Why have satellite altimetry systems proven inadequate for fine-scale bathymetric seafloor mapping?

The abyssal plains, spanning more than half of the Earth's total crustal surface, remain less systematically mapped than the surfaces of the Moon or Mars. Deep ocean bathymetry was historically hindered by the attenuation of electromagnetic signals in water, which limits satellite altimetry to low-resolution approximations. In recent years, high-endurance autonomous underwater vehicles (AUVs) equipped with multi-beam swath bathymetry systems and synthetic aperture sonars have revolutionized oceanic cartography. Navigating untethered along pre-programmed trajectory grids hundreds of meters above the seafloor, AUVs record sub-meter bathymetric topography, identify manganese nodule distributions, and detect sub-seafloor hydrothermal circulation with unprecedented accuracy.

Answer and explanation

Correct answer: A. Electromagnetic radiation attenuates rapidly when passing through water.

  1. Step 1: Scan the passage for why satellite altimetry is limited when mapping the deep ocean seafloor.
  2. Step 2: The second sentence states: "Deep ocean bathymetry was historically hindered by the attenuation of electromagnetic signals in water, which limits satellite altimetry to low-resolution approximations."
Answer
Electromagnetic radiation attenuates rapidly when passing through water.

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