QUOTE (SigurRosFan @ Feb 28 2006, 10:38 AM)
Is any definitive KBO selected for New Horizons, yet?
Alan Stern or John Spencer may correct or expand on this, but here's how I answered that question for the February 6 Planetary Radio
: "Once New Horizons passes Pluto, it will have only a very limited ability to change its course, which means that it can only study Kuiper belt objects that happen to lie within a roughly one-degree cone around its path. Unfortunately, none of the more famous Kuiper belt objects, including 2003 UB313, Quaoar, Chaos, Ixion, or Varuna, will lie within that cone. The mission planners do want to visit a reasonably large object, bigger than 50 kilometers in diameter, and hope to find one that has a different color from Pluto so may represent a different kind of evolutionary history. But no Kuiper belt object has yet been identified that fits the mission's criteria.
There are several excellent reasons for the New Horizons planners to delay their choice of Kuiper belt targets. First of all, which bodies would be in reach of New Horizons depended to a great extent on the spacecraft's launch date. But the most important reason is that the Kuiper belt objects that New Horizons will study have very likely not been discovered yet. Only about a thousand of them are now recognized and tracked. In fact, very few are known to lie in orbits near New Horizons' path, because New Horizons happens to be headed toward the galactic center. Astronomers have avoided searching for objects there because the density of the star field in that part of the sky makes it challenging to find them. But several new observatories and experiments are being developed that will multiply number of known objects by a factor of ten or more by the time New Horizons arrives at Pluto. For example, the Pan-STARRS observatory under construction by the University of Hawaii is a wide-field imager that will come online in 2009. It is estimated that Pan-STARRS could discover twenty thousand Kuiper belt objects over its operational lifetime, giving New Horizons lots of options."
In other words, I expect it'll be a while