Determining altitude by atmospheric pressure actually gives a result more like depth (determined from the pressure exerted by the atmosphere dependent on its density which depends on the amount of atmosphere above given the composition of the atmosphere in question), so the increasing "altimeter" might very well actually read in thousands of feet toward the surface from, say, 1 Pa of pressure. Of course, calibrating such a thing would require a known, homogenous composition for the atmosphere in question. http://en.wikipedia.org/wiki/Altimeter and reasoning makes it quite clear that calibration of barometric altimeters requires a variety of constants based on the planet's size, atmospheric composition, location on the planet, and temperature. It might be more rational to assume it's DRADIS based, utilizing the "Range"/"Distance" (from the acronym's expansion) to the planet from its DRADIS contact information. --CalculatinAvatar 01:41, 28 December 2005 (EST)