Altimeter
An altimeter was an instrument used to measure the altitude to a fixed level. A RADAR altimeter made this determination by measuring the distance between the craft in flight and ground directly below it.

In 2254, the Talosians scanned the library computer banks of the , including a diagram of the US Ranger 5 space probe. Among the equipment noted on the schematic was the probe's RADAR altimeter. ()

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Sensor technology