Turns out, the 1976 Viking lander on mars was only 3.5" from hitting ice. How much does that suck?

As part of its science program, the Lander dug a trench about 6 inches deep. The new model predicts that if it had gone an extra 3.5 inches — a bit longer than a credit card — it would have hit ice....

It goes to show that sometimes scientific discoveries can come down to a few inches and some luck, even on the surface of a planet hundreds of millions miles away.