as 89.23 and 89.58 minutes respectively. Reference to the complete table of launches in Appendix A to Volume 1 of this report will enable the reader to verify this for himself, even in the case of maneuverable payloads which could be expected to provide complete coverage if the maneuvering engine should fail in orbit.
The trend toward longer duration is a direct corollary of a general improvement in resolution. Obtaining better resolution on the same film format by use of longer focal length lenses results in a smaller ground area being photographed. The more closely spaced ground-
tracks and consequent lower period of the longer missions is obtained by lowering the apogee. Perigee heights have always been as low as practicable consistent with keeping air-drag to an acceptable minimum.
Examples of complete coverage for non-manoeuvring missions are given in Figs. 6A2-3(d) and 6A2-4 for Kosmos 599 and 759 in Section VI of this Annex.
IV. RADIO TRANSMISSIONS AND TELEMETRY FORMATS
The first signals from one of these recoverable missions received in Kettering originated from Kosmos 13 early in 1963. It was immediately apparent that a type of modulation different from that previously encountered was being employed. Until then, all short-wave signals from the first Korabl Sputnik and the non-recoverable Kosmos 1 and 5 had been simple on-off keying of the carrier wave. The Kosmos 13 signals were frequency-shift keyed (f.s.k.) with the "off" periods being transmitted on the second frequency. The telemetry frame format was the same as that of Korabi Sputnik 1 —a characteristic "purr" due to a synchronizing train of rapid pulses followed by 15 words, or bleeps, transmitted at a rate of approximately one word per second. Removal of one of the two frequencies by adjusting to zero-beat conditions revealed that these words were pulse-duration modulated (PDM), the length of each audible "bleep" being a measure of some parameter onboard the satellite. (6)
A more detailed investigation by Flagg of the Soyuz 3 telemetry showed that the on-off transitions of these words all fell in a null in the square-pulse train used to synchronize the ground decommutator with the onboard commutator. He also showed that the combined on-off time of each word was defined by 32 pulses, although only 29 pulses are transmitted, and suggested that the telemetered values were quantized in 32 permitted durations. It will be seen that the 32 or 2 (5) permitted values can be represented by a 5-digit binary code for digital storage and computer analysis. It is possible that values are logarithmically amplified before quantization.
It was found that the first word of the frame following the synchronization pulses existed in several modes. (7) During the main part of the mission it took values of 23 or 9 which came to be referred to as mode 1 and mode 2. A third mode of value 16 was observed immediately prior to recovery. Later, a fourth mode of value 30 was discovered and it was established that the recovery modes 3 and 4: are associated with modes 2 and 1 respectively, the change occurring at the instant of recovery capsule separation from the instrument package. Words 7, &, 12, 14 and 17 also change at this time.
These modes provided a means of classification into mode 1 only, mode 2 only and mode-changers —those for which word 1 was observed to change from mode 1 to mode 2 in mid-transmission. Mode 1 only has been used to classify low-resolution missions in Table 6-11 whereas mode 2 only and mode-changers are classified as high resolution. The change from mode 1 to mode 2 only occurred when the satellite had risen well above the horizon of a principal ground station on Soviet territory, suggesting that the change was due to line-of-sight rapid play-back of stored intelligence on another frequency —VHF or UHF.
The introduction of the manoeuvring capability coincided with the appearance of a new type of transmission in the form of Morse code groups. Although this was first identified in Kettering during the flight of Kosmos 280 it would seem that signals were received from Kosmos 264 but ignored and logged as interference. As the number of such missions increased so our understanding of these transmissions grew. Twelve groups of three Morse code characters were transmitted repetitively at a rate well within the reading capability of a
competent radio amateur. With one exception the groups were formed by characters chosen to give a total of seven pulses per group in a 2-3-2 configuration; for example, MWI —2 dashes, 1 dot and 2 dashes, 2 dots. The other group was formed by characters giving a total of seven pulses in a 3-1-3 configuration. It is assumed that this 3-1-3 group served as a reference denoting the first of 12 parameters. A typical sequence from Kosmos 280 is as follows:
STS MOM IDN NGM MGN MWI NUN MWM AUA MOM NOA NKI
Initial attempts to interpret these groups as binary code were not encouraging as changes in groups appeared to be random. Study of the seventh, however, which changed continually throughout a mission, showed that they were indeed binary code but the first digit rather than the last took the value 2" —the digits were read in the reverse direction to that used conventionally. If a binary 0 was assigned to each dot and a binary 1 to each dash, the seventh word was found to increase steadily throughout the mission. This was 7-bit pulse code modulation (PCM).
