IAF-02-U.1.01 Earth Rings for Planetary Environment Control Jerome PEARSON, John OLDSON, and Eugene LEVIN Star Technology and Research, Inc. 53 rd International Astronautical Congress 10-19 Oct 2002/Houston, Texas, USA For permission to copy or republish, contact the International Astronautical Federation 3-5 Rue Mario-Nikis, 75015 Paris, France