investigator. Exposing a comet's core is no easy task. Not only are comets relatively small - Tempel 1, for example is believed to be about five to nine miles (8 to 14 km) long and about one-third that in diameter - they are moving very quickly. Deep Impact, for example, will have to blast across space at 6.2 miles (10 km) per second to overtake comet Temple 1, drop off a stubby-nosed, copper-capped projectile in its path and scramble to a safe distance to observe the mega-explosion. The comet is expected to strike the coffee-table sized projectile with the force of 4.5 tons of dynamite, scientists said. Complicating the orbital ballet are several unknowns, including the exact size of the comet, its slow tumble and the fact that its interior could be as loosely structured as a bowl of cornflakes or packed as tightly as concrete on a sidewalk. --More 2321 Local Time 2021 GMT
