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View Full Version : Star Trek Photo Torpedo Issue. (Yes, I'm Blushing.)



BigDon
2014-Nov-03, 06:47 PM
Long ago they let slip that a photo torpedo's warhead consisted of six pounds of antimatter.

Back of envelope calc's show a yield of ~ 60 megatons.

Wouldn't lighting off a sixty megaton gamma ray flare inside the orbit of the Moon fry everybody in the facing hemisphere?

Much less a "spread" of four to six?

NEOWatcher
2014-Nov-03, 07:18 PM
Photo torpedo?
I don't know if you are intentionally making a joke. But; to be a spoilsport, it is "photon".
But; I couldn't help to equate that with Photobomb (http://en.wikipedia.org/wiki/Photobombing). Particularly Shatner (http://img.trekmovie.com/images/links/stlv10-shatbomb2.jpg).

Jeff Root
2014-Nov-03, 07:19 PM
"Pounds"?? They used pounds??? Is it in the Star Trek Technical
Manual? That seems to be missing from my bookshelf. I don't
understand where it could be, unless the friend who gave it to
me wanted it back, and I gave it back, and somehow forgot...

Maybe it was "up to six pounds". Since it is loaded with the
antimatter right before launch, it would be really, really, really
really daft not to make it adjustable. Really.

-- Jeff, in Minneapolis

antoniseb
2014-Nov-03, 07:24 PM
I might have this calculated incorrectly, but a sphere with a radius of 4x10^8 meters (moon orbit) would have a surface of about 2x10^17 square meters, which means about one Joule per square meter, which is roughly the energy that square meter gets from the Sun in a millisecond. ... so I'm guessing, no, it wouldn't fry everyone.

NEOWatcher
2014-Nov-03, 07:32 PM
"Pounds"?? They used pounds???
No,


Is it in the Star Trek Technical
Manual?
Yes;

1.5kg per memory alpha's reference (http://en.memory-alpha.org/wiki/Isoton) to the manual (for a standard warhead) for a 64mt blast.

BigDon
2014-Nov-03, 08:11 PM
(Not as grouchy as this might read.)

No, they didn't use pounds, they used kilos.

I erred by both misremembering the weight as 2.5 kilos and by assuming nobody would notice the extra half a pound so I rounded up.

What's a half a pound of antimatter amongst friends? :)

And besides, wouldn't the material of the target vessel disassociating make up the energy difference?

(More :) )

WayneFrancis
2014-Nov-04, 05:04 AM
not knowing the technical specs of a photon torpedo I'd say that the target vessel would have little to do with the explosion. The matter of the actual torpedo would probably be the mass that get annihilated. Much like the nuclear bombs the objective is to get as much of the material in the initial reaction before that reaction blows the rest of it apart and spreads out the energy even further. I'd imagine that they'd have the anti-matter in a magnetic jar and want it to come into contact with its counterpart in a efficient manner. That is my geeky thought on the issue.

novaderrik
2014-Nov-04, 08:45 AM
not knowing the technical specs of a photon torpedo I'd say that the target vessel would have little to do with the explosion. The matter of the actual torpedo would probably be the mass that get annihilated. Much like the nuclear bombs the objective is to get as much of the material in the initial reaction before that reaction blows the rest of it apart and spreads out the energy even further. I'd imagine that they'd have the anti-matter in a magnetic jar and want it to come into contact with its counterpart in a efficient manner. That is my geeky thought on the issue.

the "technical specs" of a photon torpedo varies depending on the plot of the episode..

John Mendenhall
2014-Nov-04, 08:46 AM
For those of you who are hopeless Trekkies, I apologize, but I am going to kick your sacred cow.

So the Enterprise et al. would have to carry several hundred pounds of antimatter to arm photon torpedoes? This is a remarkably dumb idea. ANY leakage will set the whole thing off. IIRC, during the naval battleship era on Earth as many were lost to internal explosions as to enemy action. Mutsu was lost to one at anchor in harbor during WWII. Iowa was lucky to have good isolation procedures when she had the turret explosion. And these are modern events!

If you think it can't happen, review last week's Antare's rocket launch. Launch anomaly? ANOMALY? How about huge screw up?

Noclevername
2014-Nov-04, 11:11 AM
For those of you who are hopeless Trekkies, I apologize, but I am going to kick your sacred cow.

So the Enterprise et al. would have to carry several hundred pounds of antimatter to arm photon torpedoes? This is a remarkably dumb idea. ANY leakage will set the whole thing off.

