Housekeeping in an underwater habitat is a crucial part of habitability. It plays a primary role in maintaining the cleanliness of the habitat and thus the crew’s health and safety, which will consequently boost their morale, comfort, and productivity.
The focus of this section is on the removal of unwanted materials such as dust, lint, liquids, and other debris and contaminants from the habitat. This may be from the air or air filtration devices, or from accessible surfaces located in the crew’s living quarters, work facilities, and other habitable areas in the underwater environment, including the habitat itself, surrounding water and seabed. Consideration should be given to various contaminants of the marine environment and how they can be removed safely, effectively, and efficiently from the crew’s habitable environment through routine housekeeping activities. These activities should not require communication with the land base, use of non-housekeeping tools, or complex procedures. Typical housekeeping tasks for a crew might involve periodic cleaning of air filters and wiping down frequently used surfaces such as handrails, galley areas, walls, toilets, and exercise equipment with microbial or disinfectant wipes to prevent dust or bacterial or mold growth from accumulating.
It should be taken into account, that the humidity of an underwater habitat presents a potential risk and has to be strictly monitored. Dehumidification devices must be installed and operable.
Some of the results of this section will have an influence on habitat design, selection of materials and layout of furnishings.
Habitat Specific Risk Areas
Special attention is required on underwater habitat specific risk areas. As there are:
- Moonpool – floating waste on the water surface; mold on the edges of the moonpool over and under water;
- Access tunnel – walls will be rapidly inhabited by algae; suspended matters will settle on the floor grids (removable grids necessary for cleaning);
- Outer shell – regular cleaning session to remove algae will be necessary; the usage of a cleaning robot (see pool robots) should be evaluated;
- Diving suits – there should be a corresponding device/layout to dry diving suits and to store them in a dry area.
Housekeeping for habitat and facilities can be mitigated by focusing on the sources of dust, lint, liquids, and other debris and contaminants. The system can then be designed and operated to control these sources and reduce the time devoted to housekeeping. The following are some of the principal sources of microbes, chemicals, and debris that can cause housekeeping problems:
- Crewmembers – Fingernail clippings, hair, dead skin, fingerprints, body fluids
- Clothing – Loose lint, threads, buttons, fasteners
- Dining and Food Preparation Areas – Crumbs, spills
- Maintenance – Loose parts, filings, leaks from disconnected valves, leaking fluids
- Payloads – Animals, plants, chemicals, effluents
- Fluids – Water, drinks, cleaning fluids used for housekeeping
- Body Waste and Hygiene Areas – Soaps, water, urine, feces, vomitus, menses
- Trash – Wet, dry, and hazardous waste
- Damp Surfaces – Condensation, spills, or poor drainage can promote the growth of mold and mildew (This is especially a problem if the surfaces are poorly ventilated or poorly lit.)
- Benthic particles – Sand, stones, algae
- Suspended matters taken into habitat – General waste, algae
Cleaning Materials – Cleaning materials must be effective, safe for use, and compatible with, air revitalization and waste management systems. All cleaning supplies, materials, and fluids used must be compatible with surfaces to which they may be applied, and need to adhere to program requirements for off-gassing and toxicity.
Wipes – There are several types of wipes:
- solution-saturated wipes for general body cleansing or general housekeeping,
- disinfectant wipes/towelettes saturated with a cationic detergent, absorbent mitts,
- dry paper wipes for general housekeeping. Crews prefer a single-step biocide that does not have to be washed off.
In space applications a handle, holder, or gloves are preferred when using biocide wipes as the biocides currently available stain the hands. Space mission crews have requested an aromatic disinfectant. Urine spills were cleaned up satisfactorily by biocide wipes, but removal of the urine odor is especially important. Absorbent mitts are used for chemical spills. For highly toxic or concentrated chemical spills, silver-shield gloves and bags could be used. These gloves and bags possess breakthrough values that allow for long-term storage of toxic substances.
Vacuum Cleaners – Vacuum cleaning systems should have the following features:
- user-friendly for the crew
- easy to maintain and repair
- has container, that is easily emptied
- should have a HEPA filter
- has attachments appropriate for cleaning filters efficiently
- capable of vacuuming dry and wet particulates
- small, to minimize stowage needs
- quiet, to minimize noise concerns
Vacuum cleaners have been used effectively on Skylab, Mir, and the ISS to remove dust, lint, liquids, and debris from surfaces and air filters. On Skylab, the vacuum was also used for removing water from the shower walls. The ISS wet/dry vacuum cleaner (with bags) contains a HEPA filter to capture small particulates. It also can contain both wet (up to 24 ounces) and dry nontoxic debris (up to 100 cubic inches) and has a nominal operating life of 10,000 hours.
