Soyuz-T-1 Spacecraft Series
By Marcia S. Smith, Formerly with the, Science Policy Research Division of the Library of Congress, Congressional Research Service
II. THE SOYUZ-T PROGRAM
Soviet Manned Space Programs: 1957-80
SOYUZ T AND RELATED DEVELOPMENT FLIGHTS
In December 1979, the Soviets introduced a new, improved version of the Soyuz spacecraft, designated Soyuz T.18 At least three unmanned precursor flights (Kosmos 869, 1001, and 1074) had already been flown, and the first Soyuz T flight so identified was also unmanned. Two additional flights, Kosmos 670 and 772, may also have been related to the development of Soyuz T. These flights are summarized in table 7.
Kosmos 670 was launched on August 6, 1974, into a 307 X 217 km orbit, and was recovered three days later. It was unique in that its inclination was 50.6 degrees, never before used on a flight launched by an "A" class vehicle, and was, in fact, close to that which Western rumors had predicted would be used for the big "G" class vehicle. Otherwise, its external flight parameters seemed close to military recoverable observation flights. There was speculation that this might be a test of a ferry vehicle to a new large space station which would be orbited using the "G" vehicle at some future time. With hindsight, it has been classified here with the Soyuz T precursors.
On September 29, 1975, the Soviets launched Kosmos 772 into a 320x201 km orbit, inclined at 51.8 degrees. Soyuz-type telemetry on 20.008 MHz was monitored in Kettering and Akrotiri, Cyprus. Like the Soyuz ferry ships, Kosmos 772 had no solar panels, but remained in orbit for 3 days like Kosmos 670, a day longer than most other missions of its kind, suggesting either greater battery capacity or lessened electrical loads. There was speculation that this might be a system test for returning to a three-person crew.
KOSMOS 869, 1001, AND 1074
On November 29, 1976, the Soviets launched Kosmos 869 into an orbit 307x202 km at an inclination of 51.8 degrees. The spacecraft made several orbital maneuvers during its 18 days in orbit, raising perigee to 299 km. Kosmos 1001 was launched on April 4, 1978 into an initial orbit of 249x205 km at 51.6 degrees inclination. This was later raised to 315x308 km. It was deorbited on April 15. Kosmos 1074 was launched on January 31, 1979 into a 258x203 km orbit inclined at 51.6 degrees. This was later raised to 383x364 km. The spacecraft remained in orbit for 60 days, reentering on April 1. All of these are now considered to have been related to development of Soyuz T.
Finally, at 1230 GMT on December 16, 1979, the Soviets launched Soyuz T-l (see figure 26). This was an unmanned test of the new spacecraft and at 1405 GMT December 19, the craft docked with Salyut 6. Unlike previous dockings, the Soyuz T rendezvoused from above and in front of Salyut, rather than catching up with the station from behind, (19) and it docked at the forward docking hatch. Geoffrey Perry of the Kettering Group has determined that Soyuz T overshot Salyut on the second day (rev 32) and had to be maneuvered back for a rendezvous and docking on the third day (rev 50). This is the only time 3 days have been required for a rendezvous with a space station (a manned Soyuz normally takes 1 day while unmanned Soyuz and Progress missions take 2). At 2104 GMT on March 23, Soyuz T-l undocked from Salyut 6. After 2 more days of autonomous tests, the spacecraft landed on March 25 at night in Kazakhstan (2150 GMT).
FIGURE 26,—Soyuz T Ferry Craft. The Soyuz T variant of the Soyuz spacecraft series has been extensively redesigned internally to permit carrying up to a crew of three to the Salyut space stations.
Following this flight, more information became available about the new craft. Externally, Soyuz T is the same as the original Soyuz: 7.6 meters long, 3 meters in diameter, with a launch weight of 6.5 tonnes. A number of modifications have been made to the ship, however.
One significant change is the return to the use of solar panels. As noted earlier, the solar panels were removed beginning with Soyuz 12 on the theory that the ship would only have to remain in a free flying mode during the journey up to and down from a space station. Thus battery power would be sufficient, and the panels could be removed to allow a greater weight margin for payloads. After several docking failures (Soyuz 15, 23, 25), however, the Soviets apparently saw the need to give the Soyuz a longer lifetime on its own to deal with contingencies. In addition, once the spacecraft docks with Salyut, the two solar power systems are combined to provide additional power for space station operations.
The fuel system has been redesigned so that the main engine and all four attitude control thrusters can use the same fuel supply, meaning that the attitude thrusters can serve as a backup to the main engine in an emergency. Previously, a faulty maneuver could exhaust the supply of fuel in the orientation system while the main engines had plenty, (20) and in the original Soyuz, the main engines used hydrazine, while the attitude control thrusters used hydrogen peroxide.21 The new unified system, which is also used on Salyut and Progress, also results in higher thrust and maneuvering capability. Two changes made in the descent/landing phase are: (1) the orbital module separates before retrofire instead of after as had been the case with Soyuz, thus saving 10 percent of the fuel since there is less mass to decelerate; and (2) the landing engines have more thrust to provide for a softer landing.
Among the changes in avionics is the introduction of a digital computer called the Autonomous Onboard Computing Complex which can fly the mission without human involvement. The computer has a CRT display unit, and analog sequence control devices previously used on Soyuz have been removed, while the number of indicator panels has tripled. A periscope is still used for the cosmonauts to orient themselves in space.22 Soyuz T also has improved telemetry rates and channels for more reliable communications with the flight control center and tracking ships.
The rescue system mounted on the nose of the spacecraft has been improved, too, so. that if a malfunction occurs during launch and initial flight, the launch vehicle main engines are automatically switched off, the spacecraft is separated from the booster, and the rescue rocket engines are ignited for a controlled emergency landing.
The interior has been redesigned to accommodate three space suited cosmonauts, and the first mission to carry three was Soyuz T-3, nearly 10 years after the ill-fated Soyuz 11 mission. The commander sits in the center, with the flight engineer to his left and the research engineer to his right.
For all its advances, the Soyuz-T still has some hurdles to overcome. On the first manned flight of the vehicle, Soyuz T-2, the cosmonauts had to abort the computer-controlled docking and take over manually starting at 180 meters from the station.23 Soyuz T-3 was more successful.
A. SOVIET SPACE PROGRAMS: 1976-80, (WITH SUPPLEMENTARY DATA THROUGH 1983) MANNED SPACE PROGRAMS AND SPACE LIFE SCIENCES PREPARED AT THE REQUEST OF HON. BOB PACKWOOD, Chairman, COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION UNITED STATES SENATE, Part 2, OCTOBER 1984, Printed for the use of the Committee on Commerce, Science, and Transportation, U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON, D. C., 1984
16. Pravda, Sept. 16, 1976.
17. Spaceflight, Feb. 1977, p. 62.
18. The T stands for Troika to indicate that it is a third-generation spaceship, Soldat und Technik, No. 8, Aug. 1981, p 453.
19. Spaceflight, Nov.-Dec. 1980, p. 344.
20. Moscow World Service in English, 0700 GMT, June 6, 1980
21. Air & Cosmos, Jan. 26, 1980, pp. 46-47.