On Fri, 09 Nov 2007 17:43:11 GMT, "bumper"
wrote:

I bet it depends on how long you stay up there and how much below freezing
OAT is.

No matter, if you fill your ballast tanks with sawdust, worst case you'll
just end up with "piecrete" popsicles.

Pykrete, after its inventor Geoffrey Pyke. It would offer a few
problems:

1) The contents of your tanks would not freeze into Pykrete. They'd
freeze into ice with a layer of sawdust on top. In order to make
Pykrete you have to agitate the mix constantly until frozen, or
freeze it in layers adding the sawdust as you go.

2) If ballast tanks full of Pykrete froze, you'd have the same problem
you would with plain water ice: landing with a load of ballast aboard.
Better yet, since the drain valves are the most susceptible point for
freezing, you'd run the risk of dumping only one side, which would
make your landing REALLY interesting.

3) Pykrete expands on freezing just as water does, maybe a bit less,
so you'd still run the risk of bursting your tanks.

rj