On Feb 26, 8:25=A0am, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> On Feb 25, 8:05=A0pm, Tim Little <t...@[EMAIL PROTECTED]
>
> wrote:
> > Or 100 km^2 for a 1 GW mass driver of perfect efficiency (which is
> > still too small). =A0At that size you'd need the radiator to be
edge-on
> > to the Sun, else deal with dozens of gigawatts of solar flux.
> Well, in regards the OP's concept, you have a multi-gigaton asteroid
> to work with. How long will it take to heat up X-gigatons from 10K or
> whatever the asteroid is at to begin with to a temperature where it
> begins to stand out?
The amount of waste heat generated is proportional to the
amount of kinetic energy pumped into the exhaust, which
is proportional to the mass of the asteroid. Thus, the effect
of mass more or less cancels itself out.
However, the amount of kinetic energy pumped into the
exhaust is also dependent on the desired mission delta-v.
The original concept assumed it's okay to wait decades
for the mission to complete, so the required delta-v
might not be so daunting.
> Personally, I don't hold high hopes for it
> succeeding, but you do have a mighty big heat sink to work with,
> enough perhaps to hide at least the initial phase of the operation.
> Combine that with a radiator hidden in the shadow of the asteroid and
> you might be able to do it. Do people look for asteroids in the IR?
Not today, because Earth's atmosphere gets in the way.
Space based IR telescopes currently spend their time
looking at more scientifically juicy targets. It's a gap in
sensor coverage which will be filled in when we expand
significantly into space.
Isaac Kuo
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