NEAR-EARTH COMETS
The comet Wilson-Harrington (also known as 1979 VA) passes very close to the Earth's orbit every 4.2 years. Scientists now estimate that it could contain a cubic kilometer of ice (Huebner, 1990, References). George Wetherill of the Carnegie Institute has predicted that up to 40 percent of near Earth objects (NEOs) are "water objects" (dormant or spent comets) (Wetherill, 1991, References). So a large fraction of the NEOs that we think of as dry asteroids are actually comet cores rich with ice and volatiles. Dr. Zuppero has done a study on comets as a source of ice. For additional general information (with pictures!) about comets, click here.
