brody@eos.arc.nasa.gov (Adam R. Brody) (12/27/90)
A bunch of people requested my Soviet docking history so here it is, in 4 parts. Soviet Docking Experience Any discussion of spacecraft docking operations would be incomplete without mention of the accomplishments that the Soviets have had in this area. In 1990, the Soviets are inhabiting their eighth space station and as of July have had 35 successful autonomous dockings in space. (Friedman & Heinsheimer, 1990) Cosmonauts inhabit the Mir space station for many months at a time and unmanned vehicles automatically dock for resupply. Most of the information that follows was gleaned from the Almanac of Soviet Manned Space Flight, by Dennis Newkirk (1990). The Soviets began contemplating spacecraft docking operations when they realized they would require these techniques for racing the Americans to the moon. Their first plan was an Earth orbital rendezvous (EOR) leading to a lunar fly-by. They were to use the same A-2 boosters and launch facilities being developed for the Voskhod program and other unmanned missions. Each mission would involve five launches. Soyuz V tankers would automatically rendezvous and dock and then fuel the Soyuz B rocket waiting in Earth orbit. The manned Soyuz would dock with the fueled rocket then ultimately be launched around the moon. By 1964 they realized they were not developing the docking techniques fast enough to beat the Americans to the moon. They therefore decided to adopt a direct ascent profile, which involves launching directly from Earth to the moon, thereby eliminating the need for docking. After a series of failures, Zond 5B achieved the first lunar fly-by and return in September 1968. The spacecraft contained plants, turtles, flies, and worms. Some modifications were needed, however, as the returning capsule experien ced between ten and sixteen g's, far more than a human could endure. Zond 6 performed a similar mission in November but with g forces reduced by one-half. Technical difficulties delayed the December launch of Zond 7A (which most likely would have been manned) by one month allowing the US the first manned lunar fly-by with Apollo 8 in December. The rush to the moon hurt both the Soviets and the Americans deeply. In January 1967, during a launch pad rehearsal for Apollo 1, Virgil I. Grissom, Edward H. White, II, and Roger Chaffee died in a fire. Vladimir Komarov crashed to his death when the Soyuz 1 parachute shroud lines twisted in April 1967. These accidents delayed both the Apollo and Soyuz manned launches for over a year. "Apollo 1 and Soyuz 1 taught the world that victories in space would be neither easy nor cheap" (Aldrin & McConnel l, 1989, p. 172). In October 1967, two Soyuz vehicles, modified after the Soyuz 1 tragedy, tested and perfected automatic docking operations. Kosmos (Cosmos) 188 was launched three days after Kosmos 186 and completed a rendezvous on the first revolution. Kosmos 186 became the active vehicle and docked with Kosmos 188 which was cooperatively maintaining a stable attitude. Cosmos 186 was the first Soyuz to have maneuvered in orbit. This was the first automatic docking and the first to be achieved by unmanned vehicles. S ix months later, in April 1968, Cosmos 212 and Cosmos 213 repeated this procedure. Television cameras transmitted the undocking to ground control. These vehicles were essentially stripped down Soyuz spacecraft and the procedure they pioneered is similar to what is used today. A brief description follows. Radar contact between the two spacecraft is established in the capture phase. Both vehicles align themselves to a common axis. The chaser vehicle closes with a range rate of about 2 m/s at 350 m. This is about six times faster than suggested by NASA's "0.1 % rule" which limits approach velocity to no greater than 0.1% of the range per second (Sedej & Clarke, 1985; Oberg, 1988). The target vehicle such as a space station then uses attitude control rockets to maintain orientation in the mooring phase. The chaser craft extends a probe to effect a soft docking. "The extended probe prevents the airtight seals of the two spacecraft docking collars from being damaged if the initial contact is hard or off center" (Newkirk, 1990, p. 65). The vehicles complete soft docking when small latches on top of the probe catch the center of the drogue. "In the docking phase, the active ship reels its probe in and the ship's butt docking collars make an airtight connection" (Newkirk, 1990, p. 66). Latches in both collars hold the spacecraft together so electrical connections for communication and power may then be made. With Progress spacecraft, refueling connections also are consummated. Springs are used for disengaging. In October 1968, Colonel Georgiy Beregovoy attempted docking maneuvers in Soyuz 3. This was the first time the Soviets launched the passive target vehicle, Soyuz 2, first as the U.S. does. An automatic system guided Soyuz 3 from direct ascent to a range within 180 meters. Television cameras transmitted showed the approaching target to the Soviets. This flight was intended to accomplish the first Soviet manned docking but all docking attempts failed (Newkirk, 1990). In one instance, ground control dir ected a maneuver calculated from data transmitted by the rendezvous antennae on each vehicle (Baker, 1982).