The sixth group was invariably MWI at the beginning of a mission, changing to MRI at the same time as the manoeuvring engine was discarded and thus indicating the probability of recovery on the following day. The 14-day flight of Kosmos 399 was probably extended at the last minute since the change to MEI occurred as usual on the 12th day whereas recovery did not take place until two days later.
The steady change in value of word 7 in the PCM frame and of word 13 in the PDM frame showed the usage of some consumable. The choice between attitude stabilization gas and photographic film was resolved in favour of the latter when Kosmos 463 was observed to use up this consumable at twice the normal rate in its half-the-normal-duration mission at the time of the Bangladesh war.
Transmission frequencies for these types of telemetry were 19.994 MHz for PDM and 19.150 MHz for the PCM Morse code. At times when two satellites of the same kind were in orbit simultaneously it was observed that the transmission frequency of the first was changed
to enable the second to operate on the main frequency. PDM's changed to 19.989 MHz and PCM's changed to 19.300 MHz. Word 14 of the PDM frame changed from a value of 23 to 16 at this time.8 On occasions this m-flight frequency changing alerted us to the probability of an ensuing launch and in the cases of Kosmos 240 and 345 suggested that their launches had been unavoidably postponed for 24 hours.
A new feature of the PDM types appeared following the general increase in duration to 12 days. Sven Grahn discovered that these extended-duration types also transmitted broad-band VHP signals on frequencies close to 66 MHz. The change from 8 to 12 days duration was accompanied by a relocation of the very high value in the 15-word PDM telemetry frame from llth to 7th position. It was later observed that certain flights did not have this very high value at all initially but, toward the end, word 7 assumed this very high value at the same time as additional pieces appeared in orbit. Mode 1 satellites can now be divided into two groups: those for which word 7 is very long throughout and those for which it lengthens near the end of the mission. It has been shown9 that the latter category contains those for which the Soviet reports to the annual COSPAE meetings assign scientific missions. These are the 3rd Generation Low Resolution PDM-Science types shown in Table 6-11.
Yet another type of f.s.k. transmission was discovered during the flight of Kosmos 364. In this type there appears to be no telemetry and the 19.989 MHz transmissions must serve as a tracking beacon on each frequency alternately for approximately 0.75 seconds. Recently, Wakelin has pointed out that the total cycle period varies from satellite to satellite whilst remaining close to the general 1.5 second period. It may be that this will provide yet another means of classification but that remains to be established. This transmission is duplicated on 39.98 MHz but the two transmissions are commanded on separately. A more positive method of classification is by frequency. A special sub-set of these satellites transmit on the 19.994 MHz of the PDM satellites and study of the orbital parameters shows that they do not manoeuvre. It appears that these are taking over the role of the PDM low-resolution non-science payloads, the last of which, Kosmos 751, was launched last July.
V. RECOVERY BEACONS
Following the loss of the PDM transmission from Kosmos 114 as the instrument package burned up on reentry, Sven Grahn recorded a continuous sequence of Morse code TK groups on 19.995 MHz. At the time we attached little importance to this, doubtless because they had not been heard before due to cessation of monitoring following the loss of the PDM transmission. However, later in 1966, a similar transmission was recorded in Kettering following recovery of Kosmos 126 when the receiver was left switched on. This seemed too much of a coincidence and special attention was paid to recovery of Kosmos 127. TK's were recorded once again in Kettering.10 As time went by it became clear that these signals originated from the recovery capsule and were intended to assist recovery teams in locating the payload. The mean interval between loss of the PDM transmission and the onset of TK's was 6.75 ± 0.5 minutes. The TK transmission begins at the instant the parachute is deployed. An abrupt decrease in strength some seven or eight minutes later indicates the time of touch-down. The length of time for which these TK's persist after this is a measure of the precision of the recovery. There have been occasions when the TK signals have ceased abruptly in less than seven minutes without a prior decrease in intensity which raise the possibility of mid-air recoveries.
