Larry J wrote:
A really long mission like PKE could possibly be shortened by a few years with ion propulsion. There would be some savings as a result of reduced Deep Space Network support over the mission as well as by not needing to maintain the mission operations team for so many years.

Alex writes:
Since New Horizons is based on the JHU/APL CONTOUR bus, it already incorporates "hibernation mode", which would substantially cut down on the amount of required active DSN tracking time, a very significant, if generally unknown, cost. I doubt very seriously whether the cost savings of shorter flight time, as well as the development costs of an ion propulsion solution for the outer planets, is more attractive than flying New Horizons, or any other Pluto Kuiper Belt mission, as is (i.e., with off-the-shelf technology). DS1's technology demonstration showed that long term ion propulsion for interplanetary spacecraft is very feasible; however, there are a whole host of other hurdles (e.g., power sources) that must be overcome to translate this into a viable option. Moreover, from my understanding from engineers involved in the PKB AO, these solutions, despite the current "hype", will probably not be cheap. In my opinion, frankly, if we can fly New Horizons for $500 million in 2006, then why wait a few years to fly a $750 million (the types of numbers I've seen presented) mission that arrives, maybe, a few years eariler?

Alex R. Blackwell
University of Hawaii