brody@eos.arc.nasa.gov (Adam R. Brody) (12/27/90)
"Only 10 weeks after Soyuz 3, . . . the shortest gap between non-related manned space missions to that time," (Clark, 1988, p. 50) the Soviets launched Soyuz 4. "The launch of Soyuz 4 and Soyuz 5 in January 1969 marked the first winter launch in the Soviet manned space programme, suggesting that the flights had to be urgently completed" (Clark, p. 51). Another descendant of the lunar fly-by mission was the first manned docking in January 1969 with Soyuz 5. After practicing almost 800 dockings in the si mulator at Star City, Vladimir Shatalov accomplished an objective of the failed Soyuz 1 mission, i.e., the first Soviet manned docking. In Soyuz 4 he flew a manual approach to within a few kilometers of Soyuz 5. He then activated the automatic system which reduced the range to 100 meters. Shatalov then regained control and docked during a live Soviet television broadcast. This docking set a precedent in that it did not occur during the first orbit. The Soviets announced the combined spacecraft "as the world's "First Experimental Space Station" (Clark, p. 51). Yevgeniy Khrunov and Aleksey Yeliseyev used the opportunity to perform the first transfer from one spacecraft to another. The Soyuz was then modified for use as a space station ferry. Soyuz 10 and Soyuz 11 were the only flights with the original Salyut ferry. The most important change was the introduction of a crew transfer system which precluded the necessity to go EVA to board the station. The Soviets used Volga trainers to prepare for the docking operations. The Volga consisted of movable mockups of both Soyuz and Salyut mounted on rails. They would respond to commands made by the cosmonauts. A television view of the Salyut was presented to the Soyuz periscope system to give the crew a simulation of what an actual approach would be like (Clark, 1988). While manual control has been relegated to a back-up position for unmanned supply vehicles, the Soviets have utilized manual control for manned dockings to space stations. This began with Soyuz 10, in April 1971, which brought the first crew of Vladimir Shatalov, Aleksey Yeliseyev, and Nikolay Rukavishnikov to Salyut 1. Salyut 1, mankind's first space station, was launched in April 1971 aboard the Soviet Union's most powerful space launcher, the D-1, and re-entered the atmosphere in October. The Salyut assisted in the docking maneuver not only by maintaining attitude control, but "also made four orbit changes to match orbit with the approaching Soyuz" (Newkirk, 1990, p. 99). At a range of 180 meters, Shatalov took over control from the automatic system and performed a manual docking. Problems, most likely with the Soyuz, prevented the crew from boarding. The Soviets and the Americans both advocate manual back-up for automatic docking maneuvers. However the Soviets only resort to the manual system upon failure of the automatic one, while the Americans tend to use manual control whenever it is available, not just as a back-up control mode. Such is the case with shuttle (and other advanced aircraft) landings where the mere existence of a manual control capability is cited as a justification for using pilot control instead of the automated system. In an October 1970 meeting in Moscow, the Americans and the Soviets started formulating plans for the Apollo-Soyuz Test Project (ASTP). During a June 1971 meeting in Houston, "[Boris ] Petrov expressed the preference of the Soviet Academy of Sciences for a joint docking flight employing the androgynous docking system" (Baker, 1982, p. 408). This could be accomplished either with a Soyuz docking with a Skylab/Apollo or an Apollo docking with a Salyut/Soyuz. The latter was established as the baseline miss ion. In June 1971, Soyuz 11 was the next (and last) vehicle to dock with Salyut 1. The automated system reduced the range from 6 km to 100 meters. Georgi Dobrovolsky then took over control at a range of 100 meters and a velocity of 0.9 m/s. (This is nine times faster than suggested by the 0.1 % rule.) By 60 meters, he reduced the range rate to 0.3 m/s. Dobrovolsky then completed the docking maneuver. The crew became the first to inhabit the first space station. After a record 24-day mission, the mission ended in disaster as the air escaped through an open valve 11 minutes before the craft re-entered the atmosphere. Twelve pyrotechnic devices, used for separation, fired simultaneously rather than sequentially, releasing a seal on the spacecraft's pressure equalization valve. The atmosphere escaped in approximately 30 seconds while the cosmonauts were in the middle of a 60 second procedure to close the valve manually. Shatalov consequently replaced General Nikolai Kamanin as head of the cosmonaut corp. A redesign of the station was necessary but since this would take longer than the Salyut's lifetime to complete, the station was deorbited. More than two years passed before the next manned mission.
brody@eos.arc.nasa.gov (Adam R. Brody) (12/27/90)
The Soyuz Ferry was created to bring crews to Salyut space stations. It contained an automatic rendezvous and docking system known as Igla ("needle"). As in earlier Soyuz docking missions, both spacecraft maneuvered actively. The Soyuz Ferry had its first manned flight, Soyuz 12, in September 1973. Since both Salyut 1 and Salyut 2 failed in the previous year, this flight had to simulate transport to a space station. (Salyut 2 most likely had an attitude control thruster stuck on and broke up in orbit
before it was manned.)
Soyuz 13, launched in December 1973, was an independent mission and did not dock with a station. Soyuz 14 was the first operational use of the ferry and took the only Salyut 3 crew to orbit in July 1974. Automated rendezvous was used to reduce the range from 1000 meters to within 100 meters. Pavel Popovich then performed manual docking.
This procedure of manual control takeover at approximately 100 meters continued with Alesksei Gubarev on Soyuz 17, January 1975. Pyotr Klimuk performed similarly in May 1975 with Soyuz 18B.
Soyuz 19, better know as the Apollo-Soyuz Test Project, "was the first Soviet manned launch ever whose time was announced in advance and was the first to be televised live" (Newkirk, 1990, p. 140). Apollo was the active vehicle because of its greater fuel supply. The Soyuz merely had to maintain a fixed attitude toward the approaching Apollo and match roll rates.
Soyuz 20 tested the Progress automated unmanned cargo transport systems in November 1975. Progress 1, however, did not fly until January 1978. Based on the Soyuz, the Progress carried twice as much rendezvous and docking instrumentation as the Soyuz Ferry. Also, a second video camera was mounted on the outside to give ground controllers a stereo view of the automatic docking. "Simultaneous transmissions of telemetry from Progress to Salyut and the ground enabled both the control center and the cosmona
uts to assist with docking if necessary" (Baker, 1982, p. 524).
Progress 1 took two days approaching Salyut 6 as Soyuz 20 had done approaching Salyut 4. Manned spacecraft typically perform the approach in one day. "Since the Progress was unmanned, the crew did not retreat to the Soyuz during the docking as when the Soyuz 27 docked, they instead manned the station's controls ready to maneuver away from the approaching Progress in case of a malfunction" (Newkirk, 1990, p. 179). Since the Progress was expendable, plume impingement upon it caused by an emergency Salyut
separation maneuver was not a concern. None of the Progress missions through May 1988 had any docking problems although there were occasional problems with manned missions.
The Soyuz-T then replaced the Soyuz Ferry. It "included a new computer system and was claimed to be more automated than the earlier Soyuz variants; however, in flight the cosmonauts often had to take over manual control when the automatic systems apparently malfunctioned during docking manoeuvres" (Clark, 1988, p. 98). Soyuz T-1 flew in an unmanned configuration in December 1979.
In June 1980, the Argon docking computer flew its maiden launch on the first manned Soyuz T flight, Soyuz T-2. Argon selects which of several possible approaches to fly to a space station and then flies it with manual override capability. It similarly controls descent. Its operation required that the crew study computer programming. This training may have saved the mission as the automated docking system failed at a range of 180 meters from Salyut 6. "This was a problem which would be regularly repea
ted during Soyuz-T missions" (Clark, 1988, p. 120). Yuri Malyshev, a rookie, took over control and completed a successful manual docking. Aleksey Yeliseyev explained that the crew and flight controllers had not practiced the approach the computer selected so the crew decided to take over control to be better prepared in the event of an emergency. The crew claimed the automated system would have been successful if given the opportunity (Newkirk, 1990).
