[ExI] SpaceX launch

Eugen Leitl eugen at leitl.org
Fri Dec 10 10:05:57 UTC 2010

On Thu, Dec 09, 2010 at 02:28:45PM -0800, Adrian Tymes wrote:

> Indeed.  I would very much like to see viable plasma thrusters that can
> generate 1G+ of thrust.  The trick seems to be either generating or storing

Electrip propulsion is low-thrust high-Isp (current VASIMR does
4 N, 6000 s specific impulse). The advantage of LEO-LLO plasma-driven
transfers is not time (currently ~6 months) but low propellant usage, 
making maximal use of each kg to LEO. Unmanned payloads can also tolerate
much higher deccelerations on landing.

Specific advantage of VASIMR is that you don't need do
do efficient but long-duration Hohmann transfers but go directly 
high energy transfer orbit which is mostly relevant for manned

> that much plasma, without ruining the thrust to weight ratio (when including
> the plasma generating/storing equipment, including any power supplies
> that need to be carried by the rocket).
> I wonder if there's a chemical reaction that can take its reactants up to
> plasma phase, without need of external input?

No, chemical bond energies are orders of magnitude below that
required. You'd do much better using nuclear sources, like
solar photovoltaics (with the added advantage that you're
not carrying the power source) and nuclear reactors driving 
the electric propulsion unit.
> >> Until then, launching to what space station there is will have to suffice,
> >> so far as the launcher end of things is concerned.
> >
> > Please do not top-post and please trime your mail.
> Please typo-check and please don't quote entire emails without adding
> anything but a period and your signature (as your email immediately
> following this one did).

Several, in fact. I'm glad you noticed.

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
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