Of pinnaces, gravity plates and detecting the spider drive.

--snipping--

SharkHunter wrote:--snipping--
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I'm talking about the ability to detect particles being affected by "stealthed spider ships under power and in motion", using tractor beams that then have to reach through heavily charged particles. Keep in mind, here from planet earth we are currently detecting planets at thousands of light years range by the deflection of light particles, using "pre-diaspora" technology supposedly 4000 years older than the Honorverse.
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[quote="SharkHunter"
I'd imagine that you could probably pick up a spider drive's effect on a maybe a km or larger diameter or so section of space filled with aurora borealis bright particles..

[astronomer hat]
I am an planetary scientist. My specialty was occultation studies, which is basically studying the shadow produced by a planet passing in front of a star.

Your counter-example of the detection of planets at thousands of light-years is irrelevant. Those observations required literally years of data. Your bombs will create a glowing plasma cloud for mere fractions of a second. The cloud will not be able to expand very far in that amount of time. Secondly, the surface brightness of the star is enormously greater than the effective surface brightness of the cloud you are positing.

How exactly do you think these tractor beams will detect these heavily charged particles? The tractors don't have any way of determining how many particles are in the beam, or how far away they are. There is no way for the tractor to detect any kind of wake or disturbance in the propogation of the particles. The only way to detect it is to actually have a detector in the shadow. In addition, you would only want to explode a single bomb at a time if you are trying to detect particles. Multiple explosions will mess everything up. Like 500 lights illuminating a room from different directions, there won't be any shadows. If you are blowing up 500 bombs, do you really think that each bomb can fill a volume equal to 25,000 Earths with a glowing aurora?[/quote] The planetary scientist bit just made me go "oh yeah, that's right! on how long the phenomenon had to be observed at what luminosity", so I am surrendering "the point".

My thought behind the "500 blasts" had been that the timing of multiple blasts at C, crossing that space would be (by nature and taking advantage of distance) imperfectly synchronized, and that would be what would cause at least an energizing effect on any particles in between to persist AFTER the blast(s) just long enough for a "tractor beams moving through the fluoresced field" to cause a sufficient enough disturbance enough that tuned sensors would then localize the "spiders in motion".

At worst it would screw with the stealth shielding computations quite a bit, having to figure out how to pass all of those explosion's "visual and energy sig info" on to the other side of the ship in a 'correct sequence', sort of like "500 Megaton lidar pulses" from every angle in a 3-5 second interval.

SharkHunter wrote:My thought behind the "500 blasts" had been that the timing of multiple blasts at C, crossing that space would be (by nature and taking advantage of distance) imperfectly synchronized, and that would be what would cause at least an energizing effect on any particles in between to persist AFTER the blast(s) just long enough for a "tractor beams moving through the fluoresced field" to cause a sufficient enough disturbance enough that tuned sensors would then localize the "spiders in motion".

I think I get what you are getting at, but I don't see how the tractors do anything useful. Either the field is fluorescing or it isn't. If you can detect the fluorescence and lack of fluorescence, great. I don't see how the tractor helps, though. All it would do is mix the material up more, which would blur the aberration in fluorescence rather than make it more detectable.

In any case, the blast is not going to make the pre-existing particles glow any more than they already do. The interplanetary medium has a temperature of thousands of degrees. But there are so few particles that it isn't detectable except through extremely long light-paths. The deviation caused by a mere 1 km object isn't going to be measurable.

At worst it would screw with the stealth shielding computations quite a bit, having to figure out how to pass all of those explosion's "visual and energy sig info" on to the other side of the ship in a 'correct sequence', sort of like "500 Megaton lidar pulses" from every angle in a 3-5 second interval.

Yes, I agree that it would mess up the stealth computations. But that would only be observable by a detector actually in the shadow. In my earlier post, I assumed that the holographic stealth paint would not be able to keep up with the intensity and spectrum of the blast when I said that it would take trillions of detectors to be sure you were in the shadow. If the stealth paint were somehow able to keep up (hah!), there wouldn't be any shadow of e-m radiation in the first place.

The only way I can think of to detect the spider drive in fairly short ranges would be microgravity lensing.


Whether that works would depend on the sensitivity of optical instruments in the Honorverse.

Belial666 wrote:The only way I can think of to detect the spider drive in fairly short ranges would be microgravity lensing.


Whether that works would depend on the sensitivity of optical instruments in the Honorverse.

Microgravity lensing, like most of the other ideas proposed, requires having a detector in the right place. It still takes billions of detectors to work.

SWM wrote:Microgravity lensing, like most of the other ideas proposed, requires having a detector in the right place. It still takes billions of detectors to work.

Depends on how sensitive your detector is. If a detector with sensitivity A can detect microgravity lensing in a thousand-kilometer radius from a 10-megaton mass, then a detector with sensitivity 1 million A could detect microgravity lensing in a million kilometer radius.



Alternatively, you got a gravity detector weighing a million tons. A 10-megaton starship would produce 6.67e-10 Newton of "pull" from a distance of 1 million kilometers. Assuming your detector has enough sensitivity to notice that kind of "pull", you could tell where the starship is at that distance.

Belial666 wrote:

SWM wrote:Microgravity lensing, like most of the other ideas proposed, requires having a detector in the right place. It still takes billions of detectors to work.

Depends on how sensitive your detector is. If a detector with sensitivity A can detect microgravity lensing in a thousand-kilometer radius from a 10-megaton mass, then a detector with sensitivity 1 million A could detect microgravity lensing in a million kilometer radius.

Alternatively, you got a gravity detector weighing a million tons. A 10-megaton starship would produce 6.67e-10 Newton of "pull" from a distance of 1 million kilometers. Assuming your detector has enough sensitivity to notice that kind of "pull", you could tell where the starship is at that distance.

