A test target (for spacecraft) is a common feature on interplanetary landing craft such as the
Viking Lander and
Mars Exploration Rovers.
The target is usually a visible marker or plate on the exterior of the vehicle within sight of the lander's imaging system (usually a
CCD camera). The target possesses samples of
primary colors
A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a bro ...
and a
grey scale. The camera uses this much like a photographer would use a
chip chart on Earth; the color samples allow the camera to compensate for
white balance and
contrast. The target provides a visual reference as well, so that the initial
orientation
Orientation may refer to:
Positioning in physical space
* Map orientation, the relationship between directions on a map and compass directions
* Orientation (housing), the position of a building with respect to the sun, a concept in building de ...
of the camera can be fixed.
On the Mars Exploration Rover, the target was designed with a pillar elevated above the main surface, so that it could be used as a
sundial
A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat ...
.
Spacecraft components
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