Satellite image quality depends on the equipment available and the aiming decisions executed at control centers. The resolution of photography varies among platforms. The best nonmilitary satellites offer very good imagery: Quickbird can resolve objects as small as 0.6 m across, while Ikonos offers images with a resolution of 1 m per pixel (4 m per pixel for multispectral images). Older spacecraft, such as the French SPOT, offer resolution of 10 m per pixel, while Landsat can resolve objects 30 m across.
The resolution of military reconnaissance satellites is classified, but civilian experts, such as those at the Federation of American Scientists, have opined that 10 cm per pixel would not be unrealistic. In addition, these satellites' sensors can also take pictures in a night sky. Access to such data is restricted; however, if human intelligence ("humint'') suggested that some kind of incident would occur, governmental public health and/or law enforcement could seek access to these "birds.''
Photographs of use in detecting stricken people or animals are most likely taken using optical cameras, infrared sensors, and perhaps radar antennas using synthetic-aperture techniques, assuming that a high enough resolution is achieved.
The data are available in real-time and reliable. Degree of coverage depends on how many satellites of a particular type are available to cover the area being monitored at any given time. Temporary gaps in coverage have been known to occur when malfunctioning satellites, or those reaching the end of their useful lives, have not been replaced in time.
When an imaging customer (government or commercial user) wants to study something of interest, a satellite specialist can recommend what type(s) of imaging would be best and, therefore, which "birds'' would be most useful. After the satellite has taken photos, the analyst interprets the photos and may recommend additional views of the target in question, or perhaps other sites. It may be desirable to tilt the camera to do such tasks as photograph the side of a building or other geographic feature rather than the top of it. Satellites are equipped with maneuvering thrusters allowing their controllers to adjust their orbits and quickly bring their cameras to bear on scenes of interest; the camera's angle is adjustable, which allows the camera to change from an overhead view to an oblique view. Should an image taken provoke curiosity or concern, the satellite's operator can maneuver it to pay special attention to the location where the image was taken. The interpretation center will process and enhance the images retrieved from satellites by using sophisticated software.
Unfortunately, this software cannot interpret the images for us. Image analysts are highly skilled professionals that the government calls upon to detect a developing catastrophe before it harms us; they are in very short supply.
Was this article helpful?