Putting the (pseudo) SCIENCE into SCIENCE FICTION!

I thought it'd be cool to have a forum where we could drop random science factoids that help us to visualize the stuff that goes on in the Traveller universe. Would be better if this wasn't used to dispute current rules or Referee rulings. The point here should be to enhance the game and help players and Refs get their heads around the Scientific/Semi-Scientific/Pseudo-Scientific issues in Traveller. To kick it off, I'll answer something TT asked in the "New Ship" topic. Didn't want to derail another topic with a debate about pseudoscientific stuff, but I thought it'd be a good thing to thrash out somewhere. Anti-Gravity This is a staple not only in Traveller but in pretty much every Science Fiction setting. Writers seem to prefer the idea of folks walking around on a spaceship rather than needing to float around. And rather than have centrifugal forces or other basic ideas keeping feet on the floor it's more popular to have plates in the floor powered by sci-fi magic that create artificial gravity.  From the beginning the Traveller setting has used grav plates to create gravity and negate inertia on board spaceships. As far as I know there has never been any attempt to explain how this is made possible, only that at TL 9 breakthroughs in gravitational theory allow things like this, as well as jump drives, weaponized lasers, and flying cars possible. From memory (maybe Pakkratt or anyone else who still owns a copy of MegaTraveller can weigh in here) The effects of gravplates were described in a little more detail. They mentioned that the range of the gravitational effect was about 2m (again, correct this if this is isn't right). So if you're standing on a grav plate and toss something into the air higher than 2m, it would escape the effect of the grave plate and keep floating upward.... or bounce off the ceiling. This would be the reason why you still need to have magnetic soles if you want to walk on the outside of the ship's hull. Alby said: About the grav plates in the glass, ... yeah I duno. I always imagined that artificial grav plates worked by converting the "weak" gravitational force into a "strong" one like the magnetic force. Tenacious Techhunter said: I’m not clear on what a conversion between atomic forces has to do with whether or not the required plate is transparent. The reason I referred to gravity as a "weak force" is because that's how it's described generally, and not just when talking about atomic forces. It takes an object the mass of the earth to create a force that will accelerate an object by around 10ms^2 (1G). A tiny magnet can accelerate an object faster with far less mass required. You can pick up paperclips with a magnet for example, or a car with a crane and an electromagnet. The effects of gravity extend much farther than magnetic forces do though. The earth will affect that paperclip from hundreds of kilometers away, while the force of the magnet drops off very quickly. The math looks like this: Gravity: F=(Gxm1xm2)/r² Magnetism: F=(m1xm2)/(4πv2r²) My understanding of this stuff is only High School level, and High School was a LONG time ago, but seeing that the distance (r) is multiplied by a bunch of other garbltygoog, that means the force drops of faster with distance. When trying to describe this to my son during out Traveller game, I tried to sell the idea that the "breakthrough" folks made at TL 9 enable them to change the way gravity and space works rather than enabled them to create actual gravity. Because gravplates work diffently to actual gravity. Its a "strong force" in that with only a small amount of mass and energy you can generate a force that normally requires the mass of an entire planet to produce, and effect of that force drops off very sharply compared to actual gravity. To my son I described it working like a magnet's field with poles rather than being a straight line attraction - but that's an Alby thing and not an actual Traveller thing.

Right, but why does that make it necessarily not transparent? How does that explain that transparency and atomic force conversion are mutually exclusive?

Oh none of that has anything to do with the transparency of it. My thinking was that if the grav plate was in the ceiling pushing downward rather than in the floor pulling downward. Then you could have whatever you wanted on the floor. It can be glass or transperisteel and it wouldn't matter because it's not a grav plate. If my grammar was better that would have been clearer in what I said. The point I was trying to make was that the floor doesn't need to be a grav plate.

