CAPE CANAVERAL, Fla.—NASA is blaming unusually soft rock for last week’s sampling fiasco on Mars.
The Perseverance rover came up empty after attempting to collect its first core sample on the red planet for eventual return to Earth. Data beamed back last Friday showed that the rover drilled to the proper depth of nearly 3 inches (8 centimeters), and pictures of the borehole looked good. But it quickly became clear the sample tube was empty.
