Gravity affects many properties of the polymer while it is being made.
As early as 1984, it was suggested that these effects could be eliminated or at least reduced if the polymer were made in the low gravity of space. A joint NASA and industry program to study polymers made in low gravity was approved in January 1987 by the NASA Office of Commercial Programs with Paragon Vision Sciences of Mesa, Arizona, a leading manufacturer of polymers for contact lenses, as the Industrial Guest Investigator. The experimental protocol entails the polymerization of several monomer mixtures on orbit and comparison of the resulting materials with those obtained from a ground-control experiment. These experiments must be done in space because several days are needed for the polymers to form. The first experiment was carried out on STS-57 in July 1993.