STARS Stellar class is something that I've always had trouble getting my head around. Just in case anyone else needed help visualizing the stellar descriptions in world data, here's a handy poster: So the first couple of letters used to describe a star represent it's temperature and luminosity. The last roman numeral represents it's size. 0 or Ia + for hypergiants I stars for supergiants II for bright giants III for regular giants IV for sub-giants V for main-sequence stars sd for sub-dwarfs D for white dwarfs. So our sun Sol is a G2V star. A yellow, regular Joe main sequence star. Fun( ish ) fact: between 70% - 80% of the stars in our part of the galaxy are M class main sequence stars - or red dwarfs. Red Dwarfs are so dim that you can't see them from Earth with the naked eye. The Habitable Zone of a red dwarf star is closer to the star than mercury is to our sun. This makes it highly likely that any planet within the zone is land locked with one face always facing toward the star. If a planet was actually a satellite orbiting a gas giant rather than in orbit around the star alone then it could have a regular day/night cycle. Red Dwarf stars are also very erratic. So a sun spot could cause a planet to freeze over for months, while one of it's regular flares would bake it and bombard it with radiation. Life on these worlds would be very different to life on earth. Plants could be black to absorb as much of the dim light as possible. If the world is tidally locked then life would need to adapt, probably preferring to stay underwater or under the ground. A world could be outside of the regular habitable zone, with most of it's heat coming from a greenhouse effect rather than from sunlight. Such a word would be very dark. Life may be based on chemosynthesis rather than photosynthesis. Most of the worlds in the Spinward Marches orbit red dwarf stars. The world we are currently on, Rhylanor, as well as the worlds on the way toward Regina, Tureded, K'Kirka, are all orbiting red dwarfs.

Question, Would fat provide an armor benefit against laser's?

Is that .... the fat of someone else or your own body fat? I did see an interesting video once of a marshmallow being toasted with a laser. They toasted a second one, but on the second one they used a permanent marker pen to put a small black dot on the surface. As the laser traced across the white surface of the marshmallow it toasted it okay, but as soon as the beam hit the black dot the whole thing burst into flames. Something about absorbing the energy rather than reflecting it? So maybe lightly colored fat would provide better protection than darker fat? Maybe this is the thinking behind stormtrooper armour in Star Wars? Although, I'm struggling to remember a single time when stormtrooper armour actually worked.

PLASMA and FUSION GUNS! ( disclaimer: this rant is only semi-science. It's mostly based on my poor recollection high-school lvl science  and Traveller lore. I still think it's stuff worth thinking about however. ) I wanted to make a few comments about plasma and fusion weapons because 1) we have them, and 2) there seems to be a bit of fog over what they are and how they work. First thing to straighten out is that plasma weapons fire hydrogen nuclei at their targets. Not shells that contain plasma (as someone said a while back) and not some kind of gooey, glowing sci-fi space laser looking stuff. In Traveller plasma weapons are pretty well defined.  A laser ignition system in the weapon itself heats hydrogen fuel to a plasma state. The plasma is contained in the ignition chamber briefly and is then released through a magnetically focused field along the weapon’s barrel. The high initial velocity plasma jet is 2 centimeters in diameter, but it begins to dissipate immediately. Plasma is pretty much what the surface of the Sun is made out of. So to understand hydrogen plasma, imagine a hydrogen atom with it's single proton and a single electron in orbit around it. At regular temperatures this is a gas. If it is headed to about 5000C it becomes so energized that it sheds it's electron. Remembering that gas is floaty and gassy because the gas atoms/molecules are bouncing around and want to stay away from each other. Now imagine a gun that, instead of firing a bullet fires gas! Now imagine that that gas is even more energized, and the atoms/molecules are even more eager to stay away from each other! Normally speaking, a cloud of plasma makes a terrible "bullet" to fire out of a gun. So by necessity there is some kind of Sci-Fi, "gravitational field" magic that stops the plasma from simply dispersing. This sci-fi magic keeps the plasma in a coherent bolt and fires it out toward a target. Cool. Now ... fusion guns (this is where I start to rant) The FGMP-14 differs only in that it contains the plasma slightly longer until a fusion reaction begins to take place. The weapon is somewhat more powerful than a plasma gun This kind of reaction happens within the heart of our sun. It's when two hydrogen nuclei fuse to become a helium nuclei. It requires insane temperatures and pressure and gives of spare neutrons in the process. The neutrons are emitted in the forms of x-rays and gamma rays.  In previous versions of traveller, Fusions didn't bathe the entire area in radiation when they were fired. The assumption seemed to be that whatever Sci-Fi magic keeps plasma/fusing hydrogen bolts together also keeps the neutrons together in the same bolt. But Mongoose Traveller (and Mongoose only as far as I know) has decided to make Fusion Guns do this: Those without radiation protection who are nearby when a FGMP is fired will suffer a lethal dose of radiation – each firing of an FGMP emits 2d6 20 rads, which will affect everyone within the immediate vicinity. This is horrible for a number of reasons. First of all, all steel in the area immediately becomes irradiated. Steel becomes cobolt 35 (?) and such with a half life of about 5 years. You can't just clean that up. It stays radioactive for years. Second, 2d6x20 rads means that even if you and your friends have battledress on, you've got a 1 in 12 chance of receiving a dose of radiation ("battle armour" reduces rads by 200). Those are rads that, if you don't medicate immediately, never go away . Those in less than battledress will just get cooked. And this is for everyone nearby.  Yeah you may blow that guy away, but that's little consolation when you're gums start bleeding and your hair starts falling out. So you're ship is now radioactive, and you and your friends get irradiated each time you pull the trigger. Arguably the worst weapon ever. IC Kayleb has had a lengthy discussion with Cpt. Crow about going with plasma guns or other weapons instead of fusion guns. It's the main reason our G-Carriers don't have them.

