Voskhod Program - astronomy.

Voskhod Program - astronomy. I INTRODUCTION Voskhod Program, piloted space program of the Union of Soviet Socialist Republics (USSR) that took place during the mid-1960s. The Voskhod program (voskhod means "dawn" in Russian) was designed to keep the USSR competitive in the space race with the United States while the USSR developed Soyuz, its first spacecraft built specifically for piloted flight. Voskhod, a two- or three-cosmonaut spacecraft, was based on the one-cosmonaut Vostok spacecraft, which in turn was based on a spy satellite design. The Voskhod program began as the United States announced in late 1961 that it would soon begin two-astronaut Gemini program flights. Soviet leader Nikita Khrushchev demanded that his engineers keep ahead of the United States in space at all costs. To do this, they modified Vostok, a simple spacecraft much like the U.S. Mercury spacecraft, to permit it to accomplish tasks like those of Gemini. Despite its improvised nature, the Voskhod program accomplished the first three-person spaceflight (on Voskhod 1) and the first spacewalk (on Voskhod 2). Engineers planned a series of Voskhod flights, including a week-long flight and a flight with two female cosmonauts that would include a spacewalk. However, after Khrushchev's fall from power--which occurred while Voskhod 1 was in orbit--the new leadership permitted only one more Voskhod flight because it wished to devote its resources to hastening the development of Soyuz spacecraft. II SPACECRAFT The Voskhod spacecraft outwardly resembled the earlier Vostok spacecraft, but it required many changes in order to support spacewalks and flights by more than one cosmonaut. Voskhod climbed into space on a modified Vostok rocket. Fitting more than one cosmonaut into the spacecraft's small space meant leaving off the Vostok ejection system, so the cosmonauts could not escape if the rocket had trouble on the launch pad, as early rockets often did. In fact, they could not escape until the rocket climbed above most of the atmosphere and ejected the streamlined shroud covering the capsule. Then they could blast free using the capsule's primary retrorocket. The haste of construction and the parts removed in order to fit another person into the capsule made Voskhod into the riskiest piloted spacecraft ever flown. Like Vostok, Voskhod had two basic parts--a capsule and an equipment module that together weighed about 5300 kg (about 11,700 lb). The capsule was a 2.3-m (7.5ft) silver sphere with a round hatch for the cosmonauts to enter and exit. A second round hatch covered the compartment that held the parachute used for returning to Earth. Four metal straps and a bundle of power and control cables joined the capsule to the equipment module, which was shaped like two blunt cones joined at their bases. Green spherical oxygen tanks ringed Voskhod where the capsule joined the equipment module's top cone. The bottom half of the equipment module was covered by plates of heat-radiating material. The primary retrorocket was mounted on the bottom of the equipment module. A cylindrical backup retrorocket on top of the capsule helped ensure that Voskhod could return to Earth even if the primary retrorocket failed. The backup retrorocket was important because Voskhod operated at a higher altitude than Vostok; this meant that it would not fall back to Earth naturally after ten days, as Vostok would. For the spacewalk on Voskhod 2, a special fabric airlock compartment called Volga was added. The collapsed airlock fit over the crew hatch during launch. In orbit it inflated, forming a tube 2.5 m (8.2 ft) long. The airlock was necessary because Voskhod's electronics were air-cooled. If the entire crew cabin was depressurized to allow the spacewalker to climb outside (as occurred on Gemini) the electronics would overheat. After the spacewalker entered the airlock, the commander closed the hatch behind him, then released the air from the airlock. The spacewalker then opened Volga's outer hatch to enter space. When the spacewalk was complete, the airlock was ejected. The Voskhod spacecraft dropped out of orbit using one of its retrorockets. The equipment module and backup retrorocket detached and burned up in the atmosphere while a heat shield protected the capsule. As the capsule entered the dense lower part of the atmosphere, a single parachute opened. Just before touchdown a special landing rocket attached to the parachute lines fired to soften the capsule's impact with Earth. III MISSIONS A single unpiloted Voskhod mission, called Kosmos 47, preceded Voskhod 1. Kosmos 47 launched on October 6, 1964, to test the modifications made to the Vostok capsule. It landed safely the next day. Voskhod 1 left Earth on October 12, 1964, carrying commander Vladimir Komarov, Konstantin Feoktistov (the engineer who oversaw Vostok's conversion into Voskhod), and physician Boris Yegerov. The mission marked the first flight of a multi-person spacecraft and the first time an engineer or a physician were sent into orbit. Voskhod 1 was so small that Komarov, Feoktistov, and Yegerov could not wear bulky pressurized space suits to protect them if the capsule lost pressure. Because of the cramped conditions and limited time, the cosmonauts could only perform a few medical experiments. The capsule came back to Earth on October 13, 1964. Some sources state that Voskhod 1 was called back early because Khrushchev fell from power. Yegerov and Feoktistov reportedly became ill during the mission due to the physiological effects of space flight (see Aerospace Medicine: Space Medicine). The goal of Voskhod 2 was to beat the United States in performing the first spacewalk. An unpiloted test flight, Kosmos 57, preceded Voskhod 2. Kosmos 57 reached orbit on February 22, 1965, and deployed its Volga airlock. However, something went wrong and the airlock exploded. Nevertheless, Voskhod 2 was launched on schedule on March 18, 1965, because the United States had scheduled the first Gemini spacewalk to occur within months. Voskhod 2 carried cosmonauts Pavel Belyayev and Alexei Leonov. The Voskhod 2 Volga airlock inflated normally and Leonov entered the airlock, then stepped out into open space. The USSR claimed that Leonov's 24-minute spacewalk went well, but it is now known that he nearly died. His suit became stiff and he found it almost impossible to control his movements. Leonov overheated, then became stuck sideways in the Volga airlock. He only freed himself after releasing some of the air from his suit so he could bend--a dangerous, desperate measure. Trouble struck again during the return to Earth. A sensor failed, forcing Voskhod 2 to remain aloft for another orbit while Belyayev prepared for manual reentry. He landed 1000 km (600 mi) off course in snowy Siberia, where the cosmonauts had to wait overnight for rescue and were menaced by a bear. The 26-hour, 2-minute flight marked the end of the perilous Voskhod program. Contributed By: David S. F. Portree Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.