Sorry, not true. Its all how you apply it. There is minimum, but how
and when you apply it, but, as NASA has learned with their gavity assist
maneuvers, as well as BMDO with Clementine, minimum energy maneuvers are
extremely efficient. They just take a long time.
>
> > You could even have small mass
> > drivers using solar power or a garbage can sized fission pile for energy
> > propell asteroids from the main belt toward earth, and use less than .1%
> > of its mass in the process.
>
> AFAIR the L5 folx reckoned it was more like 90% of the mass, and the
> mass-drivers were roughly the same size as those used on the moon.
No, its all realitive to the amount of mass you are using in each
pellet, and the final velocity you need. The lunar mass driver designed
by O'Niel was long enough for people to ride comfortably, with maximum
Gs of less than 9. It was over 75 km long. Hell, thats big enough for
use on Earth to cover 40-60% of launch energy.
Firing small pellets at extremely high velocities (1000G accelerations)
is easy with fairly small drivers. I've built a hand held mass driver
that fired a copper wire slug through an 8" concrete wall. The
capacitors for it took an oxy/acet. cart to lug around. The gauss
evaporated the copper into a plasma and propelled it across the room. As
it passed through the air, the copper cooled into pellets with a LOT of
energy. Major FUN.
You're
> changing your scenario again; if you'd originally said that an asteroid
> belt society (if such a thing is possible) could defend itself against the
> Earth this way then I would probably have agreed. They'd be hard to find,
> hard to hit, and able to cause a lot of damage to Earth.
>
> In the long-run, planets really are a bad place to be.
>
True in a tactical sense, however there are bad places to be and REALLY
bad places to be. Earth is in the latter category, while luna is not so
bad. Don't forget however the childcare problems with low G
environments. You'll have kids with next to no bone or muscle mass,
probalby anemic cardiac systems, etc. unless you take a decent asteroid,
hollow it out, and spin it like Niven's Belters did.
Additionally, I was referring to the bodies in earth orbit that James
referred to, as well as near earth orbit that come within cislunar
distance every few years.
-- TANSTAAFL!!!Michael Lorrey ------------------------------------------------------------ President retroman@tpk.net Northstar Technologies Agent Lorrey@ThePentagon.com Inventor of the Lorrey Drive Silo_1013@ThePentagon.com
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