In many science fiction films over the past few decades that deal with humans on Mars, such as “Red Planet”, “Mission To Mars”, and the soon to be released “The Martian”, dust storms on Mars are always a pivotal and horrifying plot elements. On the screen, we see them destroying vehicles, antenna arrays, even whole buildings. Certainly, from Earth, these storms look scary. Small ones occur often, and sometimes they grow to engulf the entire planet. But according to scientists from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the makers of these science fiction films aren’t getting the science quite right.
"Every year there are some moderately big dust storms that pop up on Mars,” says Michael Smith, a planetary scientist at Goddard, “and they cover continent-sized areas and last for weeks at a time. Once every three Mars years (about 5 ½ Earth years), on average, normal storms grow into planet-encircling dust storms, and we usually call those 'global dust storms' to distinguish them.” But when it comes to the idea that these storms could lift vehicles up in the air and destroy buildings, not to mention scrapping a mission and stranding an astronaut on Mars, as happens in “The Martain”, there are a couple of factors that film makers aren’t taking into account.
One is wind speed. Even at their highest, wind speeds during Martian dust storms top out at around 60 miles per hour. That’s certainly a stiff breeze, but it’s not enough to destroy equipment. Even here on Earth, 60 miles an hour is less than half the speed of some hurricane-force winds.
Another factor is wind on Mars and Wind on Earth are two totally different phenomena. Why? As William Farrell, no, not the actor, this William Farrell is a plasma physicist who studies atmospheric breakdown in Mars dust storms at Goddard, explains, "The key difference between Earth and Mars is that Mars' atmospheric pressure is a lot less. So things get blown, but it's not with the same intensity.”
As is so often the case, the real science here is a bit more complex that the science that’s portrayed in science fiction. Martian dust storms do present a real threat to exploration of Mars, but it’s not from the dust sand-blasting its way through a space suit or from the wind tossing a habitat in the air. The big problem is the Martian dust itself. It’s not like dust here on Earth that would just get blown away by a light breeze. Martian dust particles are small and slightly electrostatic, so whatever they get on they stick to.
"If you've seen pictures of Curiosity after driving,” Smith says, “it's just filthy. The dust coats everything and it's gritty; it gets into mechanical things that move, like gears.” Not to mention the fact that when solar panels are coated with this dust they produce much less electricity. If they’re coated with enough dust they don’t produce any electricity at all.
Andrew J. Dunlop lives and writes in a little town near Boston. He's interested in space, the Earth, and the way that humans and other species live on it.
