The coral reefs of Bikini Atoll can be mapped by a NASA satellite’s green laser, which penetrates up to 40 meters underwater.
By Paul VoosenLate in 2018, just after its arrival in orbit, NASA’s ICESat-2 satellite passed over an iconic site from the atomic age.
By chance, its laser altimeter, used mostly to measure the changing height of polar ice, bounced light off the exposed rocks of Bikini Atoll in the South Pacific Ocean, home to 23 nuclear weapons tests.
Then, mission scientists looked closer: To their surprise, the laser was also generating underwater reflections. “We were not just seeing the atoll,” recalls Adrian Borsa, a geodesist at the Scripps Institution of Oceanography. “We were seeing this huge reef system underneath it.”Spark
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