There are many remarkable things about the planet, Mars. One that keeps getting my attention is the amazing “grand canyon” known as, “Valles Marineris”. This trench that stretches across the Mars surface is roughly the length of the American continent and about 6 miles deep. It raps around the surface of the planet with a roughly circular valley system at each end.

How did such a feature come about on the cold lifeless frozen planet? One theory suggests that it’s the result of the contraction of the planet as a whole due to the cooling of the planet’s core. So, why is there only one such feature on the planet? Why not many if the planet’s surface is covered with a rather uniform outer crust as on Earth?

Looking at the feature from above, Valles Marineris reminds me of something i’ve seen before. Like a BB or a pellet fired at a tomato or some sort of soft fruit. It penetrates the skin and travels just beneath the surface forcing the meat away from it bulging the surface as it blasts along inside the fruit and if it travels close enough to the surface the skin will rupture and split open leaving a gaping wound. Finally, the projectile exits thru the skin and continues on its way. Immediately the entrance and exit areas are filled back in with pulp leaving a circular distubance at the entrance and exit points.

Pulp and meat from the insides of the fruit have been ejected from the rupture region between the entrance and exit marks. But, the memory in the fruit’s outer skin will pull the rupture’s open tear back together and the liquified pulp inside will flow into the wound partially filling the remaining gap.

The Valles Marineris on Mars is more then vaguely similar to such a wound on a piece of fruit. It is rather precisely the same! If you have an air rifle handy, you can try this experiment for yourself. Get a nice ripe tomato or a soft apple. Put it at a safe distance and using basic shooting safety precautions, shoot at any edge of the fruit. You will need to hit the edge just far enough in to cause the skin to rupture as the BB, or pellet passes through the fruit.

Planets like Mars likely have a soft molten region below the outer crust. Could a huge asteroid or comet (perhaps 100 miles in diameter) have enough momentum and mass to penetrate the Mars outer crust, travel 1500 miles thru the molten interior and exit the crust to continue on its way? Perhaps badly mishappen and deformed, but nonetheless basically intact?

I suspect this is the story this huge gash on the surface of Mars is telling us. If so, think of the other impacts such an event would have on a planet. Would it be able to sustain life afterwords? Would the planet’s rotation on its axis be changed in ways, or its orbit shift any around the Sun?

What do you think caused the Valles Marineris?

Wayne Hollyoak