This NASA website dispels the myth that there is no gravity in an orbiting spacecraft. It includes the classic diagram of a cannon fired from a mountaintop that gives a projectile various velocities and shows the various orbits that result. The site explains how a drop tower is not an "anti-gravity device."
NASA Glenn Research Center. What is Microgravity?. Cleveland: NASA Glenn Research Center, March 17, 2006. http://www.nasa.gov/centers/glenn/shuttlestation/station/microgex.html (accessed 20 January 2017).
%0 Electronic Source %D March 17, 2006 %T What is Microgravity? %I NASA Glenn Research Center %V 2017 %N 20 January 2017 %8 March 17, 2006 %9 text/html %U http://www.nasa.gov/centers/glenn/shuttlestation/station/microgex.html
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