Something that not everyone thinks about when envisioning life on the ISS, that being smelling dangerous chemicals. NASA astronauts on space shuttle Endeavour's STS-126 mission will install an instrument that can "smell" dangerous chemicals in the air. Designed to help protect crew members' health and safety, the experimental "ENose" will monitor the space station's environment for harmful chemicals such as ammonia, mercury, methanol and formaldehyde. The ENose Sensor Unit (the darker-looking metal object), housed in its Interface Unit (white). The ruler, shown for size comparison, is 12 inches (about 30.5 cm) long. (Photo on right)

The ENose fills the long-standing gap between onboard alarms and complex analytical instruments. Air-quality problems have occurred before on the International Space Station, space shuttle and Russian Space Station Mir. In most cases, the chemicals were identified only after the crew had been exposed to them, if at all. The ENose, which will run continuously and autonomously, is the first instrument on the station that will detect and quantify chemical leaks or spills as they happen.  

"The ENose is a 'first-responder' that will alert crew members of possible contaminants in the air and also analyze and quantify targeted changes in the cabin environment," said Margaret A. Ryan, the principal investigator of the ENose project at NASA's Jet Propulsion Laboratory, or JPL, in Pasadena, California. JPL built and manages the device.  

Specifically, the shoebox-sized ENose contains an array of 32 sensors that can identify and quantify several organic and inorganic chemicals, including organic solvents and marker chemicals that signal the start of electrical fires. The ENose sensors are polymer films that change their electrical conductivity in response to different chemicals. The pattern of the sensor array's response depends on the particular chemical types present in the air.

The instrument can analyze volatile aerosols and vapors, help monitor cleanup of chemical spills or leaks, and enable more intensive chemical analysis by collecting raw data and streaming it to a computer at JPL's ENose laboratory. The instrument has a wide range of chemical sensitivity, from fractional parts per million to 10,000 parts per million. For all of its capabilities, the ENose weighs less than nine pounds and requires only 20 watts of power.

This will be the ENose's second trip into space. An earlier version flew with John Glenn on the STS-95 Space Shuttle in 1998. Since that time, the ENose has increased in sensitivity and reduced in size. The current, third-generation ENose, including its Interface Unit, is about the width and length of a shoe box, and about half as high. The Interface Unit contains 2 computers, one to manage the instrument's operation and data acquisition, and one to analyze the data, and connects the ENose to the ISS EXPRESS Rack, through which it will transfer data to the support team on Earth. (Photo on left)

Station crew member will unpack the ENose on December 9 to begin the instrument's six-month demonstration in the crew cabin. If the experiment is successful, the ENose might be used in future space missions as part of an automated system to monitor and control astronauts' in-space environments.  

The ENose is now in its third generation. The first ENose was tested during a six-day demonstration on the STS-95 shuttle mission in 1998. That prototype could detect 10 compounds, but could not analyze data immediately. The second-generation ENose could detect, identify and quantify 21 different chemicals. It was extensively ground-tested. The third-generation ENose includes data-analysis software to identify and quantify the release of chemicals within 40 minutes of detection. While it will look for 10 chemical types in this six-month experiment, the new ENose can be trained to detect many others.