I think you are talking about <a href="https://en.wikipedia.org/wiki/Cobalt-60" rel="nofollow">https://en.wikipedia.org/wiki/Cobalt-60</a> and what it does mention of iron being eventually activated into cobalt seems to be over time within a nuclear reactor. Weather or not shooting a gun that gives off a single pulse of radiation would be enough to convert enough of the FE into cobalt to give off hazardous amounts of radiation would depend on the effect of 40-240 (at maximum) RADS. That said the effect on unprotected people is undeniably sucky, a dose of 240 would give 2d6 burn damage. an average dose (140 RADS) would give 1d6 burn damage. Dunno if armor would protect against the burn damage, but anything over 150 cumulative rads does permanent endurance damage, which inevitably, would kill you with enough uses unless you somehow got 240 rad protection. RAW, this gun is effectively useless and shouldn't have made it past play testing, as MAN PORTABLE it may be, but MAN USEABLE it is not. The TL17 rifle variants do however mention gravic shielding that protections the user from the radiation (only applying it to those in personal range in front of the firerer). This however is not mentioned with the FGMP, and it says only "immediate vicinity" without giving a precise range or if it protects the use or not. In second edition mongoose traveller the RAD protection of battle dress has been increased to 245, right next to our sweet spot of 240 that we need for full protection from a FGMP. (which hasn't changed in 2nd edition). It can therefor be assumed that because it says in multiple places that Battle dress and plasma/fusion guns were meant to be used in conjunction, that said battle dress would be sufficient protection from the radiation produced from the weapon. It seems that their oversight was corrected in 2nd edition by buffing the resistible RADS so that a battle dress user would not take RAD damage from their own weapon. This makes sense given their cannonotical use together. This certainly could be a valid point in favor of implementing a house rule the buffs the RAD protection of battle dress.

... yup 2nd ed does fix up a few things. Also did some silly things. Would love to find a happy island in between 1st and 2nd ed somewhere. ((edit: mind you, I get the feeling that the radiation effect of the weapon is a game balance thing. It's there to force players to think twice before using it. Letting players have supa dupa guns with no drawback or game balancing feature would be bad. Almost as bad as an unusable radiation spewing weapon maybe?)) For now I'd rather stick with the old PGMP-14. It doesn't fry your friends and neighbors like the FGMP-15 does and the ROF of the PGMP-14 is higher (6 vs 4). PGMP-14 is also 1/4 the price of the FGMP-14 too. I'd rather have a posse of 4 guys with PGMP-14s than one guy with an FGMP-15!