Soyuz 38, the seventh international crew, was launched in September 1980 with the first black cosmonaut. The automated system controlled not only the rendezvous but also the docking. The next manned flight, Soyuz T-3, was launched in November 1980. Its Argon automatic docking system performed the docking maneuver from a range of 5 km.
The Soviets' Mir "Peace" space station evolved from earlier Salyut designs and was launched in February 1986. The station contains five docking drogues with a manipulator system which moves incoming modules from the forward port where they have docked to a side port. The Kurs "course" docking system was incorporated into the forward port, which eliminated the need for attitude control by the station during the docking maneuver (Newkirk, 1990). Clark (1988) claims the rear port also was outfitted with t
he Kurs system in addition to the old Igla system which would accommodate Progress freighters.
Mir's first crew was launched March 1986 on Soyuz T-15 with live Soviet television coverage. The Igla system controlled the approach to within 200 meters of Mir's aft docking port which was compatible with Soyuz T and Progress. Leonid Kizim then flew around to the forward port which was instrumented with the new Kurs system to be used with Soyuz TM and Star modules. The Soyuz was incapable of automatic docking at the forward port but the laser range finder that was first used on the Soyuz T-13 flight in
June 1985 aided Kizim. Kizim completed a manual docking from an initial range of 60 meters. In May, the crew performed the first station-to-station transfer by flying over to
Salyut 7 to reactivate it. Once again, the hand-held laser range finder was used to generate range data. The automatic system was used from 5 km until Kizim took over manual control and docked. The crew returned to Mir at the end of June. After the crew used the Igla rendezvous system to reduce the range from 200 meters, Kizim took over control at a range of 50 meters from the rear docking port and maneuvered to dock at the forward port.
The Kurs rendezvous system was demonstrated in May 1986 with an unmanned Soyuz TM-1. This system does not require target vehicle transponders and can dock with a station at any relative attitude. It "makes contact with the station at a range of 200 km and docking lock-on begins at 20 to 30 km distance" (Newkirk, 1990, p. 313). Kurs presents closing rate data from the docking radar to the cosmonauts.
On March 31, 1987, the Kvant module, the first to be sent to Mir, was launched 10 out of plane with Mir in an approach similar to that of Star modules. During its approach to Mir on April 5, the cosmonauts were suited up "in the Soyuz TM in case of a collision. The spacecraft started its approach at 17 km distance using the old Igla docking system. At 500 meters distance, the Kvant's forward docking camera was activated and the docking probe extended. When Kvant was only 200 meters from the station an
d preparing for final
docking maneuvers, Flight Director Ryumin radioed to the cosmonauts that Kvant had lost its lock-on to Mir's docking transponders. . . . [Kvant drifted slightly and] was rotating slightly as it passed within 10 meters of Mir" (Newkirk, 1990, pp. 321-322). "The Kvant thrusters failed to slow down the module and it flew past Mir" (Clark, 1988, p. 155). Mission controllers spent several days analyzing the problem during which time the Kvant drifted to a range of 400 km. Ground controllers brought Kvant bac
k in the vicinity of Mir. The Igla automatic docking system was activated at a range of 22 km. Lock-on to Mir's docking transponder signal was achieved and at a range of 1000 meters, the approach velocity was 2.5 meters per second. (This is 2.5 times the rate suggested by NASA's 0.1% rule.) The relative velocity was decreased to .32 meters per second at 26 meters (12.3 times the 0.1% rule rate of .026 meters per second). Soft docking was achieved within 21 minutes of Igla lock-on.
During the docking of Progress 33 in November 1987, the Soviets experimented with new station orienting procedures since the Igla system, used by the Progress, required active maneuvering by the target vehicle. Typical fuel expenditures for docking a Progress to Mir were approximately 192 kg using the old system. "The new Igla procedure reduced this amount to about 82 kg" (Newkirk, 1990, p. 322).
The first launch of the Progress M, a modified Progress, occurred in August 1989. It has an increased on-orbit stay time, "has an improved automated docking system and also is able to transfer unused fuel to the space station" (Rains, 1990b, p. 8). The Progress M also possesses a return capsule which was successfully tested on mission Progress M5, in November 1990 (Kiernan, 1990)..
Docking Failures
Despite their great experience with docking both manned and unmanned spacecraft, the Soviets have had several failures during docking maneuvers. Failures occurred with Soyuz 15 in August 1974, Soyuz 23 in October 1976, Soyuz 25 in October 1977, Soyuz 33 in April 1979, and Soyuz T-8 in April 1983.
The failure of Soyuz 15 to dock with Salyut 3 was due either to a repeated system failure at the time to initiate the manual control phase at a range of 100 meters (Clark, 1988), or, "the automatic system malfunctioned twice, pushing the ship out of control with excessive engine burns while only 30 to 50 meters from the station" (Newkirk, 1990, p. 128). With a limited battery and fuel supply, the vehicle had to de-orbit when the docking failed.
