- NASA Home
- > Missions
- > International Space Station
- > Research
- > Experiments
Fact Sheet
Text Size
Overview | Description | Applications | Operations | Results | Publications | Images
Experiment/Payload OverviewBrief Summary
A Comprehensive Characterization of Microorganisms and Allergens in Spacecraft (SWAB) uses advanced molecular techniques to comprehensively evaluate microbes on board the International Space Station (ISS), including pathogens (organisms that may cause disease). SWAB also tracks changes in the microbial community as spacecrafts visit the station and new station modules are added. This study assesses the risk of microbes to the crew and the spacecraft.
Principal Investigator
Payload Developer
Johnson Space Center, Human Research Program, Houston, TX, United States
National Aeronautics and Space Administration (NASA)
Sponsoring Organization:Exploration Systems Mission Directorate (ESMD)
ISS Expedition Duration:April 2006 - March 2010
Expeditions Assigned
13, 14, 15, 16, 19/20, 21/22
Previous ISS MissionsSWAB has been performed on ISS Expedition 13, 14, 15, 16, 19, and 20.
Experiment/Payload Description
Research Summary
- Previous microbial analysis of spacecraft only identifies microorganisms that grow in culture, omitting greater than 90 percent of all microorganisms including pathogens such as Legionella (the bacterium which causes Legionnaires' disease) and Cryptosporidium (a parasite common in contaminated water).
- Scientists have yet to study the incidence of potent allergens, such as dust mites and microbial toxins in spacecraft environments.
- This study uses modern molecular techniques to identify microorganisms and allergens. Direct sampling of the ISS allows identification of the microbial communities present, and determination of whether these change or mutate over time.
- SWAB complements the nominal ISS environmental monitoring by providing a comparison of analyses from current media-based and advanced molecular-based technologies.
During long-duration space flight missions, spacecrafts build up a diverse array of microorganisms that directly interacts with the crew. Most microorganisms are harmless or even beneficial to the crew; however, the presence of medically significant organisms appearing in this environment could adversely affect crew health and performance during long-duration missions. The primary goal of the Surface, Water and Air Biocharacterization?A Comprehensive Characterization of Microorganisms and Allergen in Spacecraft (SWAB) experiment is to use advanced technologies to better understand the types of organisms that the crew encounters, their sources, and assess the potential risks.
This study of microorganisms, allergens, and microbial toxins in the spacecraft environment mitigates the risk to the health, safety, and performance of crewmembers during flight. All previous methods evaluating spacecraft ecology utilize culture-based methodology; thus many organisms are omitted from isolation, including medically significant organisms, such as the pathogen Legionella (the bacteria that causes Legionnaire's disease). Likewise, culturable bacteria and fungi are the only potential allergens studied; the more potent allergens, such as dust mites, are not analyzed in spacecraft environments. This study utilizes modern molecular biology, advanced microscopy, and immunochemical techniques to examine air, surface, and water samples for bacteria and fungi, pathogenic protozoa, allergens, and microbial toxins.
New collection techniques improve the quality of the sample being returned from ISS for analysis. Air samples are collected through a novel gelatin filter to improve collection efficiency. These filters retain particles as small as viruses. Water and surface samples improve deoxyribonucleic acid (DNA) recovery using a DNA preservative that is composed of a mixture of sodium dodecylsulfate (SDS) and ethylenediaminetetraacetic acid (EDTA) in tris (hydroxymethyl) aminomethane (Tris) (an organic compound used as a component of buffer solutions) buffer.
Analysis of the in flight samples focus around molecular techniques. These include bacterial fingerprinting, bacterial and fungal ribosomal identification, and quantitative PCR (polymerase chain reaction) to identify and enumerate specific genes in environmental samples. The identification of specific genes is critical in the assessment of microorganisms for particular characteristics, including the production of microbial toxins. The samples returned from flight are evaluated using Denaturing Gradient Gel Electrophoresis (DGGE), a technique that allows identification of the bacteria without any amplification of the organisms with growth on media. This technique holds the potential to increase the number of different identified species by 100 fold.
Applications
Space Applications
Knowing the microorganisms that the crew encounter is crucial in assessing the health risks of the crew and performance of the spacecraft systems. By studying the types of organisms and the change in this ecosystem over time, preventative and disinfection regiments are developed to mitigate the accumulation of medically significant organisms or microorganisms that foul filters or degrade components of the spacecraft.
Earth ApplicationsThe results of this study provide insight into changes that occur in the microbial ecology of semi-closed systems. The development of specific primers for bacterial enumeration and fungal identification during this study advance the ability of ground-based investigators to diagnose the potential sources of microbial contamination and give insight into the causes of health related microbial contamination issues such as "sick building syndrome."
Operations
Operational Requirements
The SWAB flight hardware requires no station power. Only the air sampler requires battery power. The new collection techniques are designed to require approximately the same amount of time as the current environmental monitoring; approximately 240 minutes. Data is recorded on the archival bags and no biohazardous trash is created.
Operational ProtocolsPreflight surface and air samples are collected from all launch vehicles and ISS modules traveling to ISS. The samples collected are obtained by the investigation team. Air and surface samples are collected from a diverse range of locations in the vehicle or module at Launch minus 15 (L-15) or 15 to 20 days prior to hatch closure. A mixture of new locations and previously sampled locations are selected on a case-by-case basis determined by the investigator team. Collection of inflight air and surface samples from ISS occurs prior to every vehicle docking to ISS. Four air samples and twelve surface samples are collected during each collection session. Any surface condensation is collected, if available. The SWAB Return Kit containing in flight samples returns on each subsequent Space Shuttle flight. The time, humidity, and temperature of the ISS are monitored during the in-flight operations. Two water-samples (one hot and one ambient) are obtained every four weeks from the Potable Water Dispenser (PWD) in the U.S. Lab.
Results/More Information
Sample collection for the surface and air samples has been completed, and the samples have been returned to Earth for analysis. Water sampling will take place during future missions. (Evans et al. 2009)
Related Web Sites
Publications
Ground Based Results Publications
ISS Patent Publications
Related Publications
- Castro V A,Thrasher A N,Healy M ,Ott C M,Pierson D L,Microbial Charcterization during the Early Habitation of the International Space Station Microbial Ecology 2004 47 119-126
- Song B ,Leff L G,Identification and Characterization of Bacterial Isolates form the Mir Space Station Microbiological Research 2005 160 111-117
- Ott C M,Bruce R J,Pierson D L,Microbial Characterization of Free Floating Condensate Aboard the Mir Space Station Microbial Ecology 2004 47 133-136
Images
NASA Image: ISS010E11563 - An example of contamination that has developed on one of the interior panels aboard ISS. This image shows how contamination can form on interior ISS surfaces. Crews have weekly sessions to clean ISS surfaces. SWAB will help us understand the microbes involved in contamination and how to deal with them. + View Larger Image
The air sampling device used for the SWAB experiment, which collects air through a gelatin filter and can retain particles as small as viruses. Image courtesy of NASA. + View Larger Image
Dust mites collected on a previous human space flight. + View Larger Image
If updates are needed to the summary please contact JSC-ISS-Program-Science-Group. For other general questions regarding space station research and technology, please feel free to call our help line at 281-244-6187 or e-mail at JSC-ISS-Payloads-Helpline.