How "The Martian" used multispectral imaging technology from NASA

Images of Mars taken by NASA’s multispectral imaging camera called THEMIS—Thermal Emission Imaging system—were used in the recent blockbuster movie "The Martian."

Designed at Arizona State University (ASU), THEMIS is a multispectral imaging camera on NASA’s Mars Odyssey spacecraft that has a main task of mapping rock mineralogy and detecting heat, which yields information on the physical and thermal properties of the Martian surface. THEMIS consists of infrared and visible multispectral imagers that share the optics and housing, but have independent power and data interfaces to the spacecraft to provide system redundancy.

The system features a 320 x 240 element uncooled microbolometer array was declassified and produced commercially by the Raytheon Santa Barbara Research Center under license from Honeywell, Inc. The array is thermoelectrically-cooled to stabilize the focal plane array to ± 0.001 K. The imager has ten stripe filters that produce ten ∼1 μm-wide bands at nine separate wavelengths from 6.78 to 14.88 µm. Two filters cover the same spectral region centered at 6.78 µ to improve the detection of carbonate by improving the signal to noise ratio in this spectral region. The nine IR wavelengths include eight surface-sensing wavelengths and one atmospheric wavelength.

Additionally, THEMIS has a 1024 x 1024 Kodak KAI-1001 CCD image sensor with a 9 µm pixel size that uses a filter plate mounted directly over the area-array detector on the focal plane. On the plate are multiple narrow band filter strips, each covering the entire cross-track width of the detector, but only a fraction of the along-track portion of the detector. This sensor uses five color filters superimposed on the CCD sensor to acquire multispectral coverage. Band selection is accomplished by selecting reading out only part of the resulting frame for transmission to the spacecraft computer. The imager uses 5 stripes each 192 pixels in along-track extent. The entire detector is read out every 1.3 seconds and the five bands selected are centered near 425, 550, 650, 750, and 860 nm.

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