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Experiment/Payload Overview

Brief Summary

Smoke and Aerosol Measurement Experiment (SAME) measures smoke properties, or particle size distribution, of typical particles from spacecraft fire smokes to provide data to support requirements for smoke detection in space and identify ways to improve smoke detectors on future spacecraft.

Principal Investigator

David L. Urban, Ph.D., Glenn Research Center, Cleveland, OH, United States

Co-Investigator(s)/Collaborator(s)

George Mulholland, , University of Maryland, College Park, College Park, MD, United States

Jiann Yang, , National Institute for Standards and Technology, Gaithersburg, MD, United States

Thomas Cleary, , National Institute of Standards and Technology, Gaithersburg, MD, United States

Zeng-guang Yuan, , National Center for Space Exploration Research, Cleveland, OH, United States

Payload Developer
Information Pending

Sponsoring Space Agency

National Aeronautics and Space Administration (NASA)

Sponsoring Organization:

Human Exploration and Operations Missions Directorate (HEOMD)

ISS Expedition Duration:

April 2007 - September 2010

Expeditions Assigned

15, 23/24

Previous ISS Missions

SAME is the successor to the Comparative Soot Diagnostics (CSD) experiment that flew aboard STS-75 in 1996. The experiment showed that smoke produced in low gravity is different from smoke produced in normal gravity (microgravity smoke particles are larger).

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Experiment/Payload Description

Research Summary

• Fire is commonly detected by measuring changes in the amount of airborne microscopic particles (one of the components of smoke).
  
  
• Smoke detectors currently in use on ISS and Space Shuttle are based on detectors used on Earth that detect different sizes of smoke particles.
  
  
• SAME will measure the distribution of particle sizes in smoke from on-orbit combustion of several materials found in the spacecraft. Testing will also examine the effects of sample temperature, air flow and smoke residence time (near the source) on the particle size distribution of the smoke.
  
  
• Results will allow an evaluation of the performance in microgravity of the two existing U.S. spacecraft smoke detector designs, in use on the Shuttle and ISS, and evaluate other fire detection devices.
  
  
• Information from this experiment will improve the design requirements for and reliability of smoke detectors on future spacecraft.

Description

Spacecraft smoke detectors must detect different types of smoke. For example, hydrocarbon fuels typically produce soot and plastics produce droplets of recondensed polymer fragments. While paper and silicone rubber produce smoke comprised of liquid droplets of recondensed pyrolysis products. Each of these materials produces a different type of smoke, with particles of various sizes and properties.

Smoke and Aerosol Measurement Experiment (SAME) will assess the size and distribution of smoke particles produced by different types of material found on spacecraft such as, Teflon, Kapton, cellulose and silicone rubber. SAME will evaluate the performance of the ionization smoke detectors (used on Space Shuttles), evaluate the performance of the photoelectric smoke detectors (used on the ISS) and collect data for which a numerical formula can be developed and used to predict smoke droplet growth and to evaluate alternative smoke detection devices on future spacecraft.

The experimental design and practical application of the data will be complemented by the development of a numerical code to predict the smoke droplet growth as a function of the fuel pyrolysis rate, the thermodynamic properties of pyrolysis vapor, and the flow environment. SAME also has the capability to evaluate other fire detection/particulate sensing devices for the test materials. The results will provide statistics of the smoke particulate size distribution for a range of smoke generation conditions and measurement of a readily modeled reference for validation of smoke growth models.

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Applications

Space Applications

The SAME experiment will provide technology for an advanced fire detector for future spacecraft that will be used for long duration missions. SAME will provide quantitative data on the sensitivity of these detectors to reduced gravity smokes that will allow evaluation of the adequacy of these existing technologies using relevant data. The current Fire Prevention, Detection, and Suppression (FPDS) program plan allows for the re-evaluation of future sensor technology, to allow new technology and capability to be utilized. The results from SAME are needed to provide the reduced gravity baseline data against which future detection technology developments can be evaluated.

Earth Applications

The smoke detectors developed from the results of SAME can also be useful in other extreme environments on Earth, such as submarines or underwater laboratories. Accurate detection of smoke in these environments can save lives.

