Title: Once and future Pluto: what we know now, what the puzzles are, 
       and what we can learn from future observations and the 
       Pluto-Kuiper Belt mission. 



Leslie Young
Southwest Research Institute


Abstract:
 
Over the last decade, our broad understanding of the Pluto-Charon
system has been refined by continued modeling and more sensitive
observations from ground-based observatories and HST.  Despite this
refinement--or perhaps because of it--major puzzles remain.  How
was Charon formed?  How are methane and carbon dioxide ices 
distributed on Pluto's surface?  How will Pluto's atmosphere
and surface change as Pluto recedes from the Sun?  

I will review the observations and models that lead to our current
understanding of the orbits, interiors, surfaces, and atmospheres of
Pluto and Charon, highlighting the more pressing and confounding
questions.  I will finish with a description of the New Horizons
mission to Pluto-Charon and the Kuiper belt, discussing how this
mission will address our outstanding questions and revolutionize our
view of the edge of our solar system.