The Deepest Map: Charting the Mariana Trench
Somewhere in the western Pacific, the seafloor drops away.
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The Deepest Map: Charting the Mariana Trench
The Mariana Trench is about 11 kilometres deep — a depth that took humans 150 years, dozens of ships, and several generations of technology just to measure. This episode follows that story, from the first tentative soundings made by HMS Challenger in 1875, through the acoustic revolution of the 1920s, the dangerous descent of the bathyscaphe Trieste in 1960, and on into the robotic swath-mapping surveys that finally gave us something approaching a real picture of what is down there.
The science of depth measurement turns out to be quieter and stranger than you might expect. It's a story of waiting — for a rope to hit bottom, for an echo to return, for an autonomous robot to surface with its data card. And it is, in a small way, a story about the limits of knowledge: even today, the best measurements of Challenger Deep carry an uncertainty of several dozen metres, because sound itself changes speed as it descends into cold, high-pressure water. The trench is still, in some senses, being mapped.
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