In October 1976, Souyz 23 was aborted because of a malfunction in the automatic docking system. This occurred before the range of the Soyuz to the Salyut 5 station was reduced to 100 meters. Since the crew of Vyacheslav Zudov and Veleri Rozhdestvenski were trained to take over from 100 meters, but not before, the crew were forced to land as soon as possible. The manual back-up mode was not extensive enough to save this
mission. As Tass reported, "the spaceship Soyuz 23 was put into the automatic regime for the approach to Salyut 5. Docking with the Salyut 5 station was cancelled because of an unplanned operation of the approach control system of the ship" (Clark, 1988, p. 74).brody@eos.arc.nasa.gov (Adam R. Brody) (12/27/90)
Viktor Grobatko flew a successful docking of Soyuz 24 in February 1977 after taking over control at a range of 80 meters. The Soviets' success was short-lived, however, as failure plagued Soyuz 25 in October that year. Vladimir Kovalyonok began the docking maneuver from 120 meters but five docking attempts to the Salyut 6 station failed due to a faulty docking fixture on the Soyuz. As the news release stated, "At 07.09 Moscow time today [10 October] the automatic rendezvous of the Soyuz 25 ship and the Salyut 6 station was begun. From a distance of 120 metres, the vehicles performed a docking manoeuvre. Due to deviations from the planned procedure for docking, the link-up was called off. The crew has begun making preparations for a return to Earth" (Clark, 1988, pp. 104-5). While soft docking was achieved, hard docking enabling electrical connections to be made was not. This failure resulted in the prohibition of all-rookie crews and Romanenko and Ivanchenkov from the all-rookie back-up crew were each paired with veteran cosmonauts. Another failure occurred in April 1983 with the aborted Soyuz T-8 mission. Although the launch shroud accidentally removed the rendezvous radar antenna, mission controllers decided to violate their own rules and let Vladimir Titov attempt an optical rendezvous from 10 km. This had never been done before by the Soviets and was particularly risky since Titov later claimed he had not previously trained for manual approach and docking. Flight directors assisted Titov by computing the range rate after Titov reported Salyut size estimates. After a range of 330 meters was passed, the Soyuz slipped out of contact with the ground. Without his range rate source, Titov was not sure of his closing rate. Although he was able to reduce his range to 75 meters with the aid of the Soyuz's floodlight, he approached at too high a velocity and fearing a collision, fired thrusters to change orbits and abort the docking (Newkirk, 1990). "There had been ten manned launches to Salyut 1, Salyut 3, Salyut 4 and Salyut 5. Of these one had failed to reach orbit (Soyuz 18-1), two had failed to dock with their Salyuts (Soyuz 15, Soyuz 23), one had docked but the crew had been unable to transfer to their Salyut (Soyuz 10) and one crew had perished during their return to Earth (Soyuz 11). This left the Soviets with a 50 per cent success rate, if we deem Soyuz 21 as a successful mission even though it was terminated earlier than planned. . . . During 1977-1981 there were 16 Soyuz spacecraft launched towards Salyut 6 and of these only one failed to dock (Soyuz 33) and one docked but the crew could not transfer (Soyuz 25); additionally, there were 4 launches of Soyuz-T craft, 12 launches of Progress craft and the Cosmos 1267 mission P all of which successfully docked with Salyut 6. For Salyut 6 the success rate was 94 per cent" (Clark, 1988, pp. 126-7). Docking Recoveries Not all failures resulted in the loss of the mission. During the Soyuz T-6 mission in June 1982, Vladimir Dzhanibekov rescued the docking with a manual maneuver after the automatic system failed. After turning the spacecraft around to perform the braking maneuver, at 900 meters from Salyut 7, the Argon computer failed and would not realign with the station. Dzhanibekov disconnected the computer and maneuvered the Soyuz along all three axes to resume pointing at the station. His successful docking from such a far range under manual control was a major achievement (Newkirk, 1990). The regular failure of the Soyuz-T system during final approach was usually followed by manual recovery and presumably led to computer improvements in Soyuz-TM (Clark, 1988). Vladimir Dzhanibekov was no stranger to docking operations as this was his third. After five flights (he is the first, and as of 1986 still the only, cosmonaut to fly more than three missions), he is the Soviet Union's most experienced cosmonaut. Dzhanibekov served as back-up commander to Alexei Leonov for ASTP but did not fly until January 1978 with Soyuz 27 when he achieved the first double docking with a manned space station. In March 1981 he flew his second flight in Soyuz 39 with Jugerdemidiin Gurragcha. In July 1984, on Soyuz T-12, he accompanied Svetlana Savitskaya in the first extra-vehicular activity (EVA) by a female (Hillyer, 1986). As prime commander of the Soyuz T-13 mission, Dzhanibekov had the privilege of testing a new manual docking system in June 1985. The primary purpose of this flight was to rescue Salyut-7 after it had lost all power and was rolling aimlessly in space. As Dzhanibekov says, "There were great difficulties with preparation for docking with this object. The station seemed to us as a dead space object and nothing more. And specialists were afraid that it would rotate in space at too high a speed in three axes. So we had to train and to find out this optimum way to maneuver around the station to find the best light conditions of the Sun. And of course to train our hand . . . everything had to be done manually" (Hillyer, 1986, p. 17). Equipped with a laser rangefinder, Dzhanibekov compared the measured range to Salyut-7 with the range computed by his spacecraft. At 10 km, Dzhanibekov interrupted the automated approach to input Salyut 7 attitude data into the Soyuz docking computer. The automatic approach resumed until "3 km distance, at a rate of 12, and later 6 meters/second when Dzhanibekov took control" (Newkirk, 1990, p. 270). At three km, "there started to be a difference between our measurements and the radar-calculated data. So I had to take the handles and step in to direct manually" (Hillyer, 1986, p. 17). "At 2 km, the crew used a new optical guidance system, hand-held laser range finder and a night vision instrument, to see and measure distance to the station" (Newkirk, p. 270). At a range of 200 meters, Dzhanibekov nulled the approach velocity because the sun was behind the station making visibility poor. For 10 minutes he circled the station on damage patrol. Then, in a roll-matching maneuver, he docked with the station. "(Later Dzhanibekov would say, TDocking is like driving a seven-ton truck with fragile freight on an icy road into a narrow gate at the end of this road')" (Kramer, 1990, p. 57). The docking was successful and Dzhanibekov has similar opinions about manual control as Buzz Aldrin. He shares Aldrin's skepticism about automated systems and claims that manual control gives the ability to "operate in wider range" (Hillyer, p. 18). Admittedly, one of the main reasons for manual control is emotional or political, namely, pilots would rather fly than watch. However, the successful rescues mentioned previously would not have been possible without human intervention. Another recovery was made with Soyuz TM-5 (the thirteenth international crew-Bulgaria), in June 1988. Although the Kurs system malfunctioned during the final approach, flight controllers diagnosed the problem and a successful docking was completed within two days of the launch. In June 1990, a docking recovery was achieved with an unmanned vehicle. Docking of the Kristal module with the Mir space station was automatically aborted when a Kristal computer discovered a malfunction in one of its attitude control thrusters. Ground controllers used a backup set of thrusters to complete the docking operation successfully (Rains, 1990a).
brody@eos.arc.nasa.gov (Adam R. Brody) (12/27/90)
As most of you have noticed, I have been having an awful lot of trouble
with this. Keep your fingers crossed!!
