DOCKING AND EXTRAVEHICULAR ACTIVITY (EVA)

For space station missions Buran would have carried a Docking Module (SM) in the forward part of the payload bay. It consisted of a spherical section (2.55 m in diameter) topped by a cylindrical tunnel (2.2 m in diameter) with an APAS-89 androgynous docking port, a modified version of the APAS-75 system developed by NPO Energiya for the 1975 Apollo-Soyuz Test Project. The spherical section, bolted to the floor of the cargo bay, had two side hatches, one connecting it to Buran’s mid-deck and the other providing access to the payload bay for spacewalking cosmonauts or to a Spacelab-type module. The tunnel provided the actual interface between the Docking Module and the target vehicle and would be extended to its full length after opening of the payload bay doors. With the tunnel fully extended, the adapter was 5.7 m high. If the extendible part of the tunnel became stuck in its

deployed position, it could be pyrotechnically separated to allow the crew to close the payload bay doors.

At least one flightworthy SM was built for the first mission of flight vehicle nr. 2, which would have featured a docking with Mir and a Soyuz TM spacecraft. The Buran Docking Module served as the basis for a small module that was supposed to be attached to the Mir-2 space station to act as a berthing place for Soyuz, Progress, and Buran vehicles and as an airlock for spacewalks. It would be towed to the station by a detachable Progress-M propulsion compartment. The module was eventually launched as Pirs to the International Space Station in September 2001 (see Chapter 8).

During missions not involving dockings, Buran would have flown with an internal airlock in the mid-deck. The EVA spacesuit used by the cosmonauts would have been a modified version of the semi-rigid Orlan spacesuit, originally developed in the 1960s for the Soviet piloted lunar program. Developed by the Zvezda organ­ization in Tumilino, it would have been worn by the cosmonaut who was supposed to stay behind in lunar orbit aboard the LOK mother ship to assist his colleague in spacewalking to the lunar lander before landing and back to the LOK after ascent from the lunar surface. The Orlan was a simplified, lighter version of the moon – walker’s Krechet suit. Unlike the Krechet, it was not completely self-contained (being connected to the spacecraft’s power systems with an umbilical) and designed for relatively short spacewalks.

After cancellation of the lunar program a modified version of the suit known as Orlan-D was developed for EVAs from the Salyut-6 space station, launched in 1977. The modifications were mainly related to the fact that the suit had to remain in orbit for a long time, be serviceable, and be worn by different cosmonauts. In October 1980 NPO Energiya and Zvezda reached agreement on using the same Orlan-D for space­walks from Buran. The suit and airlock could support up to three 5-hour EVAs during a 7-day Buran mission and from six to eight EVAs during a 30-day mission.

In March 1984 Zvezda was ordered by MOM and MAP to start development of a jet-powered backpack, giving cosmonauts more flexibility during spacewalks. Interestingly, the order came just one month after the first use of the analogous Manned Maneuvering Unit (MMU) on Space Shuttle mission 41-B. Called 21KS or SPK (“Cosmonaut Maoeuvering Unit’’), the device was intended for spacewalks both from the Mir space station and Buran. One of the main functions that the Russians had in mind for the unit was to allow spacewalking cosmonauts to inspect Buran’s heat shield in orbit. Two of the units could be installed aboard Buran, one on the starboard side of the cargo bay, the other on the port side.

The development of the 21KS also required Zvezda engineers to design a compatible, fully self-contained spacesuit called Orlan-DMA. This no longer had an electrical umbilical connecting it to on-board systems and was equipped instead with a special unit containing power supply, radio communications, and telemetry systems. In 1987 the final decision was made to use this suit in the Buran program instead of the Orlan-D.

Although the Orlan-DMA saw extensive use by Mir spacewalkers between 1988 and 1997, the 21KS was flown only twice by cosmonaut Aleksandr Serebrov from

Mir in early 1990. Since the station could not maneuver to retrieve him if he became stranded, Serebrov remained attached to the station by a 60 m long safety tether. Untethered spacewalks with the 21KS would probably have been authorized only for the Buran program, with the cosmonaut being able to venture 100 m from the vehicle.

In 1992 Zvezda and the German Dornier company studied the feasibility of jointly developing a European-Russian spacesuit for the European Hermes space – plane, Buran, and the then still planned Mir-2 space station. The work on the joint suit (“EVA Suit 2000”) continued after cancellation of those programs in 1993, but

ESA backed out the following year because of financial constraints. The Russian suit now used on ISS is the Orlan-M, a further modification of the Orlan-DMA [27].