Algal bloom in Lake Erie photographed on September 5, 2006. The algal bloom shown covers several square kilometers.
In just 8 months, members of the Great Lakes Environmental Aerial Monitoring (GLEAM) mission--consisting of a multidisciplinary team of researchers, scientists, engineers, and technicians from the NASA Glenn Research Center, the National Oceanic and Atmospheric Administration (NOAA), and the Ohio Aerospace Institute (OAI)--designed, developed, integrated, and flight tested a highly specialized suite of instruments for the aerial measurement of water quality. During 2006, these instruments obtained spectral data of a sediment-laden river plume in Lake Michigan and an algal bloom in Lake Erie (shown in the preceding photograph). The suite of instruments consists of a Glenn-designed point spectrometer, a Glenn-designed hyperspectral imager, a commercial-off-the-shelf Global Positioning System (GPS) receiver, a commercial-off-the-shelf three-axis gyroscopic-stabilized inclinometer, and a Glenn-designed data-acquisition system (see the next photograph).
Glenn-designed water quality sensor suite mounted on the T-34 aircraft.
The custom hyperspectral imager obtains wavelength-resolved images of a lake in narrow 2-nm-wide bands of light (see the sketch). The hyperspectral imager wavelength range is approximately 400 to 900 nm, thus approximately 250 distinct spectral band two-dimensional slices of data constitute a single three-dimensional image cube as shown in the sketch. The point spectrometer significantly adds to the capability of the instrument suite because it can provide highly accurate measurements of the incident solar spectrum as well as of the atmospheric water vapor content. This combined sensor suite will allow for more accurate spectral radiometric measurements of lake constituents, allowing researchers to detect lower concentrations of pollutants or of harmful algal blooms.
Hyperspectral image “cube” data set obtained using the Glenn-built hyperspectral imager. The lower image is actual data from a slice of a near-infrared spectral band centered at 723 nm that correlates with a spectral feature in chlorophyll. At this wavelength, the contrast of an algal bloom in Lake Erie on September 5,2006, is significantly enhanced in comparison to conventional imaging techniques. The large area of white in the middle is a cloud, and the rest of the white is the algal bloom.
The entire suite of instruments weighs less than 2.3 kg and uses less than 15 W of power. This allows the package to be deployed on many types of aircraft. For example, the team was able to mount the instrument on the avionics door of a T-34 aircraft to obtain the desired data in a very cost effective manner (see the following photograph). This instrumentation suite demonstrates Glenn’s ability to deliver custom-designed flight-capable optoelectronic instrumentation and hardware for Earth science and space missions in a short amount of time.
Team that developed and deployed the instrument suite along with the instrument mounted on the side of the T-34 aircraft.
Find out more about this research:
Glenn’s Optical Instrumentation & NDE Branch:
http://www.grc.nasa.gov/WWW/OptInstr/
Glenn’s Combustion Branch:
http://www.grc.nasa.gov/WWW/combustion/
Glenn’s combustion diagnostics research:
http://www.grc.nasa.gov/WWW/combustion/zDiag.htm
Glenn contacts:
John Lekki, 216-433-5650, John.D.Lekki@nasa.gov,
Dr. Quang-Viet Nguyen, 216-433-3574, Quang-Viet.Nguyen-1@nasa.gov
Authors:
John D. Lekki and Dr. Quang-Viet Nguyen
Programs/projects:
Independent Research and Development
Last updated: December 14, 2007
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