Soviet Docking Experience
Any discussion of spacecraft docking operations
would be incomplete without mention of the
accomplishments that the Soviets have had in this area. In
1990, the Soviets are inhabiting their eighth space station
and as of July have had 35 successful autonomous dockings
in space. (Friedman & Heinsheimer, 1990) Cosmonauts
inhabit the Mir space station for many months at a time and
unmanned vehicles automatically dock for resupply. Most
of the information that follows was gleaned from the
Almanac of Soviet Manned Space Flight, by Dennis
Newkirk (1990).
The Soviets began contemplating spacecraft docking
operations when they realized they would require these
techniques for racing the Americans to the moon. Their first
plan was an Earth orbital rendezvous (EOR) leading to a
lunar fly-by. They were to use the same A-2 boosters and
launch facilities being developed for the Voskhod program
and other unmanned missions. Each mission would involve
five launches. Soyuz V tankers would automatically
rendezvous and dock and then fuel the Soyuz B rocket
waiting in Earth orbit. The manned Soyuz would dock with
the fueled rocket then ultimately be launched around the
moon.
By 1964 they realized they were not developing the
docking techniques fast enough to beat the Americans to the
moon. They therefore decided to adopt a direct ascent
profile, which involves launching directly from Earth to the
moon, thereby eliminating the need for docking. After a
series of failures, Zond 5B achieved the first lunar fly-by
and return in September 1968. The spacecraft contained
plants, turtles, flies, and worms. Some modifications were
needed, however, as the returning capsule experienced
between ten and sixteen g's, far more than a human could
endure. Zond 6 performed a similar mission in November
but with g forces reduced by one-half. Technical difficulties
delayed the December launch of Zond 7A (which most likely
would have been manned) by one month allowing the US
the first manned lunar fly-by with Apollo 8 in December.
The rush to the moon hurt both the Soviets and the
Americans deeply. In January 1967, during a launch pad
rehearsal for Apollo 1, Virgil I. Grissom, Edward H. White,
II, and Roger Chaffee died in a fire. Vladimir Komarov
crashed to his death when the Soyuz 1 parachute shroud
lines twisted in April 1967. These accidents delayed both
the Apollo and Soyuz manned launches for over a year.
"Apollo 1 and Soyuz 1 taught the world that victories in
space would be neither easy nor cheap" (Aldrin &
McConnell, 1989, p. 172).
In October 1967, two Soyuz vehicles, modified after
the Soyuz 1 tragedy, tested and perfected automatic docking
operations. Kosmos (Cosmos) 188 was launched three days
after Kosmos 186 and completed a rendezvous on the first
revolution. Kosmos 186 became the active vehicle and
docked with Kosmos 188 which was cooperatively
maintaining a stable attitude. Cosmos 186 was the first
Soyuz to have maneuvered in orbit. This was the first
automatic docking and the first to be achieved by unmanned
vehicles. Six months later, in April 1968, Cosmos 212 and
Cosmos 213 repeated this procedure. Television cameras
transmitted the undocking to ground control. These vehicles
were essentially stripped down Soyuz spacecraft and the
procedure they pioneered is similar to what is used today. A
brief description follows.
Radar contact between the two spacecraft is
established in the capture phase. Both vehicles align
themselves to a common axis. The chaser vehicle closes
with a range rate of about 2 m/s at 350 m. This is about six
times faster than suggested by NASA's "0.1 % rule" which
limits approach velocity to no greater than 0.1% of the range
per second (Sedej & Clarke, 1985; Oberg, 1988).
The target vehicle such as a space station then uses
attitude control rockets to maintain orientation in the mooring
phase. The chaser craft extends a probe to effect a soft
docking. "The extended probe prevents the airtight seals of
the two spacecraft docking collars from being damaged if the
initial contact is hard or off center" (Newkirk, 1990, p. 65).
The vehicles complete soft docking when small latches on
top of the probe catch the center of the drogue.
"In the docking phase, the active ship reels its probe
in and the ship's butt docking collars make an airtight
connection" (Newkirk, 1990, p. 66). Latches in both collars
hold the spacecraft together so electrical connections for
communication and power may then be made. With
Progress spacecraft, refueling connections also are
consummated. Springs are used for disengaging.
In October 1968, Colonel Georgiy Beregovoy
attempted docking maneuvers in Soyuz 3. This was the first
time the Soviets launched the passive target vehicle, Soyuz
2, first as the U.S. does. An automatic system guided
Soyuz 3 from direct ascent to a range within 180 meters.
Television cameras transmitted showed the approaching
target to the Soviets. This flight was intended to accomplish
the first Soviet manned docking but all docking attempts
failed (Newkirk, 1990). In one instance, ground control
directed a maneuver calculated from data transmitted by the
rendezvous antennae on each vehicle (Baker, 1982).
"Only 10 weeks after Soyuz 3, . . . the shortest gap
between non-related manned space missions to that time,"
(Clark, 1988, p. 50) the Soviets launched Soyuz 4. "The
launch of Soyuz 4 and Soyuz 5 in January 1969 marked the
first winter launch in the Soviet manned space programme,
suggesting that the flights had to be urgently completed"
(Clark, p. 51). Another descendant of the lunar fly-by
mission was the first manned docking in January 1969 with
Soyuz 5. After practicing almost 800 dockings in the
simulator at Star City, Vladimir Shatalov accomplished an
objective of the failed Soyuz 1 mission, i.e., the first Soviet
manned docking. In Soyuz 4 he flew a manual approach to
within a few kilometers of Soyuz 5. He then activated the
automatic system which reduced the range to 100 meters.
Shatalov then regained control and docked during a live
Soviet television broadcast. This docking set a precedent in
that it did not occur during the first orbit. The Soviets
announced the combined spacecraft "as the world's "First
Experimental Space Station" (Clark, p. 51). Yevgeniy
Khrunov and Aleksey Yeliseyev used the opportunity to
perform the first transfer from one spacecraft to another.
The Soyuz was then modified for use as a space
station ferry. Soyuz 10 and Soyuz 11 were the only flights
with the original Salyut ferry. The most important change
was the introduction of a crew transfer system which
precluded the necessity to go EVA to board the station.
The Soviets used Volga trainers to prepare for the
docking operations. The Volga consisted of movable
mockups of both Soyuz and Salyut mounted on rails. They
would respond to commands made by the cosmonauts. A
television view of the Salyut was presented to the Soyuz
periscope system to give the crew a simulation of what an
actual approach would be like (Clark, 1988).
