During June and July 2007, engineers from HyVista Corporation and Integrated Spectronics made a number of modifications to a HyMap sensor that enabled it to operate at altitudes up to 50,000 ft in an unpressurised configuration.
Modifications included a re-working of the operational firmware, new solid state recording media, installation of heating mats and thermal insulation and the partial pressurization of the liquid nitrogen dewars that house infrared detector arrays.
A series of engineering test flights were conducted in early August in one of NASA’s WB-57 aircraft. Imagery was collected from 50,000 ft around the Houston area and in New Mexico.
The HyMap had previously flown in the WB-57 during the CARTA II deployment to Costa Rica in early 2005. However, typical flight altitudes for that deployment were around 25,000 – 30,000 ft. Proposed large area mapping projects required operation at higher altitudes.
At 50,000 ft, the HyMap has a 30m pixel size and a swath width of 18 km. At typical flight speeds of the WB-57, the HyMap can image around 6300 sq km per hour.
Aside from being used for efficient, large area spectral mapping projects, this configuration of the HyMap also generates imagery that can be used to simulate data from proposed future hyperspectral satellites.
The test flight imagery demonstrated that the signal to noise ratio, spectral and radiometric stability and the overall image quality were not degraded by the high altitude operations.