Pen-recordings reveal that the dash of the T has twice the duration of the dash in the K. Nevertheless such signals have become known as TK's "within the trade". Horst Hewel, of West Berlin, pointed out that TK's were sometimes transmitted simultaneously on both 19.995 and 20.005 MHz.
As time went by other beacons were observed. TG's were transmitted on 20.005 MHz by mode 1 only satellites. TF's became the trademark of the 3rd Generation High Resolution 2-tone Manoeuvrable class with TL's transmitted by the special sub-set classified as 3rd Generation Low Resolution 2-tbne Science in Table 6-11. The common factor of the "T" in all of these is justification for placing the T first in each pair —a happy initial choice.
TK's having a longer duration cycle than usual were observed in 1970 persisting for quite long periods on days when no Kosmos recoveries took place. It has been suggested that these originated from practice recoveries for the return capsule of Luna 16." This might also explain the TK's received during the flight of Kosmos 301. It is now believed that these originated from tests for recovery of a lunar return capsule prior to the launch of Kosmos 305, a case of presumed failure of a lunar probe to leave Earth-orbit.
N"0 explanation is offered for TVs which have been heard on occasions.
The reappearance of TK's with the recovery of Kosmos 774 after an interval of rnore than a year following the phasing-out of the Morse code types was unexpected.
VI. IDENTIFICATION OF POSSIBLE TARGETS
The first opportunity to identify the particular target for one of the recoverable photographic missions arose in 1968, just prior to the introduction of the manoeuvring capability. The 149 km perigee of Kosmos 246 was the lowest ever used in the program and was located near 20 ° N, northbound. The launch on October 7, only four days before the planned lift-off of Apollo 7, seemed timed to provide passes in the vicinity of Cape Canaveral around local noon. The ground-tracks of these passes are shown in Fig. 6A2-1. Due to the extremely low perigee, the orbital period decayed quite rapidly from 89.3 minutes
at launch to below 89 minutes at recovery. This caused the spacing between corresponding ground-tracks on successive days to become closer as time went by. On October 11, Kosmos 246 flew by Cape Canaveral only 30 minutes after the Apollo 7 launch at 1100 EDT. It was recovered at the first opportunity on the following day after a flight of only five days. So confident were we of this early recovery that we were monitoring from 0500 GMT onward and, although no signals were received at Kettering, Grahn had the TK recovery beacon in Stockholm.
The value of the manoeuvring capability was demonstrated during the Indo-Pakistani war at the end of 1971. (12) Kosmos 463 was launched into an 89.3 minute orbit at 65 ° inclination from Tyuratam on .December 6 and passed over East Pakistan (now Bangladesh) on the follow-in"- day after 14 orbits at its perigee height of 205 km at 0638 GMT--for local Sun-time add six hours. Two orbits later, perigee was lowered to 188 km, reducing the orbital period to 89.0 minutes and causing the ground track to repeat itself on a daily basis. Such a ground-track which, in the case of reconnaissance missions, repeats itself after a further 16 orbits, may be said to be stabilized. Times of crossing East Pakistan on December 8 and 9 were 0622 and 0605 GMT respectively. In order to re-position the satellite for favorable recovery on December 11, apogee was raised after 48 orbits to produce an 89.3 minute period once again. The ground tracks are shown in Fig. 6A2-2(a). It is of interest that the Morse code telemetry revealed the use of consumables, presumably photographic film, at twice the normal rate for a 13-day mission,
FIGURE 6A2-2
FIGURE 6A2-2( a). —Ground tracks of Kosmos 463, from right to left, of revs. 14, 30, 46, 62 and 78 on December 7 through 11, 1971.
Meanwhile, on December 10, Kosmos 464 had been launched into a 90.3 minute orbit at 72.9 ° inclination from Plesetsk. This higher-than-usual period gave a westerly drift of ground-track of 5 ° per day bringing it over East Pakistan at 0510 GMT on December 13, after 44 orbits. The 213 km perigee was initially at 60 ° N but, two orbits later, a two-impulse manoeuvre lowered both apogee and perigee to produce an 89.0 minute period with a 182 km perigee at 20 ° N. The westerly daily drift was reduced to less than 1 ° per day permitting three further daylight passes over the area before recovery after 94 orbits on December 16. The ground-tracks are shown in Fig. 6A2-2 (b).