While manual control has been relegated to a back-up
position for unmanned supply vehicles, the Soviets have
utilized manual control for manned dockings to space
stations. This began with Soyuz 10, in April 1971, which
brought the first crew of Vladimir Shatalov, Aleksey
Yeliseyev, and Nikolay Rukavishnikov to Salyut 1. Salyut
1, mankind's first space station, was launched in April 1971
aboard the Soviet Union's most powerful space launcher,
the D-1, and re-entered the atmosphere in October. The
Salyut assisted in the docking maneuver not only by
maintaining attitude control, but "also made four orbit
changes to match orbit with the approaching Soyuz"
(Newkirk, 1990, p. 99). At a range of 180 meters, Shatalov
took over control from the automatic system and performed a
manual docking. Problems, most likely with the Soyuz,
prevented the crew from boarding.
The Soviets and the Americans both advocate manual
back-up for automatic docking maneuvers. However the
Soviets only resort to the manual system upon failure of the
automatic one, while the Americans tend to use manual
control whenever it is available, not just as a back-up control
mode. Such is the case with shuttle (and other advanced
aircraft) landings where the mere existence of a manual
control capability is cited as a justification for using pilot
control instead of the automated system.
In an October 1970 meeting in Moscow, the
Americans and the Soviets started formulating plans for the
Apollo-Soyuz Test Project (ASTP). During a June 1971
meeting in Houston, "[Boris ] Petrov expressed the
preference of the Soviet Academy of Sciences for a joint
docking flight employing the androgynous docking system"
(Baker, 1982, p. 408). This could be accomplished either
with a Soyuz docking with a Skylab/Apollo or an Apollo
docking with a Salyut/Soyuz. The latter was established as
the baseline mission.
In June 1971, Soyuz 11 was the next (and last)
vehicle to dock with Salyut 1. The automated system
reduced the range from 6 km to 100 meters. Georgi
Dobrovolsky then took over control at a range of 100 meters
and a velocity of 0.9 m/s. (This is nine times faster than
suggested by the 0.1 % rule.) By 60 meters, he reduced the
range rate to 0.3 m/s. Dobrovolsky then completed the
docking maneuver. The crew became the first to inhabit the
first space station. After a record 24-day mission, the
mission ended in disaster as the air escaped through an open
valve 11 minutes before the craft re-entered the atmosphere.
Twelve pyrotechnic devices, used for separation, fired
simultaneously rather than sequentially, releasing a seal on
the spacecraft's pressure equalization valve. The atmosphere
escaped in approximately 30 seconds while the cosmonauts
were in the middle of a 60 second procedure to close the
valve manually.
Shatalov consequently replaced General Nikolai
Kamanin as head of the cosmonaut corp. A redesign of the
station was necessary but since this would take longer than
the Salyut's lifetime to complete, the station was deorbited.
More than two years passed before the next manned
mission.
The Soyuz Ferry was created to bring crews to
Salyut space stations. It contained an automatic rendezvous
and docking system known as Igla ("needle"). As in earlier
Soyuz docking missions, both spacecraft maneuvered
actively. The Soyuz Ferry had its first manned flight, Soyuz
12, in September 1973. Since both Salyut 1 and Salyut 2
failed in the previous year, this flight had to simulate
transport to a space station. (Salyut 2 most likely had an
attitude control thruster stuck on and broke up in orbit before
it was manned.)
Soyuz 13, launched in December 1973, was an
independent mission and did not dock with a station. Soyuz
14 was the first operational use of the ferry and took the only
Salyut 3 crew to orbit in July 1974. Automated rendezvous
was used to reduce the range from 1000 meters to within
100 meters. Pavel Popovich then performed manual
docking.
This procedure of manual control takeover at
approximately 100 meters continued with Alesksei Gubarev
on Soyuz 17, January 1975. Pyotr Klimuk performed
similarly in May 1975 with Soyuz 18B.
Soyuz 19, better know as the Apollo-Soyuz Test
Project, "was the first Soviet manned launch ever whose
time was announced in advance and was the first to be
televised live" (Newkirk, 1990, p. 140). Apollo was the
active vehicle because of its greater fuel supply. The Soyuz
merely had to maintain a fixed attitude toward the
approaching Apollo and match roll rates.
Soyuz 20 tested the Progress automated unmanned
cargo transport systems in November 1975. Progress 1,
however, did not fly until January 1978. Based on the
Soyuz, the Progress carried twice as much rendezvous and
docking instrumentation as the Soyuz Ferry. Also, a second
video camera was mounted on the outside to give ground
controllers a stereo view of the automatic docking.
"Simultaneous transmissions of telemetry from Progress to
Salyut and the ground enabled both the control center and the
cosmonauts to assist with docking if necessary" (Baker,
1982, p. 524).
Progress 1 took two days approaching Salyut 6 as
Soyuz 20 had done approaching Salyut 4. Manned
spacecraft typically perform the approach in one day. "Since
the Progress was unmanned, the crew did not retreat to the
Soyuz during the docking as when the Soyuz 27 docked,
they instead manned the station's controls ready to maneuver
away from the approaching Progress in case of a
malfunction" (Newkirk, 1990, p. 179). Since the Progress
was expendable, plume impingement upon it caused by an
emergency Salyut separation maneuver was not a concern.
None of the Progress missions through May 1988 had any
docking problems although there were occasional problems
with manned missions.
The Soyuz-T then replaced the Soyuz Ferry. It
"included a new computer system and was claimed to be
more automated than the earlier Soyuz variants; however, in
flight the cosmonauts often had to take over manual control
when the automatic systems apparently malfunctioned during
docking manoeuvres" (Clark, 1988, p. 98). Soyuz T-1 flew
in an unmanned configuration in December 1979.
In June 1980, the Argon docking computer flew its
maiden launch on the first manned Soyuz T flight, Soyuz T-
2. Argon selects which of several possible approaches to fly
to a space station and then flies it with manual override
capability. It similarly controls descent. Its operation
required that the crew study computer programming. This
training may have saved the mission as the automated
docking system failed at a range of 180 meters from Salyut
6. "This was a problem which would be regularly repeated
during Soyuz-T missions" (Clark, 1988, p. 120). Yuri
Malyshev, a rookie, took over control and completed a
successful manual docking. Aleksey Yeliseyev explained
that the crew and flight controllers had not practiced the
approach the computer selected so the crew decided to take
over control to be better prepared in the event of an
emergency. The crew claimed the automated system would
have been successful if given the opportunity (Newkirk,
1990).
