Spacecraft: Surface Operations: Instruments

Calibration Targets

When you adjust the color on your television set, you do so by picking something on the screen that you know should be a certain color (such as grass should be green) and you adjust your set accordingly. This is a form of calibration. You used the color of the grass as a reference point. Instruments that go to Mars also need to be calibrated so that scientists receive accurate information. There has to be a known reference -- a calibration target.

The rover's calibration targets are objects with known properties. For example, the Mössbauer Spectrometer´s calibration target is a thin slab of rock that is rich in magnetite. The APXS also uses another reference point on the inside of its dust doors. When these doors are closed, they protect the APXS sensor head from martian dust and offer a calibration target on their interior surfaces. Mini-TES has an internal target located in the Pancam Mast Assembly as well as an external target on the deck of the rover.

The Pancam calibration target is, by far, the most unique the rover carries. It is in the shape of a sundial and is mounted on the rover deck. Pancam will image the sundial many times during the mission so that scientists can adjust the images they receive from Mars. They use the colored blocks in the corners of the sundial to calibrate the color in images of the martian landscape. Pictures of the shadows that are cast by the sundial's center post allow scientists to properly adjust the brightness of each Pancam image. Children provided artwork for the sides of the base of the sundial.