Stealth Doesn't Work

Poster: Unknown

STEALTH DOESN’T WORK: Space is vast, but mostly empty. Space is also dark and cold; the average background temperature of space is 2-5 Kelvin. Ships with habitable life support sections, even with the engines off, will have a surface temperature of at least 200 to 250 Kelvin (ice melts at 273 Kelvin). For a typical habitable section of a ship, the radiated heat signature is in the range of a few hundred kilowatts, which is generally detectable out to 30,000 km in under a day using a full spherical search pattern with a broad-field IR-band telescope with an aperture of 3 meters. In addition to the waste heat generated by life support, a ship’s power generation system generates heat. A perfect Carnot heat engine produces 2 watts of waste heat for every watt of electricity it produces, where waste heat dissipation is free (like in an atmosphere). In space, waste heat has to be radiated. Minimizing radiator size (to make them retractable in combat, and to make them mass less) means running them at a higher temperature, which reduces the efficiency of the Carnot cycle. Each radiator in AV:T is roughly a 25m x 25m surface radiating from both sides at around 1600 K. Each radiator disposes of roughly 44 GJ of waste heat in 128 seconds, for a signature strength of roughly 340 megawatts, which is detectable (easily) out to around 10 light seconds (3 million kilometers) under the same conditions as the crew’s waste heat. (The distance from the Earth to the Sun is 500 light seconds, as a point of comparison.)

Beyond that, for a 5,000 ton ship using a reaction drive, even in cruise mode, it’s producing a minimum of a 340 gigawatt signature at about 2800 K, which gives a 1 day spherical search pattern “guaranteed” detection radius of a bit over 1,000 light seconds, or roughly 2 AU. In low thrust fuel economy mode, it takes roughly 10-16 weeks to cross 1 AU. During this entire time, the people attempting detection need only look for a 14th magnitude star with measurable proper motion. (A ship in combat thrust puts out drive signatures 10 times as bright, and would be easily detectable out at roughly triple the ranges listed above, or around 6 AU) Finally, any ship using a reaction drive reveals its mass by the correlation between observed rate of thrust and the temperature and brightness/mass spectroscopy of the exhaust plume.

Art Eaton says:

Want real stealth? Get your vector set way, way out where it is harder to detect you. Use a large body to mask your burn, and then use ti to deflect your course to your intended heading. Then you set out a parabolic or corner reflector front of you to reflect radiation away from the direction of your target. The reflectors outward face is probably black RAM to absorb energy coming in, and will be attached to radiators on the BACK SIDE of the reflector (and out of the focused beam of the reflector). This makes the "mask" absorbent in two ways on the inbound side, making it quite well hidden, yet radiates the heat directionally. On one side it is a mask, on the other it is a beacon. You simply cannot have yin without yang in a semi-closed system Vacuum is great for insulation.