Soyuz 38, the seventh international crew, was
launched in September 1980 with the first black cosmonaut.
The automated system controlled not only the rendezvous
but also the docking. The next manned flight, Soyuz T-3,
was launched in November 1980. Its Argon automatic
docking system performed the docking maneuver from a
range of 5 km.
The Soviets' Mir "Peace" space station evolved from
earlier Salyut designs and was launched in February 1986.
The station contains five docking drogues with a manipulator
system which moves incoming modules from the forward
port where they have docked to a side port. The Kurs
"course" docking system was incorporated into the forward
port, which eliminated the need for attitude control by the
station during the docking maneuver (Newkirk, 1990).
Clark (1988) claims the rear port also was outfitted with the
Kurs system in addition to the old Igla system which would
accommodate Progress freighters.
Mir's first crew was launched March 1986 on Soyuz
T-15 with live Soviet television coverage. The Igla system
controlled the approach to within 200 meters of Mir's aft
docking port which was compatible with Soyuz T and
Progress. Leonid Kizim then flew around to the forward
port which was instrumented with the new Kurs system to
be used with Soyuz TM and Star modules. The Soyuz was
incapable of automatic docking at the forward port but the
laser range finder that was first used on the Soyuz T-13
flight in June 1985 aided Kizim. Kizim completed a manual
docking from an initial range of 60 meters. In May, the
crew performed the first station-to-station transfer by flying
over to Salyut 7 to reactivate it. Once again, the hand-held
laser range finder was used to generate range data. The
automatic system was used from 5 km until Kizim took over
manual control and docked. The crew returned to Mir at the
end of June. After the crew used the Igla rendezvous system
to reduce the range from 200 meters, Kizim took over
control at a range of 50 meters from the rear docking port
and maneuvered to dock at the forward port.
The Kurs rendezvous system was demonstrated in
May 1986 with an unmanned Soyuz TM-1. This system
does not require target vehicle transponders and can dock
with a station at any relative attitude. It "makes contact with
the station at a range of 200 km and docking lock-on begins
at 20 to 30 km distance" (Newkirk, 1990, p. 313). Kurs
presents closing rate data from the docking radar to the
cosmonauts.
On March 31, 1987, the Kvant module, the first to
be sent to Mir, was launched 10 out of plane with Mir in an
approach similar to that of Star modules. During its
approach to Mir on April 5, the cosmonauts were suited up
"in the Soyuz TM in case of a collision. The spacecraft
started its approach at 17 km distance using the old Igla
docking system. At 500 meters distance, the Kvant's
forward docking camera was activated and the docking
probe extended. When Kvant was only 200 meters from the
station and preparing for final docking maneuvers, Flight
Director Ryumin radioed to the cosmonauts that Kvant had
lost its lock-on to Mir's docking transponders. . . . [Kvant
drifted slightly and] was rotating slightly as it passed within
10 meters of Mir" (Newkirk, 1990, pp. 321-322). "The
Kvant thrusters failed to slow down the module and it flew
past Mir" (Clark, 1988, p. 155). Mission controllers spent
several days analyzing the problem during which time the
Kvant drifted to a range of 400 km. Ground controllers
brought Kvant back in the vicinity of Mir. The Igla
automatic docking system was activated at a range of 22 km.
Lock-on to Mir's docking transponder signal was achieved
and at a range of 1000 meters, the approach velocity was 2.5
meters per second. (This is 2.5 times the rate suggested by
NASA's 0.1% rule.) The relative velocity was decreased to
.32 meters per second at 26 meters (12.3 times the 0.1% rule
rate of .026 meters per second). Soft docking was achieved
within 21 minutes of Igla lock-on.
During the docking of Progress 33 in November
1987, the Soviets experimented with new station orienting
procedures since the Igla system, used by the Progress,
required active maneuvering by the target vehicle. Typical
fuel expenditures for docking a Progress to Mir were
approximately 192 kg using the old system. "The new Igla
procedure reduced this amount to about 82 kg" (Newkirk,
1990, p. 322).
The first launch of the Progress M, a modified
Progress, occurred in August 1989. It has an increased on-
orbit stay time, "has an improved automated docking system
and also is able to transfer unused fuel to the space station"
(Rains, 1990b, p. 8). The Progress M also possesses a
return capsule which was successfully tested on mission
Progress M5, in November 1990 (Kiernan, 1990)..
Docking Failures
Despite their great experience with docking both
manned and unmanned spacecraft, the Soviets have had
several failures during docking maneuvers. Failures
occurred with Soyuz 15 in August 1974, Soyuz 23 in
October 1976, Soyuz 25 in October 1977, Soyuz 33 in April
1979, and Soyuz T-8 in April 1983.
The failure of Soyuz 15 to dock with Salyut 3 was
due either to a repeated system failure at the time to initiate
the manual control phase at a range of 100 meters (Clark,
1988), or, "the automatic system malfunctioned twice,
pushing the ship out of control with excessive engine burns
while only 30 to 50 meters from the station" (Newkirk,
1990, p. 128). With a limited battery and fuel supply, the
vehicle had to de-orbit when the docking failed.
In October 1976, Souyz 23 was aborted because of a
malfunction in the automatic docking system. This occurred
before the range of the Soyuz to the Salyut 5 station was
reduced to 100 meters. Since the crew of Vyacheslav Zudov
and Veleri Rozhdestvenski were trained to take over from
100 meters, but not before, the crew were forced to land as
soon as possible. The manual back-up mode was not
extensive enough to save this mission. As Tass reported,
"the spaceship Soyuz 23 was put into the automatic regime
for the approach to Salyut 5. Docking with the Salyut 5
station was cancelled because of an unplanned operation of
the approach control system of the ship" (Clark, 1988, p.
74).
Viktor Grobatko flew a successful docking of Soyuz
24 in February 1977 after taking over control at a range of
80 meters. The Soviets' success was short-lived, however,
as failure plagued Soyuz 25 in October that year. Vladimir
Kovalyonok began the docking maneuver from 120 meters
but five docking attempts to the Salyut 6 station failed due to
a faulty docking fixture on the Soyuz. As the news release
stated, "At 07.09 Moscow time today [10 October] the
automatic rendezvous of the Soyuz 25 ship and the Salyut 6
station was begun. From a distance of 120 metres, the
vehicles performed a docking manoeuvre. Due to deviations
from the planned procedure for docking, the link-up was
called off. The crew has begun making preparations for a
return to Earth" (Clark, 1988, pp. 104-5). While soft
docking was achieved, hard docking enabling electrical
connections to be made was not. This failure resulted in the
prohibition of all-rookie crews and Romanenko and
Ivanchenkov from the all-rookie back-up crew were each
paired with veteran cosmonauts.
