A radar aboard ESA’s Mars Express detected an extraordinarily bright reflection beneath 1.5 kilometres of Martian polar ice, spread across a patch roughly 20 kilometres wide. Years later, a second radar aboard NASA’s Mars Reconnaissance Orbiter finally reached the same layer — and saw only a faint echo, deepening a debate over whether there is liquid water, unusual rock, or something else beneath Mars’s south pole.

MARSIS found an intensely bright boundary beneath Mars's south polar ice. SHARAD has now reached the same layer and returned a much fainter signal. The post A radar aboard ESA’s Mars Express detected an extraordinarily bright reflection ben…

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1. SpaceDaily 18 Aug
   A radar aboard ESA’s Mars Express detected an extraordinarily bright reflection beneath 1.5 kilometres of Martian polar ice, spread across a patch roughly 20 kilometres wide. Years later, a second radar aboard NASA’s Mars Reconnaissance Orbiter finally reached the same layer — and saw only a faint echo, deepening a debate over whether there is liquid water, unusual rock, or something else beneath Mars’s south pole. ↗