JPL Electronic Nose (ENose) - 05.13.15

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
The JPL Electronic Nose (ENose) is a full-time, continuously operating event monitor designed to detect air contamination from spills and leaks in the crew habitat in the International Space Station. It fills the long-standing gap between onboard alarms and complex analytical instruments. ENose provides rapid, early identification and quantification of atmospheric changes caused by chemical species to which it has been trained. ENose can also be used to monitor cleanup processes after a leak or a spill.
Science Results for Everyone
The E-nose knows. Researchers verified that a prototype “electronic nose” could measure the condition of air in a closed environment. On three runs in different positions, temperatures recorded by the e-nose remained between 21-26°C and the relative humidity between 65 and 85 percent. The on-orbit prototype differs from the ground version of the instrument only in packaging and electronic circuit design, and the data indicate that its main functionality is preserved in microgravity. Design of an electronic nose for use in space presents electronic, mechanical, and chemical constraints, but the technology is now sufficiently mature for space applications.

The following content was provided by Margaret A. Ryan, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Margaret A. Ryan, Ph.D., Jet Propulsion Laboratory, Pasadena, CA, United States

Margie L. Homer, Ph.D., Jet Propulsion Laboratory, Pasadena, CA, United States

NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Information Pending

ISS Expedition Duration
October 2008 - October 2009

Expeditions Assigned

Previous ISS Missions
The ENose has been operated on ISS since Expedition 18.

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Experiment Description

Research Overview

  • Many air quality problems are known to have occurred on numerous International Space Station (ISS), MIR and Space Shuttle flights. In most of these events, the problem chemical(s) were either never identified or were identified only after the crew had been exposed to it. These represent health and safety risks to the crewmembers.

  • No instrument currently exists on board the ISS to detect and quantify chemical leaks or spills in real time; ENose is designed to help reduce risks associated with crewmember exposure to toxic or dangerous chemicals.

  • The JPL ENose atmospheric event monitor can provide rapid, early identification and quantification of target chemicals. Target chemical species for the ISS technology demonstration include leaks or spills of selected compounds such as organic solvents, freon, mercury, sulfur dioxide, and possibly marker chemicals which signal the beginnings of electrical fires. The JPL ENose can be also used to monitor cleanup processes after a spill or leak has occurred.

ISS Science Challenge Student Reflection

ISS Science Challenge Selected Project
This experiment was chosen because we were learning about healthy bodies. The ENose detects contaminated air so the air is safe. I thought the ENose was cool.
- Parker, Alex, Carissa, and Garett, Grade 5, North Tama Elementary School, Traer, Iowa

The JPL Electronic Nose (ENose) is an array-based sensing system which contains 32 conductometric sensors. The Second Generation ENose was trained to detect, identify and quantify 21 chemical species, the majority of which are organic solvents or commonly used organic compounds, which might be released through a leak or a spill in a spacecraft crew cabin. It was extensively ground-tested, and includes data analysis software which will identify and quantify the release of a target chemical within 40 minutes of detection.

Past ENose investigations have focused on organic compounds such as common solvents and a few selected inorganic compounds, ammonia, water and hydrazine. For the new ENose to be performed on the ISS, two inorganic species have now been added to the analyte set, mercury and sulfur dioxide. To accommodate these inorganic species, the sensor array will incorporate a hybrid sensor approach, including both new sensing materials and new sensing platforms made up of microhotplate sensor substrates. Materials approaches to these analytes have been determined using models of sensor-analyte response developed under this program. Predictive models will also be used to complement array training for additional software analyses including chemical family identification and identification of unknown analytes. Analysis of data taken by the sensor array will be included on the ENose control computer, and event analysis will be available within 40 minutes of event onset.

The ENose event monitor, by identifying and quantifying trained-for chemical species, fills the gap between an alarm (which provides no ID or quantification) and high-end analytical instruments. ENose has demonstrated a wide dynamic range, ranging from fractional ppm to 10,000 ppm. Its array based sensing mechanism means that it can be trained to detect new chemical species, and training data can be uplinked to add new species to its on-board data library. ENose runs continuously (30 to 360 data points/hr) and autonomously; it requires only minimal crew interaction and requires no consumables. The ENose is low mass (less than 4 kg), small volume (less than 4 liters) and low power (less than 20 W), in addition to being microgravity-insensitive, robust, and rugged. It is capable of analyzing volatile aerosols as well as vapors.

Future applications of the JPL ENose may also include environments other than the spacecraft crew cabin and similar enclosed environments. Such applications may include integration with larger devices such as analytical instruments, and with environmental monitoring and control systems.

