Europa May Not Be As Smooth As It Looks

In terms of overall elevation change, no body in the solar system has less than Europa. No feature extends more than a few hundred feet above "sea" level. You've probably heard the saying that if you made a billiard ball Europa sized, it would have more elevation change. All that is true, but just because Europa is flat doesn't mean it's smooth. As a matter of fact, much of the equatorial region could consist of thin ice towers that would wreak havoc on any space probe attempting to land.

These towers, called penitentes, form through sublimation in cold, dry environments at tropical latitudes. We have them on Earth, where they are especially common in the Chilean Andes. Here, they are about 5-15 feet tall, but on Europa, where it could hardly be colder or drier, they could be 50 feet tall and each peak would be about 25 feet apart.

So, what do we do about this? Well, the solution is quite obvious -- don't land at the equator. We'll just have to hope the most interesting stuff isn't there. Luckily, it's going to be quite a long time before we attempt a landing on Europa, so we have time to sort this out.