Xref: utzoo sci.space.shuttle:6952 sci.space:26655 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uwm.edu!lll-winken!unixhub!shelby!eos!brody From: brody@eos.arc.nasa.gov (Adam R. Brody) Newsgroups: sci.space.shuttle,sci.space Subject: Soviet Docking (1 of 4) Keywords: Soviet docking Message-ID: <7738@eos.arc.nasa.gov> Date: 26 Dec 90 18:05:14 GMT Followup-To: sci.space.shuttle Organization: NASA Ames Research Center, California Lines: 12 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).