The Enterprise-D and the Lonka Pulsar

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Mike DiCenso
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The Enterprise-D and the Lonka Pulsar

Post by Mike DiCenso » Sat Jan 28, 2012 8:33 pm

StarWarsStarTrek in the "Vader's Fleet from Empire vs DS9" thread tried to bring up the E-D being only able to withstand exposure to the Lonka Pulsar for 18 minutes in TNG's "Allegiance" [Season 3] as an example of weak Star Trek shields. Apparently he based this off some calculation from SBC, which was of a questionable nature in and of itself. SWST was shown the errors of his ways
, however I feel that a more in-depth analysis at the issue needs to be done.

First some facts. The E-D was brought to 20 million kilometers as stated in dialog:

PICARD 2: Helm take us in to twenty million kilometres.

WESLEY: Aye, sir.

RIKER: Mister Worf, divert enough power to the shields to offset the increased radiation and magnetic fields.

DATA: Sir, at twenty million kilometres, our shields will only be effective for eighteen minutes.

PICARD 2: Noted, Mister Data.


The starship was also exposed to the emissions beam as seen here:

Image

Image

Data's statement of "our shields will only be effective for eighteen minutes" is rather interesting in and of itself as the ship was not shaking or taking any internal damage during all of this. Perhaps he means the shields will hold well enough before the ship and crew are endangered and take damage? Hard to say, but let's assume for the sake of being conservative that he means the shields will totally and completely collapse and the ship will take severe damage instantly and the crew likely killed right then as well.

As noted in the other thread, pulsars, like the Crab Nebula Pulsar, can be as much as 100,000 times more energetic in output than our own Sol, which puts out around 3.8e+26 watts.

For the sake of being conservative, I'll also leave out the emission beam from the pulsar sweeping down over the E-D, which would concentrate a lot of energy at the ship and assume the pulsar is radiating evenly in all directions. I will use the following to calculate the surface area of the "shell" at which the E-D was at at 20 million km radius:

r = radius
A = surface area
C = circumference
π = pi = 3.14159

Thus:
r = 20,000,000,000 m
A = 5.0265482457437e+21 m^2

So now we have a surface area for the imaginary shell, now let us divide the Sun's energy into that area:

3.8e+26 W/ 5.03e+21 m^2 = 76,000 W per m^2.

So if the Sun was all that was involved here it would be 76 kilowatts per meter squared on the E-D shields, which is pretty lousy. The shields would only be taking 17.9 gigawatts total and 19.33 TW in 18 minutes. This is what it looks like the SBC person did since they only calculated a ton or so of energy for the E-D's shields. However, if we plug in the fact that pulsars can be up to 100,000 times more powerful than Sol, we get a different picture:

76 KW x 100,000 = 7,600,000 KW or 7.6 GW per m^2

Now that's quite a bit different results.

To be conservative again, let's assume that the E-D was facing directly at the pulsar to present the minimum possible shield aspect to the radiation and magnetic field (which it was not as seen in the pictures), this would be at least an ellipsoidal cross-section of 500 meters x 150 meters x pi = 235,619.45 meters squared. So we then have the following:

235,619 m^2 x 7.6 GW = 1,790,704.4 GW total or 1,790 TW. That's not a ton of TNT, that's about .4 megatons. In 18 minutes the E-D shields would take 496 megatons. Just shy of half a gigaton's worth of energy!

Now given that the E-D was presenting the much larger surface area of her dorsal shields to the Lonka Pulsar, we would have a shield surface area more like 1,099,557 m^2 and a total energy absorbed each second of 8,356.63 TW or slightly less than two megatons. In 18 minutes the shields would then absorb an incredible 9,025,160.4 TJ or 2.15 gigatons.

Unless someone can find some serious fault with my calculations, I think we can lay the Lonka Pulsar issue to rest.
-Mike

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Re: The Enterprise-D and the Lonka Pulsar

Post by 2046 » Sun Jan 29, 2012 3:11 pm

I would say your calculation quite effectively nullifies any attempt to nerf the example, and parks it squarely within the expected range.

