Foofad
Aliastra
Gallente Federation
28
   |
Posted - 2012.06.02 02:40:00 -
[1] - Quote
Overall I like your thoughts, but I want to make one correction. Active sensors are the short ranged ones, not passive.
Passive sensors, even today, are phenomenally sensitive. X-ray telescopes, spectrographs, and so on - all of these sophisticated pieces of scientific hardware that you read about - are passive sensors. And that's just what we've got today. Add a dash of space fantasy and there's no reason why a space ship's passive sensors shouldn't be able to detect the electromagnetic emissions of another space ship on the opposite end of a solar system.
Active sensors are needed for precise ranging that doesn't rely on assumptions and known factors. Active sensors are things like RADAR, LIDAR, Sonar, and so on. Active sensors are limited by the amount of energy that can be devoted to them. In order to detect something, an active sensor has to "ping" (like Sonar, echolocation, etc) and then listen in for a reflection. Lasers, like what are used in LIDAR, are very focused beams of light. As the distance grows however, they lose that focus. It's just like the cone of a flash light. As such, the energy requirement to detect something grows very rapidly as the distance increases.
So active sensors are something that you would see used for things like fire control, surface mapping, precise local navigation, missile or drone guidance, things like that. But active sensors are really not that useful over great distances, like if you're trying to detect an object or ship. This is why, for example, we are only just now mapping the surface of the moon with RADAR - we only recently had probes in orbit with that capability, and couldn't do it from Earth or an Earth orbiting satelite. Even WISE, the famed Wide-field Infrared Survey Explorer which is known for detecting and mapping the trajectories of asteroids flying around our solar system, is just a fancy passive telescope. Meanwhile, NASA has a RADAR station that is capable of detecting individual raindrops in a cloud - but only to a range of two kilometers.
Just throwing that out there. It's an important distinction to make. |