[ExI] powersats

[Keith Henson]

On Thu, Mar 27, 2008 at 4:22 PM, Bryan Bishop <kanzure at gmail.com> wrote:
> On Thursday 27 March 2008, Tom Nowell wrote:
>  > I've been following the "getting big loads into orbit"
>  > discussions, and I'm quite a fan of the subject.
>
>  I checked your list. You don't include LOX. The only reason we say "LOX
>  ain't cheap" is because nobody is making it cheap. You have oxygen all
>  around you. You need about 3000 PSI to get it down into the liquid
>  state, and then you're good to go. Let's work with that. Plus, we can
>  get more oxygen from the other side of the atmosphere as well.

Brian, this is just getting the physics wrong.  Long ago there might
have been an excuse, but not with the net.  It is impossible to get
oxygen to the liquid state with pressure alone, the critical
temperature is about -118.6 deg C.  And people do make it cheap, less
than 25 cents a liter.

Fueling the rockets with electrolytic hydrogen is the only reasonable
approach for a really large capacity lift, so while you still have to
make it into a liquid, it come off as a no cost byproduct of making
hydrogen.

Keith