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Space Applications
The JPL ENose is envisioned to be one part of a distributed system for automated monitoring and control of the breathing atmosphere in inhabited spacecraft in microgravity. It is designed as an event or incident monitor, capable of providing rapid, early identification and quantification of changes in the atmosphere caused by leaks or spills of compounds to which the device has been trained. The flexibility of the device includes the ability to be trained to new compounds, the possibility of providing sensor sets for particular analyte suites, and a wide dynamic range (fractional ppm to 10,000 ppm), making it a valuable part of an air quality monitoring and control system that is comprised of several types of instruments. Such a system can be included in an environmental control system which actuates remediation of anomalous events.

Earth Applications
Many important and diverse Earth-based applications exist for ENose technology. One major driver is the current need for advanced detection devices for security (both civilian and military) and health safety applications, such as the detection of explosives and infection monitoring.

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Operational Requirements
Upon arrival on board ISS, ENose will be unpacked from stowage and set up by a crewmember. ENose will be affixed to an EXPRESS Rack for power. ENose will run continuously for minimum of six months; data will be transferred to ground in Health and Status packets and in periodic file transfer. Data will also be archived in ENose until file transfer (up to 30 days). The crewmembers will perform periodic confirmational events to collect air samples in vicinity of ENose for analysis on ground.

Operational Protocols
ISS crewmembers will retrieve the ENose from stowage and install it on an EXPRESS Rack with a bracket assembly and/or Velcro; connect the power cable and the data cable. ENose will be powered on and the crewmember will verify the following: LED illumination; display operation; clear air inlet and outlets. ENose is autonomous with possible occasional crew commanding and periodic status checks (once or twice per month). Crewmembers will have periodic attended events if ENose detects a potential spill or leak. When ENose is relocated, the crewmember will need to reset the IP address.

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Results/More Information

Analysis of ENose monitoring data showed regular, periodic rise and fall of humidity. Occasional releases of Freon 218 (Perfluoropropane), used in ISS cooling systems, were detected by ENose and the Analyzing Interferometer for Ambient Air (ANITA) payload, another air quality monitoring instrument. Formaldehyde, which is not detectable by any other instrument in the U.S. Lab, was frequently detected by ENose at low concentrations and may result from off-gassing of polymeric seals or o-rings heated by operating equipment. Similarly, the presence of methanol was detected by ENose but could not be correlated to any specific activities aboard. ENose and ANITA detected the unexpected presence of sulfur hexafluoride (SF6). SF6 was not on the JPL ENose target list of compounds, so it was reported as an "unknown" event for the in-flight analysis. In postflight, based on sensor response modeling inputs and experimental verification, it was determined these unknown events could be related to SF6 (Shevade 2010). Each detected event lasted from 20 to 100 minutes, which is consistent with the air replacement time in the U.S. Lab (Ryan 2009, 2010a).

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Results Publications

    Shevade AV, Ryan MA, Homer ML, Kisor AK, Lara LM, Zhou H, Manatt KS, Gluck SE, Goddard, III WA, Blanco M.  Characterization of Unknown Events Observed by the Third Generation JPL Electronic Nose Using Sensor Response Models. 40th International Conference on Environmental Systems, Barcelona, Spain ; 2010 Jul 11-15

    Ryan MA, Manatt KS, Gluck SE, Shevade AV, Kisor AK, Zhou H, Lara LM, Homer ML.  The JPL Electronic Nose: Monitoring Air in the U.S. Lab on the International Space Station. 2010 IEEE Sensors, Kona, HI; 2010 Nov 1-4 1242-1247.

    Ryan MA, Manatt KS, Gluck SE, Shevade AV, Kisor AK, Zhou H, Lara LM, Homer ML.  Operation of Third Generation JPL Electronic Nose on the International Space Station. SAE International Journal of Aerospace. 2009; 2009-01-2522.

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Ground Based Results Publications

    Kateb B, Ryan MA, Homer ML, Lara LM, Yin Y, Higa K, Chen MY.  Sniffing out cancer using the JPL electronic nose: A pilot study of a novel approach to detection and differentiation of brain cancer. NeuroImage. 2009; 47(Supp 2): T5-T9. DOI: 10.1016/j.neuroimage.2009.04.015.

    Shevade AV, Ryan MA, Homer ML, Kisor AK, Manatt KS, Lara LM.  Monitoring Pre-Combustion Event Markers by Heating Electrical Wires . SAE International Journal of Aerospace. 2009; 2009-01-2543.

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ISS Patents

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Related Publications

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Related Websites
The Electronic Nose - An Environmental Sensor
NASA Press Release 08-299: NASA Plans Test of 'Electronic Nose' on International Space Station

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image The Third Generation ENose and the two subsystems that comprise it: the Sensor Unit (science core) and the Interface Unit (hardware and software connections to the ISS).
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image ENose baseline deployment option on board ISS. ENose is shown attached via a Velcro patch to an EXPRESS Rack face. Power and data cables connect the ENose to ISS EXPRESS (Expedite the Processing of Experiments to the Space Station) Rack power and Ethernet resources.
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image NASA Image: ISS018E011643 - View of the Electronic Nose (Enose) in US Laboratory Destiny during Expedition 18.
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