Realistic gravi-sensors?

[U-95]

Besides a fantasy setting, I've also a sci-fi one whose space battles are a mix of realistic ideas (besides, for example, no sound in space or lasers visible as streaks of light, things as this: http://www.strangehorizons.com/2005/200 ... -1-a.shtml and http://www.strangehorizons.com/2005/200 ... -2-a.shtml) with others not so (FTL travel, shields, etc).

Ok, besides the active & passive sensors mentioned on the articles -including expendable probes mounting them-, another passive sensor system is one to detect close ships -especially those that mount cloaking devices or at least something that resembles them- based on their mass. Basically, it's just two masses one in orbit around the other in an isolated environment with no gravity, air, etc., and very fine sensors lasers?) that detect any deviation of the orbit of both spheres.

Given the weak nature of gravity, it only works for very close range ships, of course. Is there any way to improve it without resorting to technobabble?

[Sarevok]

If you have typical mile long hundreds of million ton to billions of ton sized ships fighting at typical visual ranges (few kilometers) you would not need anything fancy to detect a cloaked object. Asteroids of similar size do generate meaningful gravity such that it is possible for satellites to orbit them if carefully positioned. The acceleration caused by the mass of say, a Romulan Warbird, while it is dramatically posturing a few hundred meters away should be quite measurable.

[Lord of the Abyss]

. The acceleration caused by the mass of say, a Romulan Warbird, while it is dramatically posturing a few hundred meters away should be quite measurable.

Also, since they are powered by a singularity they should IIRC probably produce relatively strong and distinctive gravity waves.

[U-95]

If you have typical mile long hundreds of million ton to billions of ton sized ships fighting at typical visual ranges (few kilometers) you would not need anything fancy to detect a cloaked object. Asteroids of similar size do generate meaningful gravity such that it is possible for satellites to orbit them if carefully positioned. The acceleration caused by the mass of say, a Romulan Warbird, while it is dramatically posturing a few hundred meters away should be quite measurable.

Some races, use as their main power source an artificial singularity like the Romulan ships, so gravity waves could be used to detect them. Excellent; it's an option.

Unfortunately, fights at that range -kilometers and less- are extremely rare except highly peculiar situations such as attempting to board a heavily damaged ship (and with extreme caution since she could self-destruct -and cause serious damage to the boarding vessel in some cases-), and as you say a cloaking device -especially those as the ones used in my setting, that usually work as the one used by the Predator, except that includes all the other bands of the spectrum besides visible light- would not be very useful at so close distances.
For what's close range here (thousands of kilometers), some advanced cloaking systems, however, work very well and it's troublesome with typical sensors to detect a ship that uses it, especially if it's a small one with a size similar to a Dominion fighter or a Klingon B'rel class, and that's why I asked that of gravi-sensors. I imagined a type of dark matter (technobabble, that I dislike) that amplified gravity waves making possible to detect a cloaked ship so close before it fried you with its mass drivers/anti-matter torpedoes/etc, but I wonder if there's another alternative more realistic to something so exotic. Needless to say, the system would work only at short ranges; at medium ones -hundreds of thousands of kilometers- would be nearly useless.


As a final note, besides cloaks, there're other systems to meld with the darkness of the space (super-cooled engines designed to minimize as possible the ionic/etc. trail they leave, ECM, decoys, etc), and of course the fact that some space battles take place on the outer places of a solar system or on interstellar space, where there's little or no sunlight to illuminate a ship.