Helgi Björnsson; Clifford, Stephen Mark, 1952-; Paige, David A.; Thorsteinn Thorsteinsson, 1960-; https://orcid.org/0000-0002-8680-1997; https://orcid.org/0000-0001-5362-1474; https://orcid.org/0000-0003-0771-1713 (Lunar and Planetary Institute, 2000)