Comet, Saturn probes on schedule

Two highly anticipated outer-space collisions went into action Thursday. On schedule, NASA launched its Deep Impact rocket toward a comet called Tempel 1. The rocket will launch a copper-coated projectile into the comet's surface. Ideally, the dust cloud and crater created by the collision will beam information to a nearby companion spacecraft about the comet's chemical makeup. Comets are some of the oldest objects in the universe, but there is limited information about their internal chemistry.

Meanwhile, the Huygens probe is set to land on the surface of atmosphere of Titan, a moon of Saturn, on Friday, according to the European Space Agency. Titan has a thick atmosphere, unusual for satellites in our solar system. The probe, which travels at 14,000 miles per hour, separated from its rocket Dec. 25.