Phoenix Color Targets

Caption NASA:"These images of 3 Phoenix Color Targets were taken on Soles 1 and 2 by the Surface Stereo Imager (SSI) on board the Phoenix Lander. The bottom target was imaged in approximate color (SSI's red, green, and blue filters: 600, 530, and 480 nanometers), while the others were imaged with an infrared filter (750 nanometers).
All of them will be imaged many times over the mission to monitor the color calibration of the camera. The two at the top show grains 2 to 3 millimeters in size that were likely lifted to the Phoenix deck during landing. Each of the large color chips on each target contains a strong magnet to protect the interior material from Mars' Magnetic Dust".