In this activity (on page 5 of PDF), learners use dry ice and household materials to make scientifically accurate models of comets. Learners will investigate the ingredients in comets and how comets could have contributed to water ice on the Moon that the Lunar Crater Observation and Sensing Satellite (LCROSS) Mission launched in 2009 is designed to detect. This activity can be used as a demonstration or groups of learners can make their own comets. Adult supervision is recommended. The PDF contains step-by-step instructions, photos, presentation tips, extensions and links to background information.