It was primarily on the basis of the radiation dispersal that Charoux ordered RV to immediately disable the FGMP... which he apparently had not done. Upon my prior reading, I had naively assumed that the radiation would have been dispersed within the lines of a 90 degree cone, or “out from the center of the target”, or both, rather than “omnidirectionally from the end of the barrel”. I haven’t given it a serious read since then, either; hence the order. In theory, every Imperial Naval Vessel, and every local System and Planetary Militia worth a damn, is going to have sensors that immediately (within the limits of the speed of light, perhaps, or maybe not) sound an alarm that unsanctioned nuclear weapons fire has been performed; whether or not this is genuinely the case, Charoux would simply assume so, if only because it’s the sort of technology an adversary would develop and simply not inform their allies about. Assuming no knowledge of RV’s betrayal, Charoux would insist that he not keep the FGMP, simply because it provides no benefit to the success of the decoy mission; it can’t be fired without drawing so much attention that the authorities would put two and two together, and identify the Star Hunter, thus defeating the whole point of the exercise to begin with. Instead, Charoux would insist that he gear up from the Company Armory.

Even without the radiation, firing an FGMP inside a ship is MADNESS! At least in classic Traveller it's an area effect. You don't use an FGMP on someone in the same room with you for the same reason you don't throw 200Kg &nbsp;of TNT at them.

Alby, I have a small issue with your conclusions here: Me: Small detail: the minute RV fires that thing for any reason, all the Impy sensors will go off, and the mission will fail, because they’ll associate the known ship type with the firing of the weapon we are known to be carrying Alby: Pretty sure that's not true. Starship hulls block 500 rads. Fusion gun emits up to 240. The ships fusion reactor probably emits more radiation out into space than firing an FGMP inside would. Just say'n. Better reasons for RV to not have FGMPs are probably that he's not qualified to use one, It's a dangerous weapon that emits enough radiation to kill us all if he ever used it, and it's as legal as a nuclear missile is. Plenty of good reasons to be leaving the thing alone This is rather like saying, “If you aren’t within damage-inducing range of a nuke, you can’t detect it.”. I could correct the math of that statement to be more correct, but you see my point; nukes can be detected well outside the range from which they are inducing player-relevant “gameplay rads”. I think an FGMP would, too, for the same reasons.

Tenacious Techhunter said: This is rather like saying, “If you aren’t within damage-inducing range of a nuke, you can’t detect it.”. I could correct the math of that statement to be more correct, but you see my point; nukes can be detected well outside the range from which they are inducing player-relevant “gameplay rads”. I think an FGMP would, too, for the same reasons. You can detect things by sound (vibration), heat, light (photons) or radiation &nbsp;and possibly in traveller by its gravitational pull. In space, you have no matter to transmit the vibrations, and the ships hull would block the light and the radiation, assuming it wasn't actually exploded by the weapon and the heat would be entirely too non specific to really tell what it could be. There isnt so far that I know any magical "someone used a device that generates radiation" sensor that wouldn't require one of those things to physically be perceived by the sensor. Sensors work by things HITTING them. your eyes work by light hitting them, your nose works by chemicals hitting receptors, your sense of touch works by vibrations triggering nerves. Its the same with mechanical sensors. IF the ships hull blocks 500 rads of radiation, and the weapon only produces 240, it would be the same as turning on a flashlight in a bunker a mile under the earth. No one could possibly know you've done it. A nuke would work on the same exact principal except its usually alot more difficult to build something that could contain the light, heat, radiation and vibration of a nuke. Adendem: Its possible a psion could detect if a nuke was used if they used E.S.P. But I am sure the Imperium would never be caught doing su... *gets dragged off*

