Abstract

Deep Impact collided with comet Tempel 1 excavating a crater controlled by gravity. The comet’s outer layer is composed of 1-100 mm fine particles with negligible strength (<65 Pa). Local gravitational field and average nucleus density (600 kg m-3) are estimated from ejecta fallback. Initial ejecta were hot (>1000 K). A large increase in organic material occurred during and after the event, with smaller changes in CO2 relative to H2O. On approach, the spacecraft observed frequent natural outbursts, a mean radius of 3.0±0.1 km, smooth and rough terrain, scarps, and impact craters. A thermal map indicates a surface in equilibrium with sunlight.