On Hydrogen Fuel

"H2-PV NOW" wrote in message
oups.com...

John Doe wrote:
H2-PV NOW wrote:
If you know you need fuel for return, taking H2O is the most compact
form, and considerably safer than than carrying around excess flamable
gases before you actually need the gases.

This is an interesting argument. Consider a voyage to Mars for instance.
Solar arrays could continually electrolyse water to provide not only O2
for cabin, but also O2 and H2 for propulsion. And the water would also
serve as shielding.

I guess I should have been more clear and said that my interests are
Spaceplanes SSTO to LEO. Going to Mars without a Lunar base is, well,
Lunacy. A lot of what you might want for a trip to Mars is
prepositioned on the moon, where the launch penalties are far lower.

My interests are not intellectual but actual. I want to enable the SSTO
and LEO habitat efforts and then GEO and L-5. A step by step effort
means that travelling to Mars is on a luxury liner, not in a cramped
tin can with your fellow's unwashed smelly feet drifting into your face
all night packed like sardines, slowly going insane.

Of course tastes differ, and some people actually prefer spending five
or more years of their life in conditions similar to a blend of
third-world prison cell and a homeless shelter with guys who don't
bathe too often.

Yes, water is a luxury item in space, and as of right now, Earth is the
only certain place to get any. A single gallon of it weighs 8 pounds,
and according to NASA, that makes a gallon of water worth $80,000 at
the International Space Station, wholesale, before tax and dealer prep.

Did you know that at the ISS they dump their **** overboard, at $80,000
a gallon for that too? You'd think with vacuum close at hand and
nightime temperatures below freezing, they could freeze-dry purify it.
Or daytime temperatures steam distill it. Maybe if they had to pay for
supplies lofted to orbit they might think better, but they have a rich
uncle sugar who pays all their bills, so they don't have to think.

However, you would still need storage for H2 and O2 for the major
propulsion events. For instance, for orbit insertion at Mars, you'd need
to have enough fuel stored to do the burns to do a quick orbit
insertion.

I guess you have a rich uncle sugar too...

So you'd need to be building up some O2 and H2 tanks slowly
over time so that they are full at the time you need to do a large burn
in a short amount of time (entering orbit, leaving orbit). The advantage
is that you'd re-use the tanks for multiple events isntead of carrying
tanks for each of the 4 big events (leave earth, arrive mars, leave
mars, arrive earth).

NOBODY is going to Mars like that. It's not just an Apollo mission writ
larger..


But if it takes you months to fill thsoe tanks by using solar power to
electrolyze water, then you need to have tanks capable of storing h2 and
O2 for months.

I could have sworn I answered that objection in the message above in
the thread. Let me look...
http://snipurl.com/mqu0
Yup, there it is...

The Homopolar Generator is portable, works everywhere in the universe
as far as I know, as far as anybody knows right now. You make a disk
out of a conductor and add a magnet layer to it and spin it. While
there is no gravity drag on it in zero-G it still hass mass which
requires power to spin it. However it need have no friction, which is
more serious than gravity drag, but then it has electrical reactance
which adds up over time. While you won't get a free lunch out of such a
thing you can get astronomical amounts of power (literally,
astronomical).

The reason you don'y know more about homopolar generators is because
they are used on hush-hush classified stuff like driving nuclear sub
propellers, or experimental railguns for tanks. Some applications are
proprietary because companies don't want to tell the competition how
they are doing what they do, like welder power supplies and
electrolyser units.

A quick Google search doesn't give me much hope that they even work, let
alone that they are being used in real world applications. Do you have
unbiased analyses or examples from somewhere?