FIGURE 6A2-2(b). —Ground-tracks of Kosmos 464, from right to left, of revs. 12, 28, 44, 60, 76 and 92 on December 11 through 16, 1971.
The most intensive use of photographic reconnaissance satellites occurred during the Yom Kippur war in 1973. (13) When the war broke out on two fronts on October 6, Kosmos 596, launched from Plesetsk three days earlier, was already in orbit. However, this was a non-manoeuvrable, low-resolution type, providing only wide-area coverage. Within an hour of the outbreak of hostilities Kosmos 597 had been launched, again from Plesetsk. This was a high-resolution manoeuvrable satellite of the type which uses the two-tone short-wave tracking beacon.
On October 8, Kosmos 597 was suitably positioned to survey both battle areas and its apogee was lowered to produce a stabilized ground-track with perigee over the Middle East on the northbound pass. By this time the orbit of Kosmos 596 had drifted westward so that it was no longer able to cover the situation and it was recovered after a flight of only six days. Its ground-tracks are shown in Fig. 6A2 — 3 (a).
FIGURE 6A2-3 (a). —Ground-tracks of Kosmos 596, from right to left, of revs. 14, 30, 46, 62 and 78 on October 4 through 8, 1973.
Kosmos 598, a "Morse code" type, was launched on the following day from Plesetsk into an orbit of inclination 72.9 °. As can be seen from Fig. 6A2-3 (b), the 65.4 ° inclination of Kosmos 597 provided passes over both the Suez front and the Golan Heights. By this time, the battle for the Golan Heights was nearly at an end and the choice of the new inclination provided a photographic pass over the Middle East on the day after launch rather than on the third day of the flight. Kosmos 597 had been recovered after a six-day flight on October 12. Shortly after this the apogee of Kosmos 598 was lowered to produce a ground-track with a slow eastward daily drift as shown in Fig. 6A2-3(c).
FIGURE 6A2-3(b). —Ground-tracks of Kosmos 597, from right to left, of revs. 14, 30, 46, 62 and 78 on October 7 through 11, 1973.
FIGURE 6A2-3(c). —Ground-tracks of Kosmos 598, from right to left of revs. 15, 79, 63, 47 and 31 on October 11 through 15, 1973.
It had become the established practice to produce stabilized ground-tracks by a two-impulse manoeuvre. The first burn would lower perigee to around 175 km to provide the optimum photographic coverage at the desired latitude on the northbound pass, and the second stabilized the ground-track by lowering apogee. The reason for the change in technique can be understood when it is realized that at a height of 210 km —a typical perigee for the initial orbit of these photographic reconnaissance flights —a satellite is just visible from a ground-station 14.5 ° due north of the sub-satellite point, whereas if the height is reduced to 175 km the ground range falls to 13.25 ° of latitude, a difference of 140 km. The ground-station at Yevpatoriya in the Crimea lies on approximately the same longitude as Suez and only 15.25 ° to the north, so the Russians had the capability of real- time surveillance by sacrificing some degree of resolution which could be restored anyway by changing the focal length of the camera lenses.
The Middle East was not the primary target of Kosmos 599 which was launched from Tyuratam on October 15 with an inclination of 65.0 °. It was a non-manoeuvrable PDM satellite which flew for 13 days instead of the usual 12 and provided photographic coverage of the battle area only on the last three days of its mission. This was probably a low-resolution flight, mounted to augment the results from the truncated Kosmos 596 mission. Its ground-tracks are shown in Fig.6A2-3(d).
FIGURE 6A2-3(d) —Ground-tracks of Kosmos 599, from right to left, of revs. 112,128,144, 160, 176, 192,1 and 17 on October 15,16 and 22 through 27,1973.
Kosmos 598 was recovered on October 16 and immediately replaced by another "Morse code" satellite at the same inclination. This was the first day since the outbreak of the war on which there was no photo-graphic pass over the battle area. Kosmos 600 made its first pass on October 17 after 15 orbits. Its subsequent manoeuvres produced a unique pattern —an "Ali-shuffle" in space. Apogee was lowered on the second day causing the ground-track to drift slowly eastward, back across the battle area. Perigee was shifted to the southbound pass,
preserving a 215 km height over the battle area, northbound. Two days later, apogee was raised causing the ground-track to drift west-ward over the battle area once again. These ground-tracks are shown in Fig. 6A2-3 (e). It was recovered on October 23 after a flight of seven days.
