Re: [FT] sensors

laserlight@quixnet.net wrote:
> Reading through other parts of Nyrath's site, I saw discussions of how
a
> drive plume can be detected from here to Antares, but I didn't notice
> anything about how far away you can detect a ship which is using an
> Handwavium drive, which (as everyone knows) has no rocket exhaust.  
> Let's say you move by generating a small black hole in front of you
and a
> negative mass equivalent (generates a push rather than a pull) behind
you.  
> a) how would this be detected?
> b) how far away could you reasonably expect to detect a ship, just by
its
> temperature?

	I cannot answer [a], but the answer to [b] is on my site
	at http://www.projectrho.com/rocket/rocket3w.html

	Assuming the ship is running silent (i.e., not using
	a fusion exhaust with an energy of 2.5 terawatts)
	the minimum detection range will depend upon the
	enemy seeing the ship due to the infrared heat
	of its hull.

	No, you cannot defeat this by refrigerating the hull,
	see the website for detail.

	The equation is:

	Rd = 13.4 * sqrt(A) * T^2
	where:
	Rd = maximum range the infrared signature can be detected
	with current technology (presumably Full Thrust technology
	will be better) in kilometers
	sqrt(x) = square root of x
	A = spacecraft's projected area in square meters. If the
	ship is a convex shape, the projected area will be about
	one quarter of its surface area.
	T = surface temperature in Kelvins, room temperature
	is about 285-290 k, water freezes at 273 k.

	Lessee....
	A Russian Oscar submarine is 154 meters long and has
	a beam of 18 meters.  If it was a spaceship, and was
	nose on to you the area would be 250 square meters.
	If it was broadside the surface area would be
	approximately 2770.  So on average the projected
	area would be 1510 square meters.

	If the Oscar's crew was shivering at the freezing point,
	the maximum detection range of the frigid submarine
	would be about 38,800,000 kilometers,
	or about one hundred times the distance between
	the Earth and the Moon, or about 129 light-seconds.
	If the crew had a more comfortable room temperature,
	the Oscar could be seen from even farther away.