starship-design: Re: Mystery force tugs

[rmarlin@network-one.com (Gene & James Marlin)]

> I gave you the link,so the author can discribe it better than I can.
> Since I can't READ the paper on the IR solution I wish not to >comment
> on it,

Anderson's original publication is in the Oct 5 98 Physical Review Letters.
Other physicists (like Katz of Washington University, St. Louis)
point out that radiation pressure from the RTGs on those craft are perfectly
adequate to account for the pressure (noted in S&T, Jan. 1999). Anderson
himself believes the error is internal to the spacecraft, and *not* a
problem with physics, pointing out that Earth and Mars do not display a
similar solar force but the relatively nearbly Ulysses spacecraft does,
therefore, whatever it is is specific to the spacecraft.

And no, Ben, there is no "url" you can go to to find the above, you'll just
have to use
a library.

The actual acceleration itself is constant at about 8.5exp-8 cm/s^2; the
very fact that it is constant is inconsistent with the increasing distance
to the Sun for Pioneer 10 and 11 between 1998 and the point it was first
detected in 1980 would indicate that it is not a force related to Sun, but
only a consequence of the spacecraft design, such as a constant radiation
pressure.

There may be other forms of acceleration or drag peculiar to the spacecraft
that are causing the error, but Kratz tends to think it was IR radiation
pressure and Occam's Razor is on his side. Nobody in the physics community
seems willing to suggest that it is anything but an anomaly restricted to
certain spacecraft.
Anderson himself admitted that he feels it has an internal cause in his
publication
in Physical Review.

As for Ben's commentary about RTG's getting cooler, the halflife of
Pu 238 is 87.75 years; it will not change that much over twenty years, the
greatest
delta being distance to the Sun.

Now, why aren't Voyager 1 and 2, as well as every planetary body in the
Solar System perturbed by the same "force" if it is a problem with physics?

The problem here is that nobody likes a mundane explanation, because a good
one destroys blind speculation. I've noticed that a few members  of the
Starship
Design list have recently commented that they prefer blind speculation and
don't like skeptics. Oh well.


-Gene