So How Do You Weigh Things In Zero-Gravity?

With extremely controlled and strict diets, it's not like astronauts have to worry about gaining too much weight on the space station. But have you ever stopped and wondered how you would actually measure mass in a weightless environment? After all, the entire concept of weight and scales is entirely dependent on gravity.

It turns out you can, you just need a stand-in for the constant force that keeps us all glued to the ground when we're on Earth. And as astronaut Don Pettit demonstrates, a low-tension spring fills that void when gravity isn't strong enough to be felt. But measuring the mass of an object this way isn't as easy as just looking at a number on a scale. In this instance, you need to measure the object's oscillations over time as it swings back and forth and fights against the spring. The faster it moves, the lighter an object is — and with proper calibration and calculations, you should be able to accurately determine if it's time to lay off that freeze-dried astronaut ice cream. [YouTube]


    Accellerate it to a set speed and crash it into a device that measures force.


        ...or just measure the force you used to accelerate it to that speed in the first place.

          ... exactly... spelled correctly :)

      How does that make sense? Firstly, how do you measure the acceleration and speed of the object accurately? It is much easier to time a regular oscillation than an object moving in a straight line. Secondly, once it is at a set speed, the force with which it "crashes" into something has nothing to do with the initial acceleration, it is a measure of momentum and time (both of which are hard to measure accurately for a crash) as well as a bunch of other unknowns related to the stiffness of the material.

    Spin it around at a set speed and measure the centrifugal force, wack that in a formula...

      *centripetal. And circular motion isn't mass dependant.

        No but it applies a known acceleration to an unknown mass, the result of which can be measured. m=f/a problem solved.

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