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When you look at a Soyuz, it seems like the descent and orbital modules are covered in some kind of fabric-like material. You can see wrinkles and it does not look like traditional metal as you might expect, for something that needs to survive reentry. Surely the heat shield takes the brunt of the heat load, but some heat clearly leaks over the edge to the sides.

   enter image description here

   TMA version of the Soyuz spacecraft (Photograph source: Wikimedia Commons, credit: NASA, click on photo for full resolution)

TildalWave
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geoffc
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    I suspect its a kevlar blend. I saw a documentary on the future space station possiblities and they talked about a kevlar blend they could wrap the modules in to absorb small impactors. – Chad Dec 30 '13 at 22:37

2 Answers2

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The outside of the Soyuz is covered in multilayer vacuum-screen thermal insulation. Its Russian acronym is ЭВТИ, long for экранно-вакуумная теплоизоляция or Shield Vacuum Thermal Insulation. It apparently is in many layers of metalized film and fiberglass cloth.
Its purpose is to protect the modules during ascent and orbit. It doen't seem to be designed to survive reentry: in photos of the descent module post touchdown, this material is not intact. Soyuz descent module post touchdown

Hobbes
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  • To the person who tried to edit this: if you say the material has "almost completely disappeared", that means most of the layers are gone. I found no documentation that says how many layers are left, so that would be an unsupported statement. 50% of the layers could still be there. – Hobbes Jun 05 '17 at 13:11
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The book "Soyuz: A Universal Spacecraft" by Rex Hall, David Shayler (2003) has the text on page 41:

Propulsion Module, ... Descent module, ... Orbital Module... materials used in the fabrication of these modules .... an aluminium alloy was finally chosen. The thermal insulation covering the modules consists of two layers - the upper layer consisting of an asbestos-cloth laminate, and the lower layer of 'a light, heat-insulating material'.

"Leaving Earth: Space Stations, Rival Superpowers, and the Quest for Interplanetary Travel" by Robert Zimmerman (2003) says at page 280:

Protecting Soyuz-TM's bell-shaped descent module were eight blankets of insulation material, each made of many layers of golden foil and an outer micrometeoroid layer.

(note, "golden foil" may describe polymer film, covered by thin layer of any metal)

There were several EVAs to fix some equipment under "vacuum-screen thermal insulation" (EVTI), like by Titov and Monarov (30.06.1988, 20.10.1988, page 254 of Leaving Earth) fixing X-ray telescope TTM "Roentgen" on Kvant-1 (Mir Space station). Or EVA on ISS by Expedition 17 (10-11.07.2008; Orlan spacewalk EVA-20A)

osgx
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