The Moon has about 1/6th of Earth's gravity, which (it is said) would perhaps lead to muscle degeneration for humans living there long-term. However, what if those humans wore bodysuits weighted to increase their weight 6 times? Would that make walking (not jumping) on the Moon similar to walking on Earth? Would it exercise the muscles as much, or would the reduced Moon gravity still mean that muscles didn't get the right amount of exercise?


It's complicated! Keep in mind the distinction between weight and mass. On the moon, weight is 1/6 what it is on Earth, but mass is the same.

When you hold your arm straight out, you have to exert force equivalent to its weight to hold it in place. So on the moon, that force is much reduced.

When you move your arm, you have to exert force proportional to its mass to accelerate it, then more force proportional to its mass to stop it. On the moon, that force is unchanged!

So consider adding 5 times your mass in a bodysuit.

This would make "just standing around" on the moon feel somewhat more like it does on Earth, because the weight supported by your skeleton and musculature would be your Earth-standard weight, but it would make moving vastly, vastly harder, because you'd have to accelerate and decelerate 6 times your normal mass whenever you moved a limb.

So to get an equivalent amount of muscular exercise, you'd need somewhere between 0 and 5 times your weight in that bodysuit, depending on how active you were. The weight distribution likely wouldn't match your natural weight distribution, either, so moving would definitely be awkward.

One other thing such a body suit might be useful for would be to slightly compress you to increase your blood pressure, in order to force your heart to work a little harder to circulate blood. Otherwise, your heart musculature would likely atrophy over long periods of time.

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    $\begingroup$ In SF they also use centrifuges. $\endgroup$ Dec 15 '14 at 20:06
  • $\begingroup$ What about a suit designed to provide resistance to movement? Granted, it would be easier to just exercise, but going for a walk in a resistance suit would probably be more interesting. $\endgroup$ Dec 16 '14 at 1:44
  • $\begingroup$ @MarkyMark I might be missing something, but that doesn't make much sense to me. Resistance to what type of movement exactly? $\endgroup$
    – user
    Dec 16 '14 at 10:50

The straight answer is no. It has to do with the gravitational pull of the Moon and the parabolic paths of a mass in motion around it. First, think of dropping a textbook and a penny on the earth. Both fall with an acceleration of 9.8 m/s^2. On the Moon that acceleration would be 1.625 m/s^2. The thing is, that acceleration does not depend on the mass of the object, as the textbook/penny experiment demonstrates. As you walk, your center of mass rises and falls, and your walk is affected by the gravitational acceleration. It would always be awkward no matter how much mass you had stacked on your body.


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