= Microgravity
<Microgravity> is a condition of very small residual acceleration or apparent weight experienced within an experimental system. An orbiting <spacecraft> and its freely moving contents fall together under <gravity>, greatly reducing the support forces experienced on the ground. A <drop tower> provides a shorter interval using the same <free fall> principle.<Zero Gravity Research Facility by NASA>[Free-fall microgravity and experimental facility]{ref}
Residual disturbances include <air resistance>, vibrations, vehicle manoeuvres and spatial variation in gravitational acceleration. Their importance depends on the experiment's duration and length scale. Suppressing gravity-driven convection or settling lets <surface tension>, diffusion and other processes become easier to isolate; the result is an experimentally controlled change in dominant forces, rather than removal of the gravitational field.
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