Re: Detection by IR

On 20-Apr-00 at 12:01, Brian Quirt (baqrt@mta.ca) wrote:
> Roger Books wrote:
> > 
> > You know, that does bring up the question of a laser drive.  Point
the
> > laser to thrust.  If the laser happens to be pointing the right
> > directions you could pick it up, otherwise you would see nothing,
> > rec.sf notwithstanding.  As a matter of fact if I throw little steel
> > pellets out (accelerating them with an linac type device) you would
> > never pick them out from earth with passive systems.  (heck, I could
> > cool them to 1K before I accelerate them)
> 
>      a) Laser Drive: Big problem: efficiency. Yes, light has energy.
No, it
> doesn't have very much. The kind of laser that will give you
multiple-g
> accelerations will a) consume an INCREDIBLE amount of fuel and b) be
> VERY bad news for anyone in its path. I recall a discussion on light
> propulsion (inspired by Niven and Pournelle's _The Mote in God's Eye_)

The Moties drive doesn't count, the laser stayed on the planet.  It
was used to heat the reaction mass (ice I believe) on the acceleration
end of the ship.  You waste lots of power but the power is coming 
from the planet where you can  afford the waste.

>      b) Rock drives. Fairly efficient. Require a LOT of reaction mass.
NOT
> very high thrust.

They require no more reaction mass than anything else.	They can also
be very high thrust, it all depends on how fast you throw them out.
When you start throwing out mass it doesn't matter for acceleration
purposes wether it is ice cold rocks or gas heated by combustion.

> If you cool the rocks to 1K, you have to absorb the
> resultant heat yourself.

In deap space, far beyond detection range.  I kind of like this one.
Big circular accelerator.  Before you leave home you spin it up, venting

any excess heat.  When you need to accelerate you release particles,
they
whiz out the back and you whiz forward (or sideways).  Of course the 
whole thing would need to be free to spin so we avoid gyro affects. :)

> Sure, your rocks will be undetectable, but
> you'll make up for it. Also, ISTR that drives based on said principles
> tend to heat the mass in the launching process AND put out em
radiation.
> I may be wrong, of course.

Depends on your process...

I still see your scientific principles as what you believe could work
is scientific even if it requires hand waving, if you don't believe
it could work it isn't scientific.

Roger