Science

How long would it take for an astronaut to walk around the moon?

During the Apollo missions, 12 astronauts were lucky enough to be able to walk on the Moon. However, on each sortie, the teams traveled only a short distance on the lunar surface around their module, deploying deflectors and collecting rock samples. If an astronaut really wanted to walk around the moon, how long would it take?

The answer depends on a multitude of factors, including how fast you can move, how much time you walk each day, and what detours you take to avoid dangerous topography. Such a trip around the Moon could take over a year, but in reality there are many more challenges to overcome.

A total of 12 humans set foot on the lunar surface, and all participated in the Apollo missions between 1969 and 1972. The images that were sent back to Earth showed how difficult it was to walk – or more precisely to bounce back. – in the weak gravity of the Moon, which is one sixth of that gravity of the Earth. However, NASA research has since suggested that it is possible for humans to maneuver the Moon much faster than Apollo astronauts.

Theoretically, traveling the circumference of the Moon could be done faster than expected. During the Apollo missions, astronauts bounced off the surface at an average speed of 2.2 km / h, according to NASA. This slow speed was mainly due to their pressurized and awkward space suits which were not designed for mobility. If the astronauts had worn more ergonomic suits, they certainly would have picked up the pace.

Improve the suits to increase the walking speed of the astronauts

In 2014, a NASA study published in the journal Journal of Experimental Biology tested how fast humans could walk and run in simulated lunar gravity. To do this, the team asked eight participants (including three astronauts) to use a treadmill aboard a DC-9 aircraft, which performed special parabolic trajectories on Earth to simulate gravity on the Moon during 20 seconds for each dish.

The lack of ergonomics of the space suits worn by the astronauts of the Apollo missions prevented them from making too large pendulum movements to move more quickly. © NASA

This experiment revealed that participants were able to walk up to 5 km / h before starting to run. This is not only more than double the walking speed shown by the Apollo astronauts, but also quite close to the average maximum walking speed of 7.2 km / h on Earth, according to the researchers. The participants achieved these rapid speeds because they were able to swing their arms freely, much like humans run on Earth.

This pendulum movement created a downward force, which partially compensated for a lack of gravity. One of the reasons the Apollo astronauts were so slow on the lunar surface was that they couldn’t do it properly because of their big suits. At this new hypothetical maximum speed, it would take approximately 91 days to travel the 10,921 km of the Moon’s circumference.

For context, it would take about 334 days of non-stop walking (that is, without stopping to sleep or eat) to complete the 40,075 km circumference of the Earth at this speed, although it be impossible to do because of the oceans. Obviously, it is not possible to walk nonstop for 91 days, so circling the Moon would take much longer.

Topography, temperatures and physical condition: multiple constraints

Planning your route is also extremely important. Carrying food, water and oxygen is necessary for survival. And it wouldn’t fit in a backpack. A support vehicle, such as a rover, would then be another necessity to think about. In addition, the topography of the Moon is extremely chaotic (some craters being deep), avoiding these areas would also be a priority for any traveler.

moon temperature variations atmosphere
The temperature variations on the Moon can be very large, going from an extremely hot environment to a freezing one. © B. Hermalyn

Light and temperature should also be taken into account when planning the route. At the equator, and during the day, it is temperatures of around 100 ° C that must be faced. And at night, the temperature drops to -180 ° C. The lunar cycle also means that there are days when there is little or no Sun, and at least half of the trip should be done in the dark. Temperatures could also change the state of the regolith and thus affect walking speed.

This type of mission would also require a huge amount of endurance training due to the demands of low gravity exercise on the muscles and cardiovascular system. A level of high competition marathon runner would be required according to the ESA. Even then, walking at maximum speed would only be possible for about three to four hours a day. So, if a person walked at 35 km / h for 4 hours a day, it would take about 547 days, or almost 1.5 years, to travel around the circumference of the Moon, assuming the route is not too disrupted.

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