That is to say, someone would have to construct an argument demonstrating that the pulsar is very weak in order to make this a low-end outlier. As it stands after your calc, the example fits the norms one would expect based on other examples of weapons yield and whatnot.

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Re: The Enterprise-D and the Lonka Pulsar

Post by Mike DiCenso » Sun Jan 29, 2012 6:08 pm

Thanks for the vote of confidence, Robert. The numbers do match up well with some of the other examples, and even if we were to claim that the Lonka Pulsar was 1,000 times weaker, we'd still have 20 megaton shields for the E-D.

But remember, because of the emission beam sweeping over the E-D, any numbers you do get will be very conservative. Given that pulsars on average are not more than 100 km in diameter, the emission beam, which is much smaller than that, will be very focused indeed, even out to 20 million km.

I don't even want to think about ramping up the E-D's shields into the tens of gigatons range. It also shows us how badly underpowered the E-D's shields were in "Relics" using only auxiliary power, and if my assumptions are correct, this makes what Voyager went through in "Scientific Method" closing to within 1 million km and then going in right between two binary pulsars possibly the most impressive shield and hull strength example in all of Star Trek.
-Mike
Last edited by Mike DiCenso on Sun Jan 29, 2012 6:42 pm, edited 1 time in total.

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Re: The Enterprise-D and the Lonka Pulsar

Post by Khas » Sun Jan 29, 2012 6:38 pm

I thought pulsars were, on average, 10 km wide. If they are, then wouldn't that make the pulsar's energies even more concentrated?

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Re: The Enterprise-D and the Lonka Pulsar

Post by Mike DiCenso » Sun Jan 29, 2012 7:05 pm

Some pulsars, like the Crab Nebula Pulsar, are 10 km wide, with an "optical width" of 25-30 km, while others are larger. But that has no bearing on the numbers unless the E-D was actually flying right up to the surface of one, and the width of the emission beam might be more concentrated. But remember I am trying to keep the numbers down here to a reasonable level. Otherwise we get the E-D with ICS-level shields!

Then again there is still Voyager flying point-blank between two pulsars:

http://voy.trekcore.com/gallery/albums/ ... od_339.jpg

I mean, come on.
-Mike

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Re: The Enterprise-D and the Lonka Pulsar

Post by 2046 » Mon Jan 30, 2012 12:17 am

As I noted, someone would have to construct an argument demonstrating that the pulsar is very weak in order to make this a low-end outlier. That is, they would need to show that for some reason your higher-end estimates are too high.

Can such an argument be made? Possibly, but probably not.

1. The pulsar has a high mass. The Lonka pulsar is said to be over 4 solar masses, which is supposedly too high for a neutron star (at least in the current science).

a. I do not know if higher-mass pulsars emit stronger beams, though this seems likely.

b. Assuming (a) is true, then the person making the counterclaim would need to sidestep the issue of high mass, possibly by declaring this to be not a pulsar at all based on the current science (e.g. a radiating rotating quark star with properties we cannot guess at). However, to do so would effectively remove the example from consideration (and thus any lower-yield claims).

2. It seems to be a fairly slow pulsar, which may relate to higher magnetic field strength according to recent research.

a. I am also unclear on the mechanism of stream ejection, though this appears to be an issue in the science, too. That is, is the ejection energy dependent on and proportional to the magnetic field strength (in which case slower pulsars, which are generally being considered to have higher magnetic field strength, put out more EM), or are both merely a function of the rotation of the neutron star and thus may even have an inverse correlation?

b. If higher magnetic field strength equals higher stream energies, then the opposing debater would be in a tight spot. However, if higher magnetic field strength correlates to lowered stream energies, then maybe they'd have a spot upon which to stake a claim.

3. The pulsar beam is visible, rather than being exclusively gamma or something.

a. This does not, so far as I know, indicate any particular thing about the beam strength.

b. Opposing views would hopefully be able to argue that this is indicative of a weaker stream.

