Environmental issue
In his 1997 report, Katnik noted that the 1997 mission, STS-87, was the first to use a new method of ``foaming'' the tanks, one designed to address NASA's goal of using environmentally friendly products. The shift came as the U.S. Environmental Protection Agency was ordering many industries to phase out the use of Freon, an aerosol propellant linked to ozone depletion and global warming.
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