FIGURE 6A2-3 (e) —Ground-tracks of Kosmos 600, from right to left, of revs. 15, 63, 79, 47, 95, and 31 on October 17 through 22, 1973
Meanwhile, on October 20, Kosmos 692 had been launched from Plesetsk. It was a manoeuvrable type with a two-tone short-wave tracking beacon. This time the ground track was stabilized with hardly any lateral drift. Fig. 6A2-3 (f) shows that this occurred when
FIGURE 6A2-3(f) —Ground-tracks of Kosmos 602, from right to left, of revs. 15, 31, 47, 63, 79, 95, 111 and 127 on October 21 through 28, 1973.
The last four ground-tracks are practically coincident the ground-track ran directly through the area of the Suez Canal. Kosmos 602 was recovered after a nine-day flight on October 29. During the later stages of the flight it was following Kosmos 599 over the battle area after an interval of some 70 minutes.
These stages coincided with moves in the United Nations Security Council calling for an immediate cease-fire, and although Kosmos 603 (launched on October 27) flew over the battle area on October 28 and 29, no steps were taken to stabilize the ground-track until November 1 when perigee was lowered in the usual pre-war manner to 175 km. Subsequently, full stabilization was achieved by lowering the apogee on November 5 after 142 orbits. Fig. 6A2-3 (g) shows that this was when the ground-track, once again, passed through the southern end of the Suez Canal zone. It was recovered on November 9 after the13-day flight which was usual for "Morse code" satellites.
FIGUBE 6A2-3 (g) —Ground-tracks of Kosmos 603, from right to left, of revs. 110, 126, 15, 142, 158, 174, 190 and 31 on October 28 and 29 and November 3 through 8, 1973
The six-point peace agreement between Egypt and Israel was signed on November 11. Kosmos 607 had been launched on the previous day and, like its successors, Kosmos 609, 612, 616 and 625, was doubtless used to monitor the effectiveness of the cease-fire.
The importance of the role of these reconnaissance missions was emphasized in a series of articles which appeared in the London, Sunday Telegraph. (14) Under the sub-heading, "Cosmos knew better than Egypt," they wrote:
Kosygin asked about the Israeli "incursion" and Sadat explained that it was a stunt to enable Mrs. Meir to cheer up her compatriots. But by way of the Cosmos satellite and Intelligence reports the Soviets were getting quite a different picture. The embassy received information and Cosmos pictures which were shown to President Sadat, and the Soviet military attache spelled out for the Egyptians what it meant. Here were the Russians explaining in Cairo to the President of Egypt who did not know what was happening only a few miles away.
The first concrete measure to help was ordered at once, and before Kosygin returned to Moscow , the Antonovs began flying in 300 Soviet military personnel.
In the three examples cited above the targets of the reconnaissance were fairly obvious but, in most cases, it is more difficult to determine the prime target, even if one exists. In the absence of manoeuvres to produce a stabilized ground-track the only real clue is to be found in the location of the perigee of the orbit. This defines a band of latitude close to which the particular target lies. Greater confidence is obtained if it can be shown that the time of pass through perigee takes place around local noon. If the ground-track is subsequently stabilized the analyst is then presented with sixteen fairly precise locations spaced at approximately 22.5 ° intervals around the latitude of perigee. A glance at a terrestrial globe will show that some of these may be eliminated as they fall over the oceans or, in the northern hemisphere, within the territory of the "U.S.S.R.
The methodology can be outlined by consideration of a very recent flight with distinct peculiarities. Kosmos 759 was launched into a 62.8 ° inclination orbit from Plesetsk at around 0530 GMT on September 12, 1975. Although we had been expecting a launch following the recovery of Kosmos 757 on September 9, the launch took place 9.25 hours earlier than that of Kosmos 757 only sixteen days before. (15) Our mid-day monitoring session consequently failed to reveal the existence of the new satellite since it was no longer in range of the Soviet ground-stations at that time. We later learned that Wakelin picked up the two-tone short-wave beacon in Cyprus, at 0541 GMT shortly after insertion into orbit. Although TASS announced the launch at 1347 GMT it was not carried in the English news broadcasts from Radio Moscow that evening. I picked up strong two-tone signals on 19.994 MHz on my bed-side receiver at 0719 GMT on the Sunday morning at the start of the 35th orbit. This showed that it was a member of the special sub-set of non-manoeuvring payloads.
