FLUG REVUE June 2003: Spacesuits from US and Russian production

SPACE SUITS FROM EAST AND WEST

By Gerhard Kowalski

Russia has been building such “scaphanders” (the word comes from the Greek and originally was a term for “diving suit”) for over 50 years since 1952, when the Zvezda Scientific Production Enterprise (NPP) was founded in Tomilino, just outside Moscow. The first systems were Cover FR 6-2003

developed for experimental animals, mainly dogs, in high-altitude rockets. After this came the life support system for Laika, the first living creature, a female dog, to go to space, in 1957. From 1959, the company worked on scaphanders for Yuri Gagarin and his colleagues, who were launched into space in the Vostok and Voskhod capsules.

Zvezda also produced the inflatable airlock and the scaphander in which in March 1965 Alexei Leonov became the first man to “walk” in space, as well as the space suits for the manned Russian lunar programme which, however, was subsequently cancelled. The lunar suits ultimately served as the foundation for a portable life support system suitable for space walking that was used for the first time on the Salyut 6 space station and was subsequently designated the Orlan-DMA (D for durable, M for modernised and A for autonomous).

From 1997, the Russians used the Orlan-M (modified), the follow-up model to Orlan-DMA, for extra-vehicular activities (EVA) in their MIR laboratory. The first astronauts to wear this suit were the Russian Vasily Tsibliev and his American colleague, Jerry Linenger, on 29 April 1997. Orlan-M incorporated a number of improvements compared with its predecessor. Thus, two elbow and two knee joints provided increased mobility, and, to extend the viewing angle, an extra work lamp was mounted on the helmet. Moreover, the thermal insulation of the visor was improved so that it no longer misted up. Thanks to improved air filters, it now became possible to work for stretches of nine hours wearing the suit instead of seven.

The modified variant of the suit, which retained the name of Orlan-M, was “baptised” on 8 June 2001, when Yuri Usachev and James Voss performed a 19 minute EVA inside the transfer compartment of the Service Module with the hatch open. The first real spacewalks were undertaken by Vladimir Deshurov and Mikhail Turin of the third ISS resident crew on 8 and 15 October 2001.

The following is a list of the major changes in the ISS version of the Orlan-M compared with the one used in the MIR space station:

Better, energy-saving and quieter fans.
Duplex radio communication enabling two cosmonauts to speak and listen simultaneously.
Enlarged metal foil layer, facilitating entry and exit from the hatch at the rear and also making it suitable for larger astronauts.
Electrically powered rescue unit (ustanovka samospasenya kosmonavtov - USK), enabling the astronaut to get back to the station if inadvertently he has been driven away from it.
Onboard systems that allow spacewalks from the Russian Pirs docking module and also from the US airlock chamber Quest.
Installation and/or adoption of some American elements, including water bottle, spectacles, socks, underwear (including Pampers nappies) and glove pockets.

The pressure of the oxygen atmosphere is 0.4 atmospheres. The water-cooled undersuit can be regulated between 8ºC and 25ºC, while the temperature inside the space suit is adjustable between 15ºC and 20ºC. The carbon dioxide from the expired air is absorbed through a lithium cartridge.

The new Orlan-M is designed for astronauts between 1.65m and 1.9m tall. There are articulated joints at shoulder, elbow and knee height. The gloves are removable and there is even a device enabling one to dab the sweat from one's nose and forehead, which is useful since it is not possible to touch one's face with one's hands.

Both the Russian space suit and the American extra-vehicular mobility unit (EMU) are permitted in the ISS. Due to the size of the EMU it is only possible to spacewalk with it from Quest. The main differences between Orlan-M and EMU are as follows:

In the EMU the pressure is only 0.3 atmospheres.
Due to the higher atmospheric pressure, the desaturation process is faster and simpler in the Orlan-M so that a prebreathe period of only 30 minutes is required. (Saturation refers to the saturation of the cosmonaut's blood with carbon dioxide; desaturation is the reverse process.) This compares with up to 12 hours in the airlock or up to four hours in the EMU for the Americans.
Orlan-M is designed so that the cosmonaut can get into it on his own. By contrast, it is difficult to get into the EMU unaided even when one is using the special equipment provided for this purpose.
Orlan-M has a guaranteed lifespan of four years and is maintained in space, whereas a maximum of 25 spacewalks within a period of 180 days is permitted by the manufacturer of the EMU, Hamilton Sunstrand, before it has to be returned to Earth for maintenance.
On the Orlan-M it is possible to shorten or lengthen the arm and leg sheaths, so that the space suits can be individually tailored to a particular cosmonaut. Only the gloves come in predefined sizes. On the EMU on the other hand there are nine different sizes, four of which are normally used.
The Orlan-M weighs 110kg. Its foil layer is made out of an aluminium alloy, whereas on the EMU corrosion-resistant steel is mainly used. It weighs 136kg – and that is without counting the Simplified Aid for EVA Rescue (SAFER) emergency unit which can be attached to the EMU and operates with compressed gas.
All the systems on the Orlan-M are duplicated: the thermal insulation layer, the fans, the water pumps, the pressure regulators, the headsets. There is also a reserve oxygen balloon. The metallic foil layer and helmet have a rubber lining, while the helmet uses duplex glass. The Americans on the other hand regard the EMU as totally failsafe and therefore do not bother with any reserve systems.
As the gloves on the Orlan-M are not electrically heated, unlike the EMU, the Russians have recently acceded to an American request to increase their thermal insulation.

From page 36 of FLUG REVUE 6/2003

Last updated 12 May 2003

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