The Moon may be much less dense and brighter than scientists once thought, according to observations made by the joint Defense Department-NASA mission Clementine. In fact, there is likely much more space between the dusty particles that make up the Moon's fragile surface than scientists thought. About 95% of the surface is not occupied or about 5% is actually particulate in nature, according to Bonnie J. Buratti, of the Jet Propulsion Laboratory in Pasadena, Calif., who reported the finding last week at AGU's Fall Meeting in San Francisco. Before the mission, scientists generally believed that the surface was more compact, or closer to about 85% unoccupied. But Clementine has changed this perception. The Clementine mission also enabled scientists to view the Moon when it is fully illuminated, which is not possible from ground-based observations because the Earth itself interferes with the path of light from the Sun to the Moon.