Ah, you aren't talking about lensing at all--you are talking about a gravitational detector.

I'm afraid that the mass of the gravity detector is irrelevant. In freefall, there are only two ways to detect a gravitational field. One is to have a strain gauge that measures the stress caused by one part of the device being closer to the gravitational source than another part of the device. The mass of the device is irrelevant; the only thing that it will measure is the difference in acceleration between the two parts of the device.

The other way to detect a gravitational field is to measure the acceleration itself. In freefall, this would have to be done by constantly monitoring and tracking separation of the device from other objects which lie considerably further away from the gravitational source. Once again, the mass of the detector is irrelevant--the acceleration is independent of the mass of the detector.

One way to do it would be to have an array of devices, each of which constantly measures its separation from several other devices in the array. In essence, the entire array becomes a strain gauge, as described above.

This is a plausible solution. I think we have discussed this elsewhere in detail, haven't we, Belial? Let's see what acceleration we can expect to measure with this system. Let's assume the stealth ship is 10 Mt. If one of the devices in the array is 1 light-second from the ship, it will experience an acceleration of 7.5e-19 gees. It would not feel the acceleration, of course--it is in freefall. It would only be able to measure this acceleration by measuring the changes in separation from other devices further away.

With 7.5e-19 gees, the device will shift out of its expected position by 4.8e-11 meters in one hour (assuming that the ship continues to be 1 light-second away from the device the entire time). That's the wavelength of hard x-rays. Of course, the ship is likely moving with respect to the array. With a more practical measurement time of 1 minute, the deviation will be only 1.3e-14 meters.

Unfortunately, I don't think that it would be possible to measure aberrations in separation on the scale necessary. We are talking differences in position smaller than an atom. It's a clever idea, but the accelerations are too miniscule. If you can get a detector as close as 1 light-second, David has already hinted that there are other ways to detect the stealth ship.

1) The detector doesn't need to be in freefall. You can tractor it behind the ship so it's outside the compensator field and measure how it's influenced by external forces while known forces are applied to keep it in place.

2) The detector can be the ship itself, the compensator compensating for all forces applied. How accurately can Honorverse technology measure the compensation needed?

3) The gravity detector is a separate option from the gravity lensing. For gravity lensing, you could look for the enemy ship. You could also look for the 100k-kilometer-long tractors exerting tens of thousands of gravities. What happens to any light crossing the path of the tractor?

Belial666 wrote:1) The detector doesn't need to be in freefall. You can tractor it behind the ship so it's outside the compensator field and measure how it's influenced by external forces while known forces are applied to keep it in place.

2) The detector can be the ship itself, the compensator compensating for all forces applied. How accurately can Honorverse technology measure the compensation needed?

I'm afraid that both of those cases are still in freefall. It is in freefall unless the detector is held in place relative to the source of gravitation.

In Case 1, the only thing that the ship can measure is how the detector is accelerated relative to itself. The ship does not lock itself into place relative to the entire universe. The ship is affected by the same acceleration forces that the detector feels. Both the ship and the detector will experience approximately the same acceleration, so their positions relative to each other will not change. There will be a very slight difference in the acceleration felt by the detector compared to the ship--that is exactly what I was talking about with the description of a strain gauge. It is measuring the difference in acceleration between the two things. And I've already shown that the acceleration itself is miniscule; the difference in accelerations is orders of magnitude less.

In case 2, the ship itself is in freefall. The inertial compensator does not have to compensate for anything, because the ship doesn't feel any acceleration. It's just like a man sitting in a spaceship in orbit; both the ship and the man are being accelerated by Earth's gravity, but the man inside the ship can't tell. He is floating in the middle of his ship, and both ship and man accelerate at the same rate and he can't tell he is accelerating unless he looks outside the window and realizes the stars are going around in a circle. The force felt by the inertial compensator is zero. As I said before, the detector can only measure its acceleration by measuring it's changing position relative to other objects further away from the gravitational field.

3) The gravity detector is a separate option from the gravity lensing. For gravity lensing, you could look for the enemy ship. You could also look for the 100k-kilometer-long tractors exerting tens of thousands of gravities. What happens to any light crossing the path of the tractor?

That is an interesting idea. But I don't think you can assume that the "tractors" actually act like normal tractors, and you definitely can't count on the "tractors" extending for a hundred thousand kilometers. My impression is that these beams which have been described as acting like tractors on the hyperwall extend a limited distance from the ship, perhaps tens of kilometers or a few hundred at most.

Presumably, the microlensing will only affect light actually passing through the beam. Simply passing near the beam is not enough. Assuming the ship is moving relative to the detector, a microlensed star image would spend an extremely brief period of time in the beam.

Such a flicker would be readily detectable if it greatly magnifies the light. Unfortunately, the amount of magnification is limited. The magnification in intensity is not limited by the strength of the gravitational field--it is limited by the effective light-gathering surface area. For a normal gravitational field, that is related to the strength of the gravitational field, but for this beam it is related to the width of the beam. And the beam is going to be pretty narrow--on the order of meters, at most, I would assume.

Despite the limitations, there may be some merit to the idea. It is possible to measure pretty minute variations in light. Of course, this will have to be done in real-time, which is harder. And it will probably only work if you are already pretty close to the stealth ship, otherwise the target is far too small to have any likelihood of crossing a bright enough star. Essentially, it is similar to the idea we've previously discussed of watching for occultations of stars, except that these beams provide a somewhat larger target than just the ship itself. I have a feeling that the usefulness will be pretty limited. But I'm too tired right now to crunch the numbers. So for now I'll class this as worth looking at further.