Ski season is almost here! It's time to dust off your skis, grab your poles and prepare the main engine thrusters for blast-off, because this is no ordinary ski trip we're talking about. Think farther away than Whistler, much bigger than Aspen and way more remote than the peaks of the Himalayas—let's go skiing on the moon!
It's not as crazy as it sounds—in fact, skiing may turn out to be one of the best ways to get around on our natural satellite (the moon). One of the last people to land on the moon, Dr Harrison Schmitt, developed a gliding technique for getting around the powdery lunar landscape, which was inspired by cross-country skiing. Schmitt, who visited the Earth's orbital companion in 1972 with NASA's Apollo 17 mission, discovered that gliding allowed him to move faster and use less energy than the lunar bunny-hop (see below) that we're used to seeing in pictures and videos from the moon.
The science of movement is all about forces and energy. Walking depends a lot on the force of gravity. When we walk, we put our bodies off balance, essentially 'falling' forwards a little, then allow our legs to swing forward like a pendulum to 'catch' us.
On the moon, with only 1/6 the gravity of earth, objects fall, pendulums swing and astronauts walk much more slowly. Running presents a slightly different problem—instead of relying mainly on gravity to propel us, we use our leg muscles to provide the force by pushing hard against the ground. Some of that push gets us moving forwards but most of it goes into counter-acting gravity to keep us vertical. Our legs and feet have evolved for running in Earth's familiar gravity, but on the moon they provide considerably more upward force than we need—sending us soaring high above the surface in an inefficient waste of energy. On the other hand, the gliding motion of cross-country skiing allows our legs (and our arms, if we use poles) to direct more of our force in a horizontal direction without relying on the ups and downs of conventional terrestrial locomotion. Skis have two added benefits: their large surface area spreads out our weight to keep us from sinking into soft surfaces (usually snow, but also moon dust), and their long, straight shape provides stability and balance to make up for the clunky and awkward movement of a space suit.
Lunar skiing is not without its challenges. The moon dust (called lunar regolith) is a lot harsher than snow. Imagine glass shards and iron filings ground into a fine powder and you'll have a pretty good picture of what moon dust is made of. Your trusty fibreglass Rossignols aren't quite up for that job, but fear not, this is just the kind of problem that space exploration agencies are great at solving. In pursuit of finding cheaper, faster, more efficient and safer ways to explore the cosmos, NASA has come up with an incredible list of inventions—materials, machines and methods for overcoming the engineering challenges of worlds beyond our own.
And lunar skiing may not just be for those few, noble explorers made from the right stuff. Although no earthling has made the trip to the moon since Schmitt's mission in 1972, the first private tourist trip to lunar orbit is planned to launch in 2017 (tickets on sale now). Schmitt himself even envisions a far-future orbital alpine resort where thrill-seeking lunar tourists and pioneers can take to the slopes of the majestic Taurus-Littrow Valley, near the site of the Apollo 17 landing. Until that day, we’ll have to settle for slaloming on snowy slopes while we dream of carving down a crater. One final benefit of skiing on the moon: the jumps will be out of this world!