Grades: 5 to 12

Comets are mysterious, distant travelers originating from the depths of our solar system and orbiting the sun in a highly elliptical path.  Star gazers see comets as specters with luminous tails arching across the night sky for a month or two, and then disappearing from sight.  Our ancestors considered comets to be Portents of evil.  Some comets never come back, with orbital periods of tens of thousands of years.  Others return more often, with periodic orbits of less than 200 years long.  For this reason, seeing comets like Halley’s Comet, with its seventy-six year orbit, is often a once in a lifetime experience.  Comets are scientifically valuable because they may be remnants of the material out of which the planets and moons formed.  Comets may even contain clues about early life on Earth.
 
Sometimes called “dirty snowballs” comets are small, irregularly shaped lumps of rock, dust, and ice.  They originate in either the Kuiper Belt, located outside Neptune’s and Pluto’s orbit, or in the Oort Cloud, hundreds of times farther away from Pluto extending halfway to the nearest star.  Gravitational disturbances can cause a comet to go hurling toward the Sun.  As a comet enters the inner solar system, heat from the Sun vaporizes the ice, forming an enormous cloud of gas and dust around the tiny comet.  The closer the comet gets to the Sun, the more gas and dust blow away forming a tail that stretches out millions of kilometers. As the comet travels away from the Sun to the outer reaches of the solar system, the tail shortens and the gas cloud disappears. 
 
Team members, working as scientist and engineers, become the astronauts and mission controllers on a daring exploration of comets in the not-too-distant future.  Rendezvous with Comet is similar to NASA’s Stardust program which launched in February 1999.  In December 2003, Stardust will rendezvous with comet Wild-2 and, bring back cometary material and gains from the newly discovered Interstellar Dust beam entering our solar system.
 
At the conclusion of this mission, the team will have successfully plotted a course and traveled to rendezvous with a comet.  They will have gained experience that will spark discussion about recent comet sightings and spur further scientific inquiry.