Koushiro, the problem here is the gameplay mechanic vs. science... Scientifically speaking, radiation shielding doesn’t work 100%, because of how much space there is between atoms; it only blocks enough of the radiation to not matter so much (but still lets enough in that you should keep track of it, to limit your cumulative exposure). The gameplay mechanic doesn’t work that way; if the ship’s hull blocks more radiation than is generated, then none gets through to your character sheet, for the sake of not doing math all the time. But, in the real world, there are still plenty of ways to detect a nuke at far enough distance away that you won’t be taking damage from it, radiation or otherwise. In the real world, so long as the emitted radiation is above the noise-floor for sensors (rather than up to the damaging accumulation level for living things , which would be higher ), it should be detectable.&nbsp;By that same token, so long as the emitted radiation is above the gameplay-value noise-floor for sensors (rather than the gameplay-value noise-floor for living things ), it should be detectable. In principle, there really aught to be a table of some sort covering this difference between the blocking of radiation for sensing purposes vs. the blocking of radiation for concealment purposes; however, no doubt, not even Vlen Beckett would coat his ship in such a way as to conceal a nuclear explosion , because trying to set one off inside a ship is insane . Maybe the ship’s power plant specifically , but not the entire ship ... It’s hard to find a case where that would make sense; maybe a cargo hauler that hauls radioactives illicitly? I’m not even sure if interstellar navies have a use for this sort of thing...

Jim M. said: Even without the radiation, firing an FGMP inside a ship is MADNESS! At least in classic Traveller it's an area effect. You don't use an FGMP on someone in the same room with you for the same reason you don't throw 200Kg &nbsp;of TNT at them. Ugh ... don't ... no ... don't go there .... Mongoose Traveller changed Plasma and Fusion guns so that they go "pew-Pew-pew" instead of "F'CHOOOooooommm!!!" As cool as rapid fire energy weapons are, it was a mistake. A mistake they fixed in the 2nd ed of Mongoose Traveller by the way. 2nd ed PGMPs and FGMPs have gone back to "F'CHOOOooooommm!!!" Even as a matter of sense, anything that does that much damage would also do damage to anything in a radius from the point of impact even if it's just from the target matter exploding. Would rant on, but I need to go take a nap.

Tenacious Techhunter said: Koushiro, the problem here is the gameplay mechanic vs. science... Scientifically speaking, radiation shielding doesn’t work 100%, because of how much space there is between atoms; it only blocks enough of the radiation to not matter so much (but still lets enough in that you should keep track of it, to limit your cumulative exposure). The gameplay mechanic doesn’t work that way; if the ship’s hull blocks more radiation than is generated, then none gets through to your character sheet, for the sake of not doing math all the time. But, in the real world, there are still plenty of ways to detect a nuke at far enough distance away that you won’t be taking damage from it, radiation or otherwise. In the real world, so long as the emitted radiation is above the noise-floor for sensors (rather than up to the damaging accumulation level for living things , which would be higher ), it should be detectable.&nbsp;By that same token, so long as the emitted radiation is above the gameplay-value noise-floor for sensors (rather than the gameplay-value noise-floor for living things ), it should be detectable. In principle, there really aught to be a table of some sort covering this difference between the blocking of radiation for sensing purposes vs. the blocking of radiation for concealment purposes; however, no doubt, not even Vlen Beckett would coat his ship in such a way as to conceal a nuclear explosion , because trying to set one off inside a ship is insane . Maybe the ship’s power plant specifically , but not the entire ship ... It’s hard to find a case where that would make sense; maybe a cargo hauler that hauls radioactives illicitly? I’m not even sure if interstellar navies have a use for this sort of thing... Space also has a lot of background radiation, it would be highly doubtful that the small amount that managed to pass through the ship's hull would be noticeable at all above it. (like trying to detect tears cried into the ocean). The further away you are from the detonation, the fewer and fewer particles there would be to hit your sensor. and distances are massive in space, to the point where there might be only one or none that actually hit the sensor.

Yes, yes, inverse-square law and all that, but not all radiation is the same. You would probably look for neutron radiation emissions with a particular distribution of velocity; with the right filters, the background stuff could be filtered out; rules-wise, unfortunately, it depends a great deal on interpretation of the fluff and the GM deciding things.

