[extropy-chat] delta 4

[Mike Lorrey]

--- "Robert J. Bradbury" <bradbury at aeiveos.com> wrote:
> 
> 
> On Fri, 12 Dec 2003, Mike Lorrey wrote:
> 
> > ... joined together and can lift up to 13,130 kg (28,950 pounds) to
> > geosynchronous transfer orbit. [snip]
> ...
> > This booster competes directly with the space shuttle. That cargo
> size
> > is for GEOSYNCH!!!!
> 
> This is probably a question for Mike or Spike -- I'm curious does one
> gain anything by sacrificing time-to-geosync?  We have the example
> now of the Europeans taking the slow boat to the moon with Smart-1
> using ion propulsion -- does one gain anything by using ion
> propulsion
> to get sats from GTO into GSO even though it might take months
> instead
> of hours?  (Xenon is certainly heavier than other solid or liquid
> fuels...)
> Are ion engines inherently lighter or heavier than traditional rocket
> engines?

They are lighter, but the real advantage is that you don't need as much
fuel. The electricity from your solar panels or other power sources
accellerates less fuel to a higher velocity, so your isp is several
times higher, at a minimum, than chemical rockets. So long as you don't
have any people on board with limited supplies, you can save lots of
fuel mass by taking your time with an ion engine.

 Time is the trade off only because ion and plasma engine thrust levels
are extremely low, from thousandths of pounds up to fractions of pounds
with ion engines, to several pounds of thrust with the biggest plasma
thrusters. Plasma engines have higher thrust but lower isp than ion
engines.

By saving fuel, you can obviously either carry more science on board,
or you can use a smaller booster to get into space. Either way gets you
more science for the buck.

=====
Mike Lorrey
"Live Free or Die, Death is not the Worst of Evils."
                                       - Gen. John Stark
"Fascists are objectively pro-pacifist..."
                                       - Mike Lorrey
Do not label me, I am an ism of one...
Sado-Mikeyism: http://mikeysoft.zblogger.com

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