Dufek and his collaborators at the University of California-Berkeley received enough data to determine the size, depth and shape of the bomb sag.
The team propelled particles of varying materials (glass, rock and steel) at different speeds into dry, damp and saturated sand beds before comparing the divots with the bomb sag on Mars.
No matter the type of particle, the saturated beds consistently produced impact craters similar in shape to the Martian bomb sag.
That's a bomb sag," says rover lead scientist Steve Squyres.
The fact that it's a bomb sag says there was some kind of violent emplacement process, some kind of high-energy process," notes Squyres.
And, says Squyres, "if you saw a bomb sag like this on Earth, you would say those sediments were wet--like soft, deformable mud.