The New York launch came a fortnight after the Fitbit Force was unveiled - a rival activity tracker that includes a height-measuring altimeter that can record how many stairs its owner has climbed.
The altimeter system, measuring the time it takes light pulses to travel to a reflecting object and back to the satellite, will calculate the precise elevations and positions of ice sheets, icebergs, clouds and land formations.
However, as I began testing the $99 Fitbit Ultra, a slightly upgraded version that adds a stopwatch and altimeter for measuring stair climbs, I began to warm to the device's charms.
The radio altimeter measures the distance of an aircraft above the ground rather than above sea level.
Using the TOPEX dual-frequency (Ku- and C-band) radar altimeter measured nadir total electron contents (TECs) from an orbital altitude of 1354 km, the fidelity of the IRI95 ionosphere model and GPS-derived Global Ionosphere Map (GIM) have been evaluated.
Micro-watershed elevation was measured using an altimeter.
The two main types are the pressure altimeter, or aneroid barometer, which approximates altitude above sea level by measuring atmospheric pressure, and the radio altimeter, which measures absolute altitude (distance above land or water) based on the time required for a radio wave signal to travel from an airplane, a weather balloon, or a spacecraft to the ground and back.
"Along with a number of students, I have spent many a fine afternoon standing on Manhattan's large, glacially scratched outcrops, wherever we could find them, measuring the elevation with a barometric altimeter and their position with a GPS device".
A more common form of radio altimeter, better suited for measuring rate of change of altitude, transmits waves continuously and derives the height from the phase difference between the transmitted signal and that reflected from the ground.
The ExoMars rover will use the same computer as Schiaparelli, the same radar altimeter to measure its height above the ground, and the same inertial measurement unit, which monitors acceleration and tracks the lander's position on its planned trajectory.
Two corrugated diaphragms sealed at their edges to form a capsule, which is evacuated, are used in aneroid barometers to measure atmospheric pressure (see altimeter).