The Enterprise is powered by antimatter, so they have to carry it anyway. And yes, a "core breach" is the main way starships can die. But it never happens by accident, they have the whole thing swaddled in force fields specifically to prevent leaks.

cjameshuff
2014-Nov-04, 02:03 PM
So the Enterprise et al. would have to carry several hundred pounds of antimatter to arm photon torpedoes? This is a remarkably dumb idea. ANY leakage will set the whole thing off. IIRC, during the naval battleship era on Earth as many were lost to internal explosions as to enemy action. Mutsu was lost to one at anchor in harbor during WWII. Iowa was lucky to have good isolation procedures when she had the turret explosion. And these are modern events!

And yet they continue to carry gun propellant, explosives, and flammable, volatile fluids. Having power and propulsion and something to shoot at the other guy is a bit more important than eliminating any possible cause for an accident.

novaderrik
2014-Nov-04, 06:49 PM
The Enterprise is powered by antimatter, so they have to carry it anyway. And yes, a "core breach" is the main way starships can die. But it never happens by accident, they have the whole thing swaddled in force fields specifically to prevent leaks.


they also have that big door that closes slowly that everyone has to dive dramatically under to get away from the failing reactor core..

Ken G
2014-Nov-04, 07:10 PM
And they need better security in Engineering, dammit...

redshifter
2014-Nov-04, 08:21 PM
And they need better security in Engineering, dammit...

Well, the engineering dudes wear the same color shirts as the security dudes and we all know how that turns out...it's a double whammy!

Ken G
2014-Nov-05, 12:26 AM
Plus none of them know any of the others by sight...

John Mendenhall
2014-Nov-05, 01:01 AM
And yet they continue to carry gun propellant, explosives, and flammable, volatile fluids. Having power and propulsion and something to shoot at the other guy is a bit more important than eliminating any possible cause for an accident.

Good points, but too off topic to explore here.

More on topic, 60 megatons seems low to me. How'd y'all arrive at that figure?

Ken G
2014-Nov-05, 03:38 AM
wolframalpha agrees with 60 mt.

Noclevername
2014-Nov-05, 06:27 AM
http://en.memory-alpha.org/wiki/Photon_torpedo


In 2368, Federation photon torpedo warhead yields had at least 16 preset levels.

The explosive yield (of the type-6 torpedo) could be set to ten different levels. Level 1 was just a fireworks display, level 5 was the standard yield of one kilogram antimatter charge, and level 10 violated strategic arms limitation treaties.

So the amount of antimatter is variable.

George
2014-Nov-05, 02:29 PM
The Level no. used is easily determined from the number of people flying over their consoles.

Grey
2014-Nov-05, 04:13 PM
The Tsar Bomba (http://en.wikipedia.org/wiki/Tsar_Bomba) had a yield of about 50 to 60 megatons, and Wikipedia says that resulted from the conversion of 2.34 to 2.67 kilograms of mass to energy. We'd expect 1.5 kg of antimatter to annihilate with 1.5 kg of matter, producing just a little more energy than that, so that's in the right neighborhood. And descriptions of that explosion can give you an idea of just how much destructive power that is. For example, there was a fireball 5 miles in diameter, and the mushroom cloud was 40 miles high and 60 miles wide. All buildings in a village 34 miles away were destroyed, and any buildings that weren't stone were destroyed even further away than that. You'd be okay if one of these things went off a couple hundred miles away, but you wouldn't want to get much closer than that. Of course, in space, you'd have some different effects. Not as much of a blast without an atmosphere (but a starship would still probably provide plenty of material for the explosion to vaporize...), but lots of radiation.

cjameshuff
2014-Nov-05, 06:25 PM
Another factor is that much of the antimatter-matter reaction output is in the form of neutrinos, so the actual effect would be rather less.

Githyanki
2014-Nov-05, 10:18 PM
Would not a ship's shields protect them?

cjameshuff
2014-Nov-05, 10:38 PM
Wouldn't a tank's armor protect it from bullets and rockets?

MVAgusta1078RR
2014-Nov-06, 10:43 AM
one gram of antimatter annihilating with one gram of matter produces 180 terajoules, the equivalent of 42.96 kilotons of TNT (approximately 3 times the bomb dropped on Hiroshima - and as such enough to power an average city for an extensive amount of time)
http://en.wikipedia.org/wiki/Antimatter_weapon

1000 grams = 1 kilo
1 kilo of antimatter = 43,000 kiltons or 43 megatons
So 3 kilos of antimatter 132 megatons. 6 kilos of antimatter 264 megatons...

