Xref: utzoo sci.space.shuttle:6955 sci.space:26658 Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!sun-barr!lll-winken!unixhub!shelby!eos!brody From: brody@eos.arc.nasa.gov (Adam R. Brody) Newsgroups: sci.space.shuttle,sci.space Subject: Soviet docking (4 of 4) Keywords: Soviet docking Message-ID: <7741@eos.arc.nasa.gov> Date: 26 Dec 90 19:02:46 GMT Followup-To: sci.space.shuttle Organization: NASA Ames Research Center, California Lines: 24 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).