Gravity Sensors vs Cloaking Devices

[trackball]

'lo all.
Long time reader, first time poster. I've searched extensively for an in-depth analysis of this topic in the forums but came up empty.
I crunched some numbers, and I don't believe that a Star Destroyer would be able to detect a cloaked Star Trek vessel while inside of a solar system. Now maybe this has been done in the novels (I don't know, I haven't read any) and I won't pose any argument against gravity sensors being able to detect a vessel out in deep space, but inside of a solar system, it doesn't seem possible.

This is the situation I ran:
The equation for the force of gravitational attraction is F=Gm1m2/r^2.
Put a Star Destroyer in geosynchronous orbit around the Earth (4.216E7 meters from the center of the Earth, 3.482E8 meters from the moon, 1.496E11 meters from the sun (source: www.nineplanets.org)
Put a cloaked Galaxy Class starship 1,000km away.
The mass of a Star Destroyer is 9E10kg (source: Mike Wong's analysis of Imperial production capacity)
The mass of a Galaxy Class starship is 4.5E9kg (numerous sources agree).
The mass of the Sun is 1.989E30 kg
The mass of the Earth is 5.972E24 kg
The mass of the Moon is 5.753E22 kg (source: www.nineplanets.org)
The universal gravitational constant (G) is 6.672E-11 Nm^2/kg^2

Crunching these numbers gives the following gravitational forces between objects:
Earth and Star Destroyer: 2.018E10 N
Sun and Star Destroyer: 5.337E8 N (56,000 short tons)
Moon and Star Destroyer: 3.729E6 N
Galaxy Class starship and Star Destroyer: 2.702E-2 N (less than 1/100 of a pound)

What this means is that all those massive planets hanging around will flood the Star Destroyer's gravity sensors with such enormous amounts of interference, it's jamming the sensors. This isn't a matter of making the sensors more sensitive, or increasing their resolution, or making sure they have a nice wide range they can reliably detect, it's a simple matter of the Galaxy Class ship being lost in the randomly generated noise all around. This noise can come from any number of sources, including variations in density (planets and stars are not uniformly dense) and random large comets and asteroids that are cluttering up interplanetary space.

Assuming the Star Destroyer can tell the difference between random noise and a tiny Star Trek ship by an extremely generous factor of 100,000 times, the Star Destroyer would have to be 1.152E11 meters away from the nearest Earth-sized object (that's roughly 1 AU). This leads me to the conclusion that a cloaked Galaxy Class ship would be undetectable while inside a solar system.

Incidentally, this is how the Stealth Bomber works. It does, in fact, reflect radar waves, but only as much as a large bird. Just as a radar station can't be launching anti-aircraft missiles every time a bird passes by, the Star Destroyer crew can't be jumping to Red Alert every time a tiny sensor blip shows up.

Just for fun, let's put another Star Destroyer flying in formation with the first one, at a distance of 1 km (about what I recall from the movies). The gravitational force between the Star Destroyers is a whopping 5.404E5 N, still plenty to flood the sensors and make the Galaxy Class ship indistinguishable from sensor noise. Keep in mind that Mike Wong's estimate of a Star Destroyer's mass is only 20 times the mass of a Galaxy Class starship, which seems low to me since a Galaxy Class starship is held together with force fields and a Star Destroyer is apparently held together with bolts and welding. The greater the mass of the Star Destroyers, the more sensor jamming they would cause each other.

Conclusion: The only way a Star Destroyer would be able to detect a cloaked Star Trek ship is if it were completely alone and well outside of a star system, the presence of large stellar masses would create a natural sensor jamming. However, if this has been contradicted in the novels, there's not much I can say about that. Regardless of plausibility, if it's canon, I must accept it.

I'd appreciate if anyone would double-check my facts and math. In any case, this wouldn't change the fact that the Empire would still win, we'd just have a bunch of Trek pirate ships flying around afterward, using their transporters to steal food, fuel, and supplies to survive. And probably the odd protocol droid, just because it would be handy to have around.

[omegaLancer]

Problem while a Starship is cloak it still emitts radiation. The Enterprise was able to target a Cloak Klingon bird of prey ( one that could fire while cloak) with a Photon torpedoe that had a ion detector added..

Even in balance of terror the Enterprise was able to Track the Romulian ship while it was cloaked..

Soooo with the wide range of sensors available to a star destroyer what going to stop it form detecting Infra red radiation ( A starship still got to radiate heat to space) or ions from it Impulse engineers.. And lastly the massive gravtiy waves that are emitted when their warp engines warps space...

And even if a ST vessel get off first shot the return fire would fry it...

