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Soyuz ASU

Some information about the Soyuz ASU, toilet – a somewhat indelicate but necessary topic!

The waste disposal system functions similarly to the ISS toilet in the Russian segment – using a vacuum system – though everything is necessarily more compact. It resides in the Soyuz Orbital Module. The descriptions below are derived from those at Charles Simonyi’s site (I can’t link to the relevant pages directly as it is a Flash-animated site – grrr!).

For urination (with the control panel switch set to #1) a replaceable funnel is used. The waste is sucked into a collection tank (there are ten in the module), and the air circulates through a charcoal filter before being sent back into the cabin. According to this post at CollectSPACE.com, “women use a sanitary-napkin-type pad which absorbs fluid,” which doesn’t sound too appealing! If the electric air pump fails, a device with a rubber-bulb handpump serves as a backup.

For defecation (switch set to #2), a disposable bag is put into a container, which has an air suction tube connected to the container (the airflow goes through the bag and a charcoal filter). A carton cover needs to be removed from the bag before insertion; it contains some sanitizing chemicals and toilet paper (the latter is also removed). The user positions the device against their posterior. After finishing, a string around the edge of the bag snaps a rolled rubber cover into place, hermetically sealing the contents. After securely tying it with rubber ties (similar to the ones used to tie up the lining of the Sokol spacesuit), the bag insert is removed and put into another rubberized bag. This is placed into yet another bag, hermetically sealed and placed in a waste container with other rubbish (it will all burn up when the Orbital Module is discarded upon descent).

SoyCOM Manual: Ассенизационно-Санитарная Установка (АСУ) (Waste Management System)

АСУ function is collection, isolation and stowage of the crew’s physiological wastes.

АСУ composition:

In the БО:

  • solid /liquid waste collector;
  • wring receptor;
  • urine collector;
  • filter/fan;
  • АСУ panel;
  • inserts and replaceable rings.

In the СА:

  • urine collector (3 pcs.);
  • terminal;
  • replaceable rings.

АСУ Technical Characteristics:

  • System service life: 12.6 man-days;
  • Collector capacity: 10.8 l;
  • Fan air flow rate: 250±30 l/min;
  • Rated one-man daily urine excretion: 1.2 l.

Diagrams & photo links

Some photos of the Soyuz toilet at Skorina.com: 03.24 20Jun00; 03.25 20Jun00; 05.06 21Jun00.

The following diagrams are from « Когда невесомость в тягость, о чем молчат космонавты» (“When weightlessness is a burden, about which the cosmonauts keep silent”), Russian Popular Mechanics, June 2006 – on the development of Russian space toilets. (Thanks to “Captain David” for finding this!)

  • ASU schematic of the Soyuz transport spacecraft. In the case of unforeseen circumstances in the Soyuz spacecraft, there are two emergency subsystems for the collection of urine. If fan (neither in the automatic nor in the manual regime) does not work, it is possible to create the necessary rarefaction with the aid of the rubber bulb. But if after the shooting of everyday section cosmonauts on some to reason are detained in flight, they can use a spare urine dump.

    Diagram translation:

    Емкость для сбора мочи
    Urine collector
    Дезодорирующий фильнр
    Deodorant filter
    Запасной мочеприемник
    Reserve/backup urine collector
    Резиновая груша
    Rubber squeeze-bulb
    Резервный мочеприемник с отжимом
    Reserve urinal with extractor
    Приемник твердых отходов
    Solid waste receiver
    Приемник жидких отходов
    Liquid waste receiver
  • A reserve urine dump with a rubber squeeze-bulb is utilized in the case of a failure of the fan.
  • The spare urine dump will facilitate the life of cosmonauts in the Descent Module after the Orbital Module is detached on re-entry. A cap is used to hermetically seal the entrance and guarantee hygiene; it resembles a small condom.
  • An insert for solid waste is used aboard the Soyuz spacecraft (with the closed shutters). For the ISS adaption, simpler and lighter inserts made from polymer film are used, in particular because the leakages of waste from the inserts are not disasterous there (they are sucked into a disposable container).
Soyuz loo (African in Space)
“This charming layout shows a Soyuz space toilet. Primitive, but apparently quite effective. In general the crews try not to have to use the solid waste receptacle on trips to and back from the ISS.”
Soyuz toilet components (Charles in Space)
Soyuz toilet components (Charles in Space)

Related page: ISS SGO