Space also has a lot of background radiation, it would be highly doubtful that the small amount that managed to pass through the ship's hull would be noticeable at all above it. (like trying to detect tears cried into the ocean). The further away you are from the detonation, the fewer and fewer particles there would be to hit your sensor. and distances are massive in space, to the point where there might be only one or none that actually hit the sensor. This. ↑ Starship hulls are specifically designed to stop stellar and cosmic radiation cold. It would take twice as much radiation than the FGMP puts out (in it's general area of rad hurt) to get through the hull. If a sensor detects radiation, how many rads is it detecting? less than zero. Even if some radiation did get through the hull, so much of it would be blocked and distorted that any sensor operator would be jumping to conclusions to believe that it was an FGMP and not a burp in background radiation, or the ships fusion power plant flatulating, or some other radioactive phenomena. I think we're safe if RV pulls the trigger on that thing. ... safe from imperial sensor operators at least.

Starship hulls are designed to stop radiation from meaningfully interacting with living beings ; if they offer only as much protection as Earth does, which is not perfect defense against radiation, they are sufficient at doing their job. I do not read “reducing Rads to 0” as having any intended meaning for sensors. I can well understand the argument that, taking the rules verbatim, even when they are clearly lacking, is a wise choice; but I reject the argument that, just because Rads have been reduced to 0 in terms of causing meaningful damage to a player, that they are entirely blocked ; in the real world, it doesn’t work anything like that . Which is why even a Geiger Counter, and not even some fancy Sci-Fi gear, can read trivially harmless levels of radiation in addition to dangerous ones.

Even if some radiation did get through the hull, so much of it would be blocked and distorted that any sensor operator would be jumping to conclusions to believe that it was an FGMP and not a burp in background radiation, or the ships fusion power plant flatulating, or some other radioactive phenomena. I think we're safe if RV pulls the trigger on that thing. ... safe from imperial sensor operators at least .The point is, enough radiation would be blocked to prevent it from being detected as an FGMP blast.

Alby, the level of reduction required to prevent detection by sensors is not even remotely on the same scale as what is required to prevent injury to living things. It is just plain not realistic, at all . Now, if we’re going with the existing rule for the sake of it being an existing rule, that’s fine, but it just doesn’t even remotely match the science. I really don’t think a ship’s hull, radiation shielding or not, is going to cut it in terms of preventing detection.

Tenacious Techhunter said: Alby, the level of reduction required to prevent detection by sensors is not even remotely on the same scale as what is required to prevent injury to living things. It is just plain not realistic, at all . Now, if we’re going with the existing rule for the sake of it being an existing rule, that’s fine, but it just doesn’t even remotely match the science. I really don’t think a ship’s hull, radiation shielding or not, is going to cut it in terms of preventing detection. If you want to use "its science" as your defense, you should therefore use the math. Since a Rad is a measurable amount of energy absorbed per kilogram (0.01 Joules), and radioactive particles generally have a defined amount of energy (a gamma ray has 2×10 −14 Joules or 0.00000000000002 Joules), you could therefor calculate the amount of particles given off (1.3 feet of lead reduces gamma radiation by a factor of a billion, and ships are purposefully shielded to protect against radiation, so lets be conservative and say whatever material it is made of reduces the effect by a hundred thousand, starting from 240 rads, leaving us with 0.0024 Rads, or 0.000024 Joules of energy), leaving us with (1,200,000,000 rays absorbed by a typical man sized object at close range (lets say 5 feet)) and then use the inverse square law to determine how many particles exactly at what distance would hit a sensor detection device based on the size of the sensor. At a distance of 4,185,104,986 feet (100 diameters of an earth sized planet) a Man Sized sensor (since we started with a man sized measurement of rads) would only encounter 3.42e-23 joules of particles, which is many orders of magnitude smaller than even 1 gamma ray. (2.00e-14 joules) Meaning at that distance and that size of sensor, the likely hood of even one ray hitting it would be 1.71e-7% (or 0.000000171%). Lets dial that back and consider a distance of 5,280,000 feet, or 1000 miles, which is peanuts in terms of distances in space. that would give us 2.15e-17, which is still only yields 0.1075% chance of even one particle striking it. So what is the distance that gives a 100% chance of one particle striking a man sized sensor? 33 miles. I don't proclaim to be an expert on the subject and my numbers may be off (I welcome corrections if they are), but I think with a little research you can see that, unless you had a mega huge sensor that was close up, you wouldn't really detect a meaningful amount of particles. And I would say that the chance of the Imperium setting up massive detection satellites on ever single one of its worlds on the off chance that someone uses an FGMP inside a space ship would be slim to none. Scientific possiblity is not economic feasibility. Sure they could easily make detection sensors for large overt uses of nuclear weapons, but there comes a point where the cost of the sensor out weighs the benefit. And an FGMP is less powerful than standard ship lasers so I have a feeling they wouldn't be creating giant sensor arrays to detect their use. in space. inside of a radiation shielded hull. I cannot be sure, and am just adding this here, but if the way rads are calculated means a 240 rad dose to a 100 kg (220 pound) man would thus be 100kg x 0.01 Joules, then you could thusly multiply all the results by 100 to adjust for this (meaning 100 particles would strike at 33 miles etc)

