The use of DASI in the ERAST/Pathfinder Science Project


Imaging interferometric data of the Hawaiian Islands will be acquired, processed and analyzed in conjunction with a flight test planned for summer 1997 by NASA's Environmental Research Aircraft & Sensor Technology (ERAST) program. A specially designed Digital Array Scanned Interferometer (DASI) will operate from the Pathfinder, a high-altitude remotely piloted aircraft (RPA). The DASI, which originated at Washington University and was jointly developed with Ames Research Center, will meet the stringent engineering and operating requirements of the RPA with respect to remote operation, very light weight, and low volume, power and bandwidth.

Pathfinder RPA

  • Ceiling: 70,000 ft
  • Duration: 14 hrs
  • Weight: 480 lbs
  • Payload: 25 lbs
  • Mfr: Aerovironment

DASI sensor

  • Spectral resolution: 150 cm-1
  • Signal-to-noise: 100:1 @ peak
  • Number effective bands: variable (>100)
  • Spectral range: 400-1000 nm
  • IFOV: 0.5 mr by 1.4 mr

Data Team:

A Data Team will generate DASI image data suitable in quality, format and timeliness for scientific analysis. The Team will produce for priority science targets a Level-1 product: a data cube containing at-sensor radiance per channel and per pixel, with associated metadata. Level-1 product generation will involve laboratory-based sensor calibration, in-flight sensor characterization and reduction of Level-0 (raw interferogram) data by application of a suite of software modules. The overflights will be supported by simultaneous ground-based measurement of atmospheric aerosols with a solar radiometer, and subsequent correction of Level-1 imagery for atmospheric effects.

Science Team:

DASI data of selected sites will be provided to a collaborating Science Team with established research sites on Kauai, surrounding waters and, by means of a conventional piloted aircraft, other Hawaiian Islands. The Team will include investigators from several research institutions, including a core group from Ames Research Center and the University of Hawaii. Science activities include investigation of the relationship between crop fertilizer inputs and nitrous oxide flux, identification and mapping of alien plant species, and evaluation of DASI sensitivity to plant canopy photosynthetic efficiency. Coastal zone science activity will assess the use of DASI data for detection and monitoring of algal bloom events related to nutrient enrichment or other environmental perturbations. Other Science Team Members have interests in mineralogy, volcanics, cloud properties, coral reef dieback and agroforestry applications.

References:

Philip D. Hammer, Lee F. Johnson, Anthony W. Strawa, Stephen E. Dunagan, Robert Higgins, James Brass, Robert E. Slye, Donald V. Sullivan, Brad M. Lobitz, William H. Smith, and David L. Peterson, "Surface Reflectance Mapping using Interferometric Spectral Imagery from a Remotely Piloted Aircraft", IEEE IGARSS 2000 (International Geoscience and Remote Sensing Symposium), July 24-28, 2000, Honolulu HI, Proceedings vol. 2, pp. 816-818. [Conference abstract, Poster]


For more information about the DASI instrument, please contact:
Philip D. Hammer
Ecosystem Science & Technology Branch
MS 242-4
NASA Ames Research Center
Moffett Field CA 94035-1000
(415) 604-3383
phammer@gaia.arc.nasa.gov

or

Stephen E. Dunagan
Ecosystem Science & Technology Branch
MS 207-1
NASA Ames Research Center
Moffett Field CA 94035-1000
(415) 604-4560
sdunagan@mail.arc.nasa.gov


For more information about the ERAST/Hawaii Science effort, please contact:
David L. Peterson
Ecosystem Science & Technology Branch
MS 245-4
NASA Ames Research Center
Moffett Field CA 94035-1000
(415) 604-5899
dpeterson@mail.arc.nasa.gov

or

Lee F. Johnson
Ecosystem Science & Technology Branch
MS 242-4
NASA Ames Research Center
Moffett Field CA 94035-1000
(415) 604-3331
ljohnson@mail.arc.nasa.gov


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