[Ted C]

Detecting a cloaked starship by the gravitational force it generates is simply a matter of the sensitivity of the instruments and the ability of the ships computers to correlate data from other systems.

You need the sensitivity to detect the relatively small amount of force that a starship generates compared to something like a moon. You need correlation with other sensors to know that the small gravity well you're detecting isn't generated by something you can already see, like an asteroid or a ship that you can see on other sensors.

In short, the detection isn't limited by what massive objects happen to be in the vicinity; it's limited by the technology at your disposal. The crystal grav-trap sensor described in the Star Wars literature has the necessary sensitivity and computation power to detect small, cloaked asteroids, so it should be able to detect cloaked starships.

[NecronLord]

It's a simple matter to cut out that interferance. Do what you did and overlay it onto the sensor data, If any object that remains is moving in a non orbital path, then it's a cloaked ship.

[Illuminatus Primus]

This is completely and utterly false.

Your conclusions are irrelevent, as we know SW grav sensors like the CGT can pick up SW cloaked asteroids, which are far more passive and less massive than large warships.

Not to mention that other passive EM scans can pick up ST cloaked vessels or their propulsion.

[Illuminatus Primus]

Not to mention they knew it could pick up cloaked asteroids floating amongst Coruscant level traffic, which is truly enormous.

SW gravsensors are very impressive, apparently.

[trackball]

Not to mention they knew it could pick up cloaked asteroids floating amongst Coruscant level traffic, which is truly enormous.
SW gravsensors are very impressive, apparently.

Could you provide a source for this?

[Illuminatus Primus]

The Last Command, by Timothy Zahn.

The Chimaera and her escorts drop into low orbit around Coruscant and drop cloaked asteroids into low orbit to effectively blockade Coruscant (they can't allow any of them to slip through the shield and impact the surface, killing billions).

[Rightous Fist Of Heaven]

In one of Stackpole's NJO books the Ralroost scans an entire solar system searching the mass signatures of Coralskippers. They thought that if the skips would be somewhere they would be in an asteroid field and the grav sensors on the Ralroost are clearly sensitive enough to detect singular skips in an asteroid field by their mass and grav.

[Crazedwraith]

Your conclusions are irrelevent, as we know SW grav sensors like the CGT can pick up SW cloaked asteroids, which are far more passive and less massive than large warships.

was that ever proved? I mean from what i remember of "the last command", they never said it would work just that it was their best shot.

[trackball]

Your conclusions are irrelevent, as we know SW grav sensors like the CGT can pick up SW cloaked asteroids, which are far more passive and less massive than large warships.

was that ever proved? I mean from what i remember of "the last command", they never said it would work just that it was their best shot.

This throws a monkeywrench into things. How was this problem actually solved in the book? Using my (generous) factor of 100,000 times to differenciate between sensor noise and an actual object, I calculate a ship would have to be within 10 meters of an asteroid in low orbit to detect it through the natural jamming of the planet.

In one of Stackpole's NJO books the Ralroost scans an entire solar system searching the mass signatures of Coralskippers. They thought that if the skips would be somewhere they would be in an asteroid field and the grav sensors on the Ralroost are clearly sensitive enough to detect singular skips in an asteroid field by their mass and grav.

What is the mass of a Coralskipper? And what is it?

[Rightous Fist Of Heaven]

Its a Yuuzhan Vong snubfighter with a mass of 10-15 tons i think. Considering that its a bit larger than an X-wing but has more volume.

[Ted C]

This throws a monkeywrench into things. How was this problem actually solved in the book?

Interestingly enough, the CGT sensor wasn't actually used to locate the cloaked asteroids in the book. The New Republic had been dumping "chaff" out of ships to locate them, and had actually found all of them (Talon Karde told them how many he had seen being prepared at one of Thrawn's bases) before the CGT sensors were available.

[trackball]

Its a Yuuzhan Vong snubfighter with a mass of 10-15 tons i think. Considering that its a bit larger than an X-wing but has more volume.

I hate to have to ask this, but in light of Crazedwraith's response to Illuminatus Primus, I must ask anyway.

Did they actually find the Coralskipper? And if not, is there any canon evidence of actually succesfully finding a ship, in a star system, with gravity sensors alone?

[Illuminatus Primus]

Point was, they figured it would do the job, and we see in the NJO grav scans searching much larger areas for much smaller objects.

[Crazedwraith]

Point was, they figured it would do the job, and we see in the NJO grav scans searching much larger areas for much smaller objects.

They thought it might do the job we never heard if it worked.

[Illuminatus Primus]

Its a Yuuzhan Vong snubfighter with a mass of 10-15 tons i think. Considering that its a bit larger than an X-wing but has more volume.

