[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Engineering Newsletter
> to: firstname.lastname@example.org
> To: KellySt@aol.com
> >>> Heat load on the asimov:
> >> Kelly
> >> This is way outside of my knowledge but couldn't this heat
> >> be expelled like exhaust and added to the thrust? Heat is
> >> just hot particles, isn't it?
> No such luck. Heat is eiather the thermal vibration of the molecules in an
> object, or infared radiation (life in a radiative heater). Can't think of
> how we'ld pump all the heat out of the ship fast enough to keep it cool.
Heat is purely statistically random molecular motion. Infrared
radiation is just a form of radiation that is good at inducing
heat in common materials.
Regarding this whole momentum-transfer issue, in some far-distant
posting to the newsletter I pointed out that a reflective sail is
the most efficient option for accelerating a spacecraft with
beamed power; it changes photons with momentum +p into photons
with momentum -p, and thereby increases the spacecraft momentum
by 2p. It is unlikely that you could absorb the photons and use
them to power a mass driver with greater efficiency than the
reflectivity of a mirror.
Using beamed power to decelerate a ship that's going in the same
direction as the photons is more problematic. At best the
efficiency is going to be bad.