TAU, Pluto, and This Solar System
Yaron P Sheffer
*****
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.
Robert DeMarco
Could some one tell me how far an AU
is?
An Ex-megawarser should know, but I
dont
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[ UUCP: ncoast!robertd ]
[ Ex-megawars name: MAXFLIGHT ]
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wy...@cfa.uucp
> Could some one tell me how far an AU
> is?
>
earth to the sun, about 93 million miles.
--
Bill UUCP: {seismo|ihnp4}!harvard!talcott!cfa!wyatt
Wyatt ARPA: wy...@cfa.harvard.edu