The Multi-angle Imaging SpectroRadiometer (MISR) was launched into polar orbit aboard NASA's Terra spacecraft on December 18, 1999. Testing began even before the instrument cover opened. The 1000-line image at left, corresponding to about 41 seconds of "dark current" data, was acquired on 12 February 2000, during orbit 821. The image at right shows the same data, but with the contrast greatly enhanced. Random fluctuations in the camera video signal produce the "salt and pepper" appearance, and the faint horizontal banding is due to random fluctuations in the video background level. The brightness of all these fluctuations is less than 0.3% above the average background level with the camera cover closed, a minuscule amount compared to the signal produced when Earth light illuminates the cameras.