I hate to have to ask this, but in light of Crazedwraith's response to Illuminatus Primus, I must ask anyway.

Did they actually find the Coralskipper? And if not, is there any canon evidence of actually succesfully finding a ship, in a star system, with gravity sensors alone?

I hate it when people say "well they used it for a specific purpose but there is NO evidence it could actually do it."

If you look at what they wanted to do with the CGT, and combine it with this, than it is no biggie.

SW has supernatural control of gravity. Afterall, they can warp space-time enough to limit manuverability without this costing more energy than the DS's main weapon.

[Illuminatus Primus]

Basically they can do it--realism thereof is excusable--it is suspension of disbelief.

[trackball]

I hate it when people say "well they used it for a specific purpose but there is NO evidence it could actually do it."

I really don't see it this way. These two examples given appear to be last-ditch million-to-one shots that "just might work". But they were never shown to have actually worked, so they are useless as examples.

Granted, the Empire has shown supernatural control over gravity, but only in a brute-force kind of way. This requires precision.

Also, I'm not trying to declare that it can't be done just because it hasn't been, so I feel your eyeroll was inappropriate. I'm doing this in stages.
Stage 1: HAS it been done? So far, the answer is apparently no.

[Illuminatus Primus]

Not really. A Bothan cruiser hopped in and scanned for YV ships. The Republic was told by Karrde that all the asteroids were destroyed, and Leia believed him, but the Council wanted to be sure, so they refused to open the shield until a CGT was captured and used to double-check Karrde's claim.

Not last-ditch effort.

[Illuminatus Primus]

Not to mention that throughout Destiny's Way and Star By Star, the Star Wars vessels were able to detect tiny levels of gravitational waves being used by a yammosk as communication.

[Crazedwraith]

Not really. A Bothan cruiser hopped in and scanned for YV ships. The Republic was told by Karrde that all the asteroids were destroyed, and Leia believed him, but the Council wanted to be sure, so they refused to open the shield until a CGT was captured and used to double-check Karrde's claim.

Not last-ditch effort.

IIRC They were all ready preparing for the mission when Karrade came and told Leia. The High Command a) didn't trust smugglers like Karrede b) had already expended to many resources on the operation to call it of.
IMHO the operation was a last-ditch attempt to try and be sure they'd gotten rid of the cloaked asteroids.

[trackball]

Not really. A Bothan cruiser hopped in and scanned for YV ships. The Republic was told by Karrde that all the asteroids were destroyed, and Leia believed him, but the Council wanted to be sure, so they refused to open the shield until a CGT was captured and used to double-check Karrde's claim.

Not last-ditch effort.

Not to mention that throughout Destiny's Way and Star By Star, the Star Wars vessels were able to detect tiny levels of gravitational waves being used by a yammosk as communication.

Let me make sure I understand you correctly, as I said I haven't read the book. Are you talking about the cloaked asteroids in low orbit around Coruscant or the asteroids the Coralskipper was hiding in? Or are you talking about both of them and I'm just confused that you put them in the same paragraph?

And were these gravitational waves being detected from a piont located inside or outside of a star system? It makes a difference, as there is very little gravitational sensor jamming (the basis of my argument) outside of a star system.

[Crazedwraith]

Not really. A Bothan cruiser hopped in and scanned for YV ships. The Republic was told by Karrde that all the asteroids were destroyed, and Leia believed him, but the Council wanted to be sure, so they refused to open the shield until a CGT was captured and used to double-check Karrde's claim.

Not last-ditch effort.

Not to mention that throughout Destiny's Way and Star By Star, the Star Wars vessels were able to detect tiny levels of gravitational waves being used by a yammosk as communication.

Let me make sure I understand you correctly, as I said I haven't read the book. Are you talking about the cloaked asteroids in low orbit around Coruscant or the asteroids the Coralskipper was hiding in? Or are you talking about both of them and I'm just confused that you put them in the same paragraph?

And were these gravitational waves being detected from a piont located inside or outside of a star system? It makes a difference, as there is very little gravitational sensor jamming (the basis of my argument) outside of a star system.

two diffrent stories
In the book"The Last Command" Thrawn dumps a whole load of cloaked asteriods around coursant.

They scan 4 corall skipers in the NJO series of books which is set much later.

[trackball]

Assuming that Crazedwraith can answer for you, Illuminatus Primus, since he read the books, I will concede defeat if:

1) Corsucant's traffic was not cleared out when they scanned for the asteroids,

or if

2) The CGT (whatever that stands for) scanned Couscant's orbit from the planet's surface.

Either of these would prove that they can somehow read through intense gravitational jamming.