Thanks Koushiro. That's pretty much the point TT. Like I said twice earlier, even if a tiny amount of radiation did penetrate the hull - we're talking about a fraction of a rad here - it's hardly enough for " all the Impy sensors will go off "&nbsp; The ship's power plant and maneuver drive would easily give off a more prominent signature than the firing of an FGMP from within the hull. I'm really hoping you can accept this point without further banter. Game mechanics, Science, and plain ol' common sense seem to all be in agreement here. And why are we measuring radiation in Rads and not Greys?

Alby said: And why are we measuring radiation in Rads and not Greys? Public conscious type thing I'm guessing? I only really heard about Greys a few years ago myself, from randomly slogging through Wikipedia. (probably Fallout triggering some desire to research radiation type stuff). Even then, I kind of forgot about them until I read the article again.

I avoided the “respect the math” argument mostly because I don’t think it carries any weight with this group; I’d be more than happy to discuss the math with someone who respects that argument, though: The first problem is that “game rads” don’t correspond to “scientific rads”; based on the application, they more closely resemble “Grays”; the key difference being that “Grays” implies “the part of the radiation that meaningfully interacts with the subject being tested”. Unfortunately, it’s really hard to use the base book’s chart for anything useful; it puts “hair loss” before “internal bleeding”, even though the opposite can be true. Obviously, they put “hair loss” before “internal bleeding” for gameplay purposes, so that improperly equipped players would have prior warning that they were in trouble. :P Honestly, the whole section has to be thrown out and rewritten, and doesn’t really work for constructing a logical argument; we have to operate on a completely different scale to have a useful basis for anything. Also relevant is the “Sievert”, a unit that is important for real-world issues, where continuous low-dose exposure matters over time; a factor which in-game medicine makes largely irrelevant. The destructive particle of choice for an FGMP is going to be the neutron; it’s the non-EM particle that offers the most penetration through armor, and does the most damage; additionally, “Gamma Rays” are more useful as a laser, since they’re Electromagnetic Waves (and, thus, have all the related weaknesses of weaponized light); it would make more sense to channel the fusion explosion for the purposes of making a bomb-pumped laser than to have the fusion explosion emit Gamma Rays. According to a NASA experiment on the contribution of neutrons to the Cosmic Background Radiation ( <a href="https://en.wikiversity.org/wiki/Radiation_astronom" rel="nofollow">https://en.wikiversity.org/wiki/Radiation_astronom</a>... ); they detected 3.9 µSieverts per hour with a small (grape-fruit sized?) ball-shaped instrument; this is equivalent to 3.9x10^-5 actual rads per hour. In neutron-Joules, that’s&nbsp;6.53x10^-33 neutron-Joules per hour. So the bar for detection here is pretty damn low . But yes, we do need at least one particle to detect, and more like a few, just to be sure; but, so long as the combination of the number of the neutrons, and the velocity of the neutrons, is anomalous, we’ve got ourselves a detector.