Housekeeping Minimization Through System Design
Housekeeping should be minimized initially through proper attention to system design features. Consider the following spacecraft/habitat design factors to minimize the hazards from contamination and the time and resources required for housekeeping:
- Surface Materials – Materials used for exposed interior surfaces must be selected to minimize particulate and microbial contamination and be easy to clean (i.e., smooth, solid, nonporous materials such as plastic or metal, biocide-impregnated fabric).
- Grids and Uneven Surfaces – Grids and uneven surfaces should not be used or they should be easy to remove for easy cleaning (e.g., grid floors).
- Cracks and Crevices – All interior structural surfaces and equipment should be free of narrow openings and crevices that can collect liquid or particulate matter or that require special cleaning tools.
- Closures – Closures should be provided for any area that cannot be easily cleaned.
- Condensation – Condensation must be prevented from persisting on surfaces, in order to reduce bacterial growth.
- Filters – The filters should be easily accessed for them to be cleaned
- Trash Management – See corresponding section
- Body Waste and Hygiene Areas – Body waste and hygiene areas should be designed with maintenance and cleaning in mind. Efficient design of these areas can greatly reduce the amount of cleaning fluid and body fluids released into the environment and allow the crew to perform hygiene functions in a manner that will reduce the need for additional housekeeping.
- Dining and Food Preparation Areas – These areas must be designed to prevent growth of mold and bacteria while promoting easy maintenance and cleaning.
Past and Present On-Orbit Housekeeping Operations
The information provided below concerning the ISS, Mir, Skylab, and Space Shuttle housekeeping subsystems is derived from the Space and Life Sciences Flight Crew Support Division’s document, Comparison of Mir, Shuttle and ISS Habitability (Campbell, 1995).
- ISS U.S. Segment – The ISS U.S. Segment housekeeping subsystem supports routine cleaning with the use of a portable wet/dry vacuum cleaner, six kinds of wipes (which are consumable and resupplied with each mission), detergent, wipes cartridges, and dispensers for the cartridges and detergent. All crewmembers perform housekeeping tasks as needed or during the 4 hours a week that housekeeping is scheduled.
- Mir – Mir housekeeping involved 1 day of general housekeeping, usually scheduled on Saturday. The equipment and consumables used to support cleaning and elimination of contamination on surfaces aboard Mir included a vacuum cleaner, a surfactant/disinfectant, and wipes. A typical weekly task would be for the entire crew to wipe down the entire core module with wipes and antiseptic solution. Not all Mir surfaces and locations could be reached for cleaning with wipes and cleansing agent. Mir did have a large amount of microbial growth on board, in part because of the design of the environmental system. The thermal control system also contributed to microbial growth because it had cold spots that would condense moisture in stagnant areas.
- Space Shuttle – A main focus of the Space Shuttle’s housekeeping subsystem involves cleanup of contamination in the crew cabin. This subsystem provides a vacuum cleaner, wet and dry wipes, biocide cleanser (a liquid detergent formulation of soap, Lysol, ethanol, and water), dispensers for wipes and cleanser, and disposable gloves. On several early Space Shuttle flights, beginning with STS-5, debris issues were identified. By STS-7, “filter cleaning” became a scheduled maintenance activity. The task was time-consuming (2 hours) because it involved removing several panels of the flight deck to clean several different air filters and screens. This routine task was conducted at least 3 times during the 14-day flight.
- Skylab – Housekeeping aboard Skylab mainly entailed the cleaning and removal of contamination in the spacecraft interior. It included the use of a vacuum cleaner, 4 types of wipes, a biocide, and disposable plastic gloves. Typical housekeeping tasks on Skylab were the frequent cleanup of food and beverage spills. Wet rags were used for food messes and spills because they were considered to be more absorbent. The long durations (28 to 84 days) of the missions made it especially important to attend to the air filtration aspects of housekeeping, to avoid crew illness through air contamination.
This article contains adaptations from the NASA Human Integration Handbook (HIDH), NASA/SP-2010-3407. NASA copyright policy states that “NASA material is not protected by copyright unless noted”. (See NASA copyright policy page or JPL Image Use Policy.)
Entry image: Rlistmedia, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons