New sonar tool is a ‘game changer’ for mapping the seafloor

Amazing stuff! Terra incognita! What lurks beneath!

"An emerging sonar technology that scans the seafloor at centimeter-scale resolution is dazzling researchers with its potential. Commercial synthetic aperture sonar (SAS) devices, originally developed by the military to identify explosive mines, are now being deployed by scientists ...

Only a Rhode Island–size patch of the world’s deep-sea floors has been observed up close, according to a study ... That imaged area is likely to grow with the adoption of SAS, which can efficiently reveal fine details in wide swaths of the sea floor, unmasking its biology and geology. ...

SAS is analogous to the synthetic aperture radar (SAR) systems on satellites that are increasingly being used to map Earth’s surface. In SAR, a moving beam source focuses multiple “pings” on a single point on Earth’s surface. The radar reflections are stitched together to create a picture equivalent to one taken by a much larger aperture antenna. SAS does the same thing with sound instead of radio waves. ..."

From the abstract:

"Despite the importance of visual observation in the ocean, we have imaged a minuscule fraction of the deep seafloor. Sixty-six percent of the entire planet is deep ocean (≥200 m), and our data show that we have visually observed less than 0.001%, a total area approximately a tenth of the size of Belgium. Data gathered from approximately 44,000 deep-sea dives indicate that we have also seen an incredibly biased sample.

Sixty-five percent of all in situ visual seafloor observations in our dataset were within 200 nm of only three countries: the United States, Japan, and New Zealand. Ninety-seven percent of all dives we compiled have been conducted by just five countries: the United States, Japan, New Zealand, France, and Germany. This small and biased sample is problematic when attempting to characterize, understand, and manage a global ocean."

New sonar tool is a ‘game changer’ for mapping the sea floor | Science | AAAS "Devices that mimic giant acoustic cameras can spy animal burrows, explosive mines, and metallic deposits"

How little we’ve seen: A visual coverage estimate of the deep seafloor (open access, this article is not really related to SAS)

A shipwreck off the coast of Nantucket in Massachusetts was imaged with synthetic aperture sonar.