yaron@utastro.UUCP (Yaron P Sheffer) (11/19/86)
***** Instead of favoring one mission or another (Pluto orbiter vs. TAU), how about sending that TAU spacecraft equipped with a small probe which would be deployed a few AU before Pluto's orbit, and then it will go into orbit around that "planet"? I like having the cake and eating it too. ***** You have noticed my wording "planet". I always have found the non-standard origin of Pluto very satisfying in explaining its peculiar orbit, i.e., Pluto is not a major planet to Sun, but a body which has suffered a close encounter with the Neptunian system. The fact that there is a current commensurability with Neptune is not a proof against such an encounter: Otherwise, a pendulum at rest is a proof that it has never been swinging! And as already been mentioned, having a moon orbiting Pluto doesn't make it a standard major planet either: it could well be a tidally induced breakup. Remember that no other REAL major planet in this solar system is even close to Pluto regarding the moon/planet mass ratio. And now for something (completely) different.... shooting the solar system. Of course any spacebuff would love to have a postcard from Voyager showing this SS from afar. But: 1) As it stands now, no Voyager has ever ventured outside of the SS. Many years will pass before this will happen (even with Pluto's orbit as a definition here of the solar system's "edge"). Hence, while still being inside some planetary orbits, any such picture is a technical headache, because of the need to cover so many steradians. Also, planets will be seen as points of light at the best resolution --- and a major problem in figuring out the required exposure times for each. It could also happen that some are already too faint to shoot. And of course: one thing JPL engineers would be happy to avoid, is directing their craft's cameras towards Sun itself. Maybe after many years, when it becomes apparently fainter.... 2) Same with Pluto, resolution-wise: Since the Voyagers' resolution element is 4 seconds of arc, and that planet substends 0.1 arcsecond at Earth, these craft must come at least as close as 1 AU to Pluto before anything is resolved. I am convinced that no Voyager is planned to pass that close to Pluto. However, from 10 AU or less, it would be possible to resolve that "planet" into two points of light: Pluto and Charon. But, indeed, we are doing it already from here, using speckle interferometry. And if major mistakes are detected in my remarks, I will be more than happy to learn about them! Y. Sheffer Astronomy Dept, U. of Texas, Austin, TX 78712.