The trio of satellites orbiting Mars were able to estimate the thickness of its crust, how it's changed over time and determined that the planet's liquid outer core is made of molten rock, too. That bit of knowledge is the result of "analyzing the tides in the Martian crust and mantle caused by the gravitational pull of the sun and the two moons of Mars," according to Phys Org.

How'd this new map come to be? The Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter tracked the changes of gravity while they were in orbit (going over a mountain gives stronger gravitational pulls, valleys have a weaker one) over 16 years. Then, two years of analysis and computer models removed any variations in the imagery that weren't caused by gravity. Sadly no Prothean artifacts have been discovered. Yet.