Ken G
2014-Nov-06, 11:21 AM
1 kilo of antimatter = 43,000 kiltons or 43 megatons
So 3 kilos of antimatter 132 megatons.But that would be 3 kilos annihilating with 3 kilos, we want 1.5 annihilating with 1.5, so that's why it's about 60 mt.

Solfe
2014-Nov-06, 12:02 PM
Personally, I like Plasma Torpedoes better. They are wildly more powerful, but the ships that carry are super slow.

Someone writing TNG decided that they had a black hole or a singularity inside the "motor" and/or cloaking device. They work as expected - "Mad-libs-plot" style.

So much wacky stuff happens on Romulan ships, that actual combat is infrequent with them during TNG. I think this the reason that all Romulans have reverted to an Imperial period Romanesque stoicism. "Didn't blow up, good day to be paranoid."

kzb
2014-Nov-06, 12:51 PM
As stated above, the yield of a photon torpedo is adjustable. From memory, the antimatter charge is loaded just prior to launch.

It is also stated in the technical manual that it took a lot of research to get antimatter weapons to work efficiently. In the early models, most of it got blasted away before it could annihalate with matter.

The effect of an explosion is much reduced in the vacuum of space. There is nothing to carry the blast wave.

cjameshuff
2014-Nov-06, 01:23 PM
The effect of an explosion is much reduced in the vacuum of space. There is nothing to carry the blast wave.

Which is the rationale for the name, photon torpedoes do their damage by releasing a burst of photons. One of the few bits of Trek technobabble with real world justification.

And as I recall, the reason for photon torpedoes was more than just the vacuum: ordinary navigational deflectors would stop a blast wave component with little trouble.

JustAFriend
2014-Nov-06, 02:10 PM
Wouldn't lighting off a sixty megaton gamma ray flare inside the orbit of the Moon fry everybody in the facing hemisphere?
Much less a "spread" of four to six?

This highlights one of the things I've hated about Trek over the last 30 or so years.
If you look at the original series, the torpedo and phasers were very powerful weapons, with ships facing off over thousands of miles.
As the series went along the ships pulled closer and closer to the point of Pirate-Movie standing broadsides just hundreds of yards away.

It's just dumbed-down filmmaking.

Noclevername
2014-Nov-06, 02:22 PM
Per Memory Alpha:
Starfleet began developing two types of photon torpedoes starting in 2215, with the primary difficulty being the design of the warhead. The first type had the deuterium and antideuterium reactants driven together like in an implosion design nuclear weapon. This torpedo had a maximum range of 750,000 kilometers, as this was the stability limit of the containment field design. It had a low rate of annihilation, and was adequate as a defensive weapon only. The second type, which became operational in 2271 had the reactants mixed together in thousands of small magnetic packets. This increased the rate of annihilation. (pg. 128, 130)
Bold mine.

Noclevername
2014-Nov-06, 02:27 PM
This highlights one of the things I've hated about Trek over the last 30 or so years.
If you look at the original series, the torpedo and phasers were very powerful weapons, with ships facing off over thousands of miles.
As the series went along the ships pulled closer and closer to the point of Pirate-Movie standing broadsides just hundreds of yards away.

It's just dumbed-down filmmaking.


The visuals of ST:TOS were constrained by low budgets. Otherwise they would have made the ships look closer too. The stated distances in TNG were usually on the same order.

The later series also had more precise weapons and better shields, being set a century later than TOS, so they could reasonably use closer weapons. Enterprise, though it was definitely dumbed down filmmaking, had weaker weapons, so they could be used closer.

kzb
2014-Nov-10, 01:23 PM
I don't think we have ever actually seen a photon torpedo being used at anywhere near its maximum yield. The explosion sizes we see on screen could be done with conventional explosives.

That's a free special effects idea, from me to future Star Trek film makers. Let's see some photon torpedos used to devastate a planet.

publiusr
2014-Nov-16, 09:09 PM
Not Photon torps, but we did see a ST Base Delta Zero on DS9's "The Die is Cast"

Noclevername
2014-Nov-17, 12:56 AM
I don't think we have ever actually seen a photon torpedo being used at anywhere near its maximum yield. The explosion sizes we see on screen could be done with conventional explosives.

That's a free special effects idea, from me to future Star Trek film makers. Let's see some photon torpedos used to devastate a planet.

Starfleet is all about restraint. Their torpedoes use just enough and no more. The Klingons and Romulans like to conquer planets, not trash them. Overkill would be counterproductive.