A space probe that makes intense observations of a planet, especially one that obtains data from the surface. Examples include the Mars Global Surveyor, which used processes such as altimetry and spectroscopy to map the planet Mars, and the Magellan probe that carried out detailed mapping of 99% of the surface of Venus using altimetry, radiometry, synthetic aperture radar (SAR), and other instruments. A planetary mapper is placed into a high-inclination orbit, such as a polar one, because the planet below rotates to reveal its entire surface.