Another failure occurred in April 1983 with the
aborted Soyuz T-8 mission. Although the launch shroud
accidentally removed the rendezvous radar antenna, mission
controllers decided to violate their own rules and let Vladimir
Titov attempt an optical rendezvous from 10 km. This had
never been done before by the Soviets and was particularly
risky since Titov later claimed he had not previously trained
for manual approach and docking. Flight directors assisted
Titov by computing the range rate after Titov reported Salyut
size estimates. After a range of 330 meters was passed, the
Soyuz slipped out of contact with the ground. Without his
range rate source, Titov was not sure of his closing rate.
Although he was able to reduce his range to 75 meters with
the aid of the Soyuz's floodlight, he approached at too high a
velocity and fearing a collision, fired thrusters to change
orbits and abort the docking (Newkirk, 1990).
"There had been ten manned launches to Salyut 1,
Salyut 3, Salyut 4 and Salyut 5. Of these one had failed to
reach orbit (Soyuz 18-1), two had failed to dock with their
Salyuts (Soyuz 15, Soyuz 23), one had docked but the crew
had been unable to transfer to their Salyut (Soyuz 10) and
one crew had perished during their return to Earth (Soyuz
11). This left the Soviets with a 50 per cent success rate, if
we deem Soyuz 21 as a successful mission even though it
was terminated earlier than planned. . . . During 1977-1981
there were 16 Soyuz spacecraft launched towards Salyut 6
and of these only one failed to dock (Soyuz 33) and one
docked but the crew could not transfer (Soyuz 25);
additionally, there were 4 launches of Soyuz-T craft, 12
launches of Progress craft and the Cosmos 1267 mission P
all of which successfully docked with Salyut 6. For Salyut
6 the success rate was 94 per cent" (Clark, 1988, pp. 126-
7).
Docking Recoveries
Not all failures resulted in the loss of the mission.
During the Soyuz T-6 mission in June 1982, Vladimir
Dzhanibekov rescued the docking with a manual maneuver
after the automatic system failed. After turning the
spacecraft around to perform the braking maneuver, at 900
meters from Salyut 7, the Argon computer failed and would
not realign with the station. Dzhanibekov disconnected the
computer and maneuvered the Soyuz along all three axes to
resume pointing at the station. His successful docking from
such a far range under manual control was a major
achievement (Newkirk, 1990). The regular failure of the
Soyuz-T system during final approach was usually followed
by manual recovery and presumably led to computer
improvements in Soyuz-TM (Clark, 1988).
Vladimir Dzhanibekov was no stranger to docking
operations as this was his third. After five flights (he is the
first, and as of 1986 still the only, cosmonaut to fly more
than three missions), he is the Soviet Union's most
experienced cosmonaut. Dzhanibekov served as back-up
commander to Alexei Leonov for ASTP but did not fly until
January 1978 with Soyuz 27 when he achieved the first
double docking with a manned space station. In March 1981
he flew his second flight in Soyuz 39 with Jugerdemidiin
Gurragcha. In July 1984, on Soyuz T-12, he accompanied
Svetlana Savitskaya in the first extra-vehicular activity
(EVA) by a female (Hillyer, 1986).
As prime commander of the Soyuz T-13 mission,
Dzhanibekov had the privilege of testing a new manual
docking system in June 1985. The primary purpose of this
flight was to rescue Salyut-7 after it had lost all power and
was rolling aimlessly in space. As Dzhanibekov says,
"There were great difficulties with preparation for docking
with this object. The station seemed to us as a dead space
object and nothing more. And specialists were afraid that it
would rotate in space at too high a speed in three axes. So
we had to train and to find out this optimum way to
maneuver around the station to find the best light conditions
of the Sun. And of course to train our hand . . . everything
had to be done manually" (Hillyer, 1986, p. 17).
Equipped with a laser rangefinder, Dzhanibekov
compared the measured range to Salyut-7 with the range
computed by his spacecraft. At 10 km, Dzhanibekov
interrupted the automated approach to input Salyut 7 attitude
data into the Soyuz docking computer. The automatic
approach resumed until "3 km distance, at a rate of 12, and
later 6 meters/second when Dzhanibekov took control"
(Newkirk, 1990, p. 270). At three km, "there started to be a
difference between our measurements and the radar-
calculated data. So I had to take the handles and step in to
direct manually" (Hillyer, 1986, p. 17). "At 2 km, the crew
used a new optical guidance system, hand-held laser range
finder and a night vision instrument, to see and measure
distance to the station" (Newkirk, p. 270). At a range of
200 meters, Dzhanibekov nulled the approach velocity
because the sun was behind the station making visibility
poor. For 10 minutes he circled the station on damage
patrol. Then, in a roll-matching maneuver, he docked with
the station. "(Later Dzhanibekov would say, TDocking is
like driving a seven-ton truck with fragile freight on an icy
road into a narrow gate at the end of this road')" (Kramer,
1990, p. 57). The docking was successful and Dzhanibekov
has similar opinions about manual control as Buzz Aldrin.
He shares Aldrin's skepticism about automated systems and
claims that manual control gives the ability to "operate in
wider range" (Hillyer, p. 18).
Admittedly, one of the main reasons for manual
control is emotional or political, namely, pilots would rather
fly than watch. However, the successful rescues mentioned
previously would not have been possible without human
intervention.
Another recovery was made with Soyuz TM-5 (the
thirteenth international crew-Bulgaria), in June 1988.
Although the Kurs system malfunctioned during the final
approach, flight controllers diagnosed the problem and a
successful docking was completed within two days of the
launch.
In June 1990, a docking recovery was achieved with
an unmanned vehicle. Docking of the Kristal module with
the Mir space station was automatically aborted when a
Kristal computer discovered a malfunction in one of its
attitude control thrusters. Ground controllers used a backup
set of thrusters to complete the docking operation
successfully (Rains, 1990a).