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Re: The Enterprise-D and the Lonka Pulsar

Post by Mike DiCenso » Mon Jan 30, 2012 3:04 am

On the rotation subject, while the Lonka Pulsar is not the fastest rotating object of it's class, it's not slow either. If you ignore the badly dubbed in Japanese, the video here gives an idea of the rotation speed, which is well under a second as seen at 5:20 where there are two sweeps over the E-D in less than a second. The speeds from the visuals seem a bit inconsistant throughout the remainder of the episode, such as the flashing seen reflecting off the actors and the bridge consoles which suggests faster speeds. The emission beam regardless is definitely hitting the ship.

As for other characteristics, you mentioned it's mass as being four solar masses, but it is actually slightly higher than that:

PICARD 2: What do we know about that pulsar?

DATA: A great deal, sir. It is a rotating neutron star of approximately four point three five six solar mass


Actually 4.36 solar masses, which is actually quite huge by neutron star and pulsar standards.

In fact, this thing is at the limits of mass for collapsing into a stellar black hole.
-Mike

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Re: The Enterprise-D and the Lonka Pulsar

Post by Lucky » Mon Jan 30, 2012 9:30 am

Mike DiCenso wrote:On the rotation subject, while the Lonka Pulsar is not the fastest rotating object of it's class, it's not slow either. If you ignore the badly dubbed in Japanese, the video here gives an idea of the rotation speed, which is well under a second as seen at 5:20 where there are two sweeps over the E-D in less than a second. The speeds from the visuals seem a bit inconsistant throughout the remainder of the episode, such as the flashing seen reflecting off the actors and the bridge consoles which suggests faster speeds. The emission beam regardless is definitely hitting the ship.

As for other characteristics, you mentioned it's mass as being four solar masses, but it is actually slightly higher than that:

PICARD 2: What do we know about that pulsar?

DATA: A great deal, sir. It is a rotating neutron star of approximately four point three five six solar mass


Actually 4.36 solar masses, which is actually quite huge by neutron star and pulsar standards.

In fact, this thing is at the limits of mass for collapsing into a stellar black hole.
-Mike
Seems almost like you should be using a feeding black hole instead of a neutron star in your math?

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Re: The Enterprise-D and the Lonka Pulsar

Post by Mike DiCenso » Mon Jan 30, 2012 6:28 pm

That's tempting, but no. The episode's dialog and the visuals all indicate a pulsar, not a stellar black hole. We just have to assume that by the TNG-era, that they've discovered a class of pulsar that is that big, but for some reason is not collapsing into a singularity. It does leave a lot of room open for this being a high-energy pulsar, just one that does not strictly get it's energy from spinning.

The other thing is that I refuse to go down the path that a lot of Warsies do and make excuses to get the highest numbers possible. That's why I've done what I could to moderate the numbers without completely throwing science and the events of the episode out the window.
-Mike

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Re: The Enterprise-D and the Lonka Pulsar

Post by Lucky » Thu Feb 02, 2012 1:33 am

Mike DiCenso wrote:That's tempting, but no. The episode's dialog and the visuals all indicate a pulsar, not a stellar black hole. We just have to assume that by the TNG-era, that they've discovered a class of pulsar that is that big, but for some reason is not collapsing into a singularity. It does leave a lot of room open for this being a high-energy pulsar, just one that does not strictly get it's energy from spinning.

The other thing is that I refuse to go down the path that a lot of Warsies do and make excuses to get the highest numbers possible. That's why I've done what I could to moderate the numbers without completely throwing science and the events of the episode out the window.
-Mike
The point I was trying to make was that if the Neutron Star should have been a Black Hole then treating it as one would be done for completeness sake. A black hole might actually have a lower output for all I know.
_____
Shouldn't the beams be coming out of the poles instead of the equator? Don't magnetic fields normally aline with the way an object spins?

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