The image has been captured by the Mars orbiter, Odyssey. It has been orbiting Mars since 2001 and takes thousands of images of the Martian surface, every month.
The Mars Odyssey orbiter is equipped with a heat-vision camera also called the Thermal Emission Imaging System (THEMIS). THEMIS can detect changes in surface temperature while it circles the red planet every seven hours. How much heat is detected by TEHMIS depends on the texture and minerals of the moon too.