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Operations

Operational Requirements

For SAME the crew will pyrolyze (decompose the material by extreme heat) basic spacecraft materials (Kapton, Silicon Rubber, Teflon and cellulose (lamp wick)) and a baseline material (Dibutyl Phthalates) in the MSG. There will be a total of twenty test points (each sample will be tested four times) . Each carousel (sample holder) can hold up to six samples. If time permits additional test points can be completed with the samples in the carousel.

After pyrolysis, the smoke is aged in a chamber to simulate the time it takes the smoke to build up and move to the detectors. Smoke, the product of the pyrolysis is characterized in the following ways:

• Smoke before and after the aging is trapped on a transmission electron microscopy grid, located inside Thermal Precipitator Module, for study on the ground.
  
  
• Smoke after aging is run through the P-Trak to determine the number of particles per unit volume.
  
  
• Smoke after aging is run through the DustTrak to determine the mass concentration of the particles.
  
  
• Smoke after aging is run through a modified home ionization smoke detector (First Alert) to determine the diameter concentration of the particles.
  
  
• The smoke is then run through the ISS and Shuttle smoke detectors that are parts of SAME in the MSG to test their response to the smoke that has been characterized.

Operational Protocols

SAME will use probes to heat a wire and drive the smoke onto a small collection grid (approximately 1/8 in. diameter) as it flows past using an effect know as thermophoresis (what causes dust to stick to the wall behind a radiator). At each test point, two samples of the smoke will be taken: the first within seconds of its generation and the second after a defined aging period, during which the size and shape of the smoke particulates will have changed. These sample grids will be returned to Earth from the ISS and examined under a transmission electron microscope.

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Results/More Information

Building from the earlier DAFT experiment that successfully tested a particulate detector, SAME tested the size of smoke aerosols of spacecraft materials, like Kapton and teflon.

Smoke particulate produced in low-gravity by SAME was found to be typically 50% larger in count mean diameter than similar conditions in normal gravity. The particle sizes were all below 300-nm suggesting that discriminating smoke from spacecraft dust possibly could be achieved by detecting in the sub-micrometer range (Urban et al. 2008). These results have significant implications for the design of smoke detection systems for current and future spacecraft.

The experiment also modeled the smoke transport in the US Laboratory using ECLSS data. Numerical modeling of smoke transport predicted that actual detection times can be quite long and strongly dependent on detector location and inside geometry of obstructions that block cabin air flow (Urban et al. 2008). (Evans et al. 2009)

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Related Web Sites

Microgravity Combustion Science

ISS Research Project-SAME

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Publications

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Ground Based Results Publications

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ISS Patent Publications

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Related Publications

• Urban David L.,Griffin DeVon ,Ruff Gary ,Cleary Thomas ,Yang Jiann ,Mulholland George ,Yuan Zeng-guang ,Detection of Smoke from Microgravity Fires Proceedings of the International Conference on Environmental Systems 2005 2005-01-2930

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Images

A candle flame in Earth's gravity (left) and microgravity (right) showing that difference in the processes of combustion in microgravity. Image courtesy of NASA, Johnson Space Center.

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The Smoke and Aerosol Measurement Experiment (SAME) hardware located in the Microgravity Science Glovebox (MSG). Image courtesy of NASA, Johnson Space Center.

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NASA Image - ISS015E26265: View of Smoke and Aerosol Measurement Experiment (SAME) hardware in the Microgravity Science Glovebox (MSG) in the U.S. Laboratory/Destiny. SAME aims to test the performance of ionization smoke detectors and evaluate the performance of the photoelectric smoke detectors.

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NASA Image - ISS015E27408: Expedition 15 Flight Engineer, Astronaut Clay Anderson examines the sample carousel configuration during the Smoke and Aerosol Measurement Experiment (SAME) hardware set up on board ISS.

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NASA Image - ISS015E27410: Astronaut Clay Anderson is seen here installing the sample carousel into Smoke and Aerosol Measurement Experiment (SAME) hardware located in the Microgravity Science Glovebox (MSG) in the U.S. Laboratory/Destiny.

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NASA Image - ISS015E27423: NASA astronaut Clay Anderson, Expedition 15 flight engineer, is seen here working on the Smoke and Aerosol Measurement Experiment (SAME) hardware located in the Microgravity Science Glovebox (MSG) in the Destiny laboratory of the International Space Station. SAME will measure the smoke properties, or particle size distribution, of typical particles that are produced from different materials that can be found onboard station and other spacecrafts.

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