PHOTO: 37-year-old Charlie Duke, the youngest astronaut to walk on the moon (April 21, 1972)
From our vantage point on Earth, the moon looks small. But if you were to hop in a spaceship, don a spacesuit, and go on an epic lunar hike, how long would it take to walk all the way around it?
The answer depends on many factors, including how fast you can go, how much time every day you spend walking, and what detours you’ll need to take to avoid dangerous topography. Such a trip around the moon could take longer than a year, but in reality, there are a lot more challenges to overcome.
According to NASA, a total of 12 humans have stepped foot on the lunar surface, all of whom were part of the Apollo missions between 1969 and 1972. The footage that was beamed back to Earth showed how challenging (and, apparently, fun) it was to walk or more accurately, bounce around in the moon’s low gravity, which is one-sixth the gravity of Earth.
Theoretically, walking the circumference of the moon could be done faster than previously predicted based on the steps of Neil Armstrong and Buzz Aldrin in their bulky moon suits. Just how practical would it be? “I think logistically, it could be done,” Aidan Cowley, a scientific adviser at the European Space Agency, told Live Science. “But it would be a very strange mission to support.”
One of the biggest challenges would be carrying supplies, such as water, food, and oxygen. “I don’t think you’d be carrying them in your backpack,” Cowley said. “Because that’d be far too much mass, even if you’re at one-sixth gravity.” Therefore, you would need to have a support vehicle with you. This vehicle could double as shelter.
“A lot of the agencies are looking into the concept of having a pressurized rover, which can actually support the astronauts when they’re doing exploration missions, kind of like portable mini-bases,” said Cowley. “You could use that to go in at night and resupply and then go back out during the day and walk around again.”
Moon adventurers would also need a spacesuit with a design that allows for optimal movement. Current spacesuits are still not created with excessive locomotion in mind. But NASA is working on more advanced spacesuits optimized for the lunar surface for the agency’s forthcoming Artemis program that aims to land astronauts on the moon by 2024. These form-fitting suits will be more lightweight and flexible, allowing for the arm swing necessary to walk properly on the moon.
Walking around the moon poses a number of different dangers. The moon’s harsh topography would make finding a suitable route around it quite tricky, especially with meteor craters that can be several miles deep. You would also have to factor in light and temperature when planning the route.
“At the equator [of the moon], and during the day, you’re looking at temperatures at around 100 degrees centigrade [212 degrees Fahrenheit],” Cowley said. “And then at nighttime, it drops to like minus 180 C [minus 292 F].” The lunar cycle also means there are days when there is little or no sunlight, and at least half the journey would have to be done in the dark.
Providing protection against these extreme temperatures could be possible with specially designed suits and the rover for protection. But the fluctuating temperatures could also change the state of regolith – the fine gray soil that covers the moon’s solid bedrock – and affect how fast you could walk on it.
Radiation could pose an even greater danger. Unlike Earth, the moon does not have a magnetic field that helps deflect radiation from reaching its surface. “If there was no major solar activity at a time, then it may not be so bad,” said Cowley. “But if there was a solar flare or coronal ejection and you’re hit by high levels of radiation, that could make you very, very sick.”
This type of mission would also require a huge amount of endurance training because of the demands of exercising in low gravity on your muscles and cardiovascular system. “You’d have to send an astronaut with ultra-marathon-level fitness to do it,” Cowley said. Even then, walking at a top speed would be possible only for around three to four hours a day.
So, if a person is walking at 3.1 mph (5 km/h) for 4 hours a day, then it would take an estimated 547 days, or nearly 1.5 years to walk the moon’s circumference, assuming their route isn’t too disrupted by craters and you can deal with the temperature changes and radiation.
Humans won’t have the technology or equipment to accomplish such a feat until at least the late 2030s or early 2040s. “You’d never get an agency to support anything like this,” said Cowley. “But if some crazy billionaire wants to try it, maybe they can pull it off.”