Aside from the unusual hour of launch, calculations based on two-line orbital elements issued by the Goddard Space Flight Center showed that the placing of perigee was also unusual in that, like that of Kosmos 720, it occurred close to 10 ° S on the southbound
pass. These two facts were shown to be interdependent when the time of passage through perigee was determined to be 1430 local Sun-time at the start of the mission, falling to 1100 on the day of recovery, for a given location. An inspection of an Atlas showed that only parts of South America, Africa, and northern Australia were situated at 10 ° S. However, on September 15, the London Daily Telegraph ran a piece on the withdrawal of the Royal Air Force from the Indian Ocean staging post of Gan in the Maldive Islands and referred to the U.S. Defense Department's proposed improvements to their base at Diego Garcia in the Chagos Archipelago. Here then w&s a potential target with the correct coordinates. Figure 6A2-4 shows the ground-tracks of Kosmos 759 across the area of the Indian Ocean. Whilst we cannot be sure that Diego Garcia was the prime target, since Angola and Timor also received a similar coverage, it will be seen that this satellite was well-positioned for photographic survey of Diego Garcia.both at the beginning and end of its flight.
Fig. 6A2-4. —Ground-tracks of Kosmos 759, from right to left, of revs. 2, 18, 145, 34, 161, 50, 177, 66, 82, 98, 114, 3 and 130 on September 12 through 23, 1975.
Goddard Space Flight Center also revealed that three other pieces, perhaps fairings and protective covers for instrumentation, in addition to the final rocket stage were jettisoned after a few hours of the mission, and that two further pieces were discarded on the day of recovery. Recovery was also unusual in that the recovery zone was in darkness at the time. Wakelin lost signals after nine minutes at 2021 GMT on September 23, pointing to a landing at around 2035.
This account of the Kosmos 759 mission not only illustrates the methodology but also emphasises the dangers of being too dogmatic when drawing conclusions. The flight duplicated the flight of Kosmos 720 in earlier-than-usual launch time, recovery in darkness, perigee height and location, radio signal-type, jettisoned pieces soon after launch and additional pieces (four in this case) on the day of recovery. It might well be that these two satellites had dual-purpose missions —military reconnaissance and Earth resources survey —and that the newspaper reference to Diego Garcia was purely coincidental and provided me with a convenient "red herring" . . . but then, that is all part of the fascination such a hobby provides!
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. Perry, G. E., J. D. Slater, J. Marshall and S. Grahn, Spaceflight. London, 8, 438, 1966
2. Perry, G. E., Flight International, London, 103, 811. May 24, 1973
3. Perry, G. E., and J. D. Slater, Flight International, London, 89, 842. November 12, 1964.
4. Perry, G. E., Spaceflight, London, Id, 204-206,1968.
5. Perry, G. B., Ibid.
6. Perry, G. E. and E. S. 'Flagg, Journal of the British Interplanetary Society, SS, 451-464, 1970.
7. 'Perry, G. E., Flight International, London, 9S, 844-845, May 22, 1969.
8. Perry, G. E. and S. Grahn, Spaceflight, London, 10, 431, 1968.
9. Perry, G. E. Spaceflight, London, IS, 69, 1974.
10. Perry, G. E. and g. Grahn, Spaceflight, London, 19, 142-143, 1968.
11. Perry, G. E. Flight International, London, 100, 31, July 1, 1971.
12. Perry, G. E., Spaceflight, London, It, 380, September 1972.
13. Perry, G. E. Flight International, London, 105, 240 and 245, February 21, 1974.
14. Dobson, C. and R. Payne, Why the Arabs didn't win, Sunday Telegraph, Lon [date?].
15. Recoveries normally take place In mid-week; In the last 18 months, almost two-thirds of the recoveries have been on Tuesday or Wednesdays. The Implication of this Is that, due to the standard 12 to 14-day durations of these missions, launches are made towards the end of the week. Aside from five Tuesday-launches, all launches of recoverable reconnaissance missions have been made on Wednesday (13), Thursday (7) and Friday (8).
* The late Mr. Perry was senior science master at the Kettering Grammar School, Kettering, England.
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