Off Planet Hikes: The Backpacker’s Guide to the Solar System

Grab a spacesuit and a few months of provisions. We’re taking you on a tour of the Interplanetary Parks Service.

The Ringed Planet rises over the strange ridge of its moon Iapetus in this still from a computer-animated film released by NASA's Cassini team. (Credit: NASA) Space is harsh. From damaging radiation to deadly gases and drastic temperature changes, pretty much any environment beyond Earth can kill you at a moment’s notice. Yet our cosmic backyard boasts natural wonders that rival the greatest found on terra firma. And, one day, when we have the technology for deep-space rocket launches, suitable protective gear, enough provisions to last the average hiker — and any number of X factors — lucky adventurers may get to hike these solar system monuments. It’s a far-future vision, a sort of Interplanetary Parks Service, where an extraterrestrial great outdoors beckons you toward adventure.

Pluto's moon Charon and its awe-inspiring Serenity Chasm. (Credit: NASA/Lunar and Planetary Institute) Travel to Pluto’s moon Charon and one feature really sticks out: Serenity Chasma, a 620-mile (1,000 kilometer) long canyon stretching across the surface. It reaches depths of 5.6 miles (9 km), an abyss far greater than the just-over-a-mile-deep Grand Canyon National Park in Arizona. Consider Serenity Chasma the grandest canyon any hiker could traverse, and with the proper provisions, the hike of a lifetime that would take months to complete in its entirety. But hey, it’s less than one-third the length of the Appalachian Trail.

(Credit: NASA/JHUAPL/SwRI) How, exactly, did such a big feature form? Charon was probably once an ocean world like Europa and Enceladus, fellow outer solar system moons circling Jupiter and Saturn. But over time, Charon's internal heat died down, freezing the ocean below the ice. That process would have forced the moon to bulge out in certain areas. And its surface, which may once have been a relatively smooth ice shell, cracked as the water expanded, like a soda can left in the freezer. That expansion left a giant scar across the surface of the world.

Four massive volcanoes make up the Tharsis Bulge on Mars. The largest of the four, Olympus Mons, is at bottom right. It's larger than France. (Credit: ESA/DLR/FU Berlin/Justin Cowart)

On Mars, one peak towers tall over all others: Olympus Mons. It's the highest mountain on any planet in the solar system* with a summit stretching 13.6 miles (20 km) high, or 2.5 Mount Everests. But while Everest is an endeavor to climb, rising dramatically high up into the sky, Olympus Mons rises up gradually, roughly five degrees at a time. That means that you could ascend one of the mightiest mountains in the solar system with only moderate hiking skills. While it takes multiple small hauls to acclimate to Everest’s thin air, there’s already no air on Mars, so you’ll already be carrying your own oxygen. And Olympus Mons is huge — about the size of France — a suitable brag to counter anyone's Everest stories. * Rheasilvia, a mountain on the asteroid Vesta, is 14 miles (22 km) high.

NASA's Lunar Orbiter 2 caught this image of the Marius Hills as it circled the moon in 1966. (Credit: NASA/Lunar and Planetary Institute) If Apollo 15 hadn’t landed at Hadley Ridge, and had instead chosen the alternate moon landing site in the Marius Hills, humans may have already hiked our next destination. The Marius Hills sit within Oceanus Procellarum, the largest of the lunar “seas.” Here, as the name implies, a series of small hills dot the landscape, creating the perfect playground for a series of day hikes, and ancient volcanic rocks aplenty for amateur geologists.

A hole in the moon could make the perfect lunar home. (Credit: NASA) And while the regions’ ridges would make for interesting exploration, the real selling point are the volcanic tubes. At least one — now known simply as the Marius Hills Hole — is nearly 300 feet deep, making it a potential hub for human habitation. Just imagine: you hike the hills by day, potentially exploring shallow canyons nearby. At night, you return to your camping lodge, a pressurized outpost protected from the harsh radiation of space. A 200-foot dome at the top of the ancient lava-formed feature stares back at Earth and the stars. Not only is the area home to some of the best hiking in the solar system — it might also be the perfect place for some rest and relaxation.

Ceres', a dwarf planet and the solar system's largest asteroid, boasts a truly unique mountain. Astronomers call it "Ahuna Mons." (Credit: Dawn Mission, NASA, JPL-Caltech, UCLA, MPS/DLR/IDA) Mountains are plentiful on Venus, Mars and Earth. It makes sense. Each of these planets has a rich geological history — the kind that gives rise to volcanoes and mountains and more. So, there are multiple choices of mountain hikes on these three planets. But on a dwarf planet called Ceres, the largest asteroid in the asteroid belt, there’s one — and only one — choice. Meet Ahuna Mons. It’s about 2.5 miles (4 km) high, and stretches about 12 miles (20 km) wide. It was likely formed when frozen mud pushed its way to the surface of Ceres, piling up into a high mountain made of salt, water ice, clay and other minerals. All this happened only a few hundred million years ago, making it also one of the newest hiking options beyond Earth. Just imagine: Thanks to gravity just a fraction of Earth’s and the gradual slope of Ahuna Mons, you could scale the only mountain of an ancient protoplanet, staring from its highest point at the dust-encrusted surface of what was once an ocean world.

The Ringed Planet rises over the strange ridge of its moon Iapetus in this still from a computer-animated film released by NASA's Cassini team. (Credit: NASA) Many intrepid hikers want to explore America’s Continental Divide, the area in the Rocky Mountains (and several other mountain ranges) where our continent buckles, leaving beautiful terrain in its wake. It’s a gateway to the Western United States. But North America's Continental Divide has nothing on the equatorial ridge of Iapetus, which divides an entire world for an 800 mile (1,300 km) stretch, encompassing three-quarters of the equator. If you started at one end, you’d make the gradual climb up one the ridge’s edge, eventually scaling to heights of 12 miles (20 km). In some areas, a thick gunk dominates your view — probably thrown off from Phoebe, a nearby moon that rains material onto the surface of Iapetus. But when you glance skyward toward Saturn, you’ll get a view that other large moons in the system just can’t match — Saturn’s glimmering rings. Go ahead, snap a picture or three. Maybe even a selfie.

(Credit: NASA/JPL-Caltech/Space Science Institute) So what made this unusual formation? Hypotheses vary, but at least one suggests that it could be from the collapse of a brief series of sub-satellites (that’s right, moon-moons) that fell back along the equator of Iapetus, creating the giant ridge seen today. Another idea is that it may have also formed thanks to an early rapid rotation rate that threw it out of a round shape. It could have even been formed by a similar process of ice buckling as on Charon. In any case, your reward for this hike is 800 miles of striking ring views from a rare vantage point — enough to make anyone dream of going to space.