Tenacious Techhunter said: I avoided the “respect the math” argument mostly because I don’t think it carries any weight with this group; I’d be more than happy to discuss the math with someone who respects that argument, though: The first problem is that “game rads” don’t correspond to “scientific rads”; based on the application, they more closely resemble “Grays”; the key difference being that “Grays” implies “the part of the radiation that meaningfully interacts with the subject being tested”. Unfortunately, it’s really hard to use the base book’s chart for anything useful; it puts “hair loss” before “internal bleeding”, even though the opposite can be true. Obviously, they put “hair loss” before “internal bleeding” for gameplay purposes, so that improperly equipped players would have prior warning that they were in trouble. :P Honestly, the whole section has to be thrown out and rewritten, and doesn’t really work for constructing a logical argument; we have to operate on a completely different scale to have a useful basis for anything. Also relevant is the “Sievert”, a unit that is important for real-world issues, where continuous low-dose exposure matters over time; a factor which in-game medicine makes largely irrelevant. The destructive particle of choice for an FGMP is going to be the neutron; it’s the non-EM particle that offers the most penetration through armor, and does the most damage; additionally, “Gamma Rays” are more useful as a laser, since they’re Electromagnetic Waves (and, thus, have all the related weaknesses of weaponized light); it would make more sense to channel the fusion explosion for the purposes of making a bomb-pumped laser than to have the fusion explosion emit Gamma Rays. According to a NASA experiment on the contribution of neutrons to the Cosmic Background Radiation ( <a href="https://en.wikiversity.org/wiki/Radiation_astronom" rel="nofollow">https://en.wikiversity.org/wiki/Radiation_astronom</a>... ); they detected 3.9 µSieverts per hour with a small (grape-fruit sized?) ball-shaped instrument; this is equivalent to 3.9x10^-5 actual rads per hour. In neutron-Joules, that’s&nbsp;6.53x10^-33 neutron-Joules per hour. So the bar for detection here is pretty damn low . But yes, we do need at least one particle to detect, and more like a few, just to be sure; but, so long as the combination of the number of the neutrons, and the velocity of the neutrons, is anomalous, we’ve got ourselves a detector. It would also be relevant to mention that the game only gives a blanket protection of RAD reduction, where as various different types of radiation are more susceptible to being stopped by different material, for instance neutron radiation isn't much affected by lead, but hydrocarbons and water tend to stop it. And as well, because of the Inverse Square law, the rads from any given source would change over distance, where no such game mechanic is given for such things. This game, largely tries to simplify things to allow us to concentrate on the fun bits rather than the maths and calculus even though it does take away a lot from the reality of things. Given that I have not come across any lore or rules concerning the imperium monitoring space for use of nuclear weapons (of any size) I would be interested to know if you had?

Given that I have not come across any lore or rules concerning the imperium monitoring space for use of nuclear weapons (of any size) I would be interested to know if you had? I'm sure he'll pull something out of his arse. The whole point is kinda moot anyway. If the Star Hunter was flying off as some kind of decoy, we actually want Imperial forces to detect it. So give that thing to RV and let him rapid fire it out the window. That should get the Imperial patrol ships on his tail!

Meh, I’ve lost much motivation to continue defending my point; which is not to say that I cave, just that I have nothing good to fight with; Traveller just runs out of science too often to build a case. But here’s some fun detailed bits on Radiation, thanks to Atomic Rockets:&nbsp; <a href="http://www.projectrho.com/public_html/rocket/radia" rel="nofollow">http://www.projectrho.com/public_html/rocket/radia</a>... A few things to note, though; the Mongoose rule books peg ship sensors at a fixed range, and don’t mention much about other ranges, and those ranges tend to be fairly short, like within a few Earth diameters. So, as per the rules, my points are moot anyway, even if NASA could build such a sensor today . :P (Seriously, can we get a harder Sci Fi RPG?) Also, unless I’m mistaken, we’ve been misusing the sensor suite bonus... it should only apply when countering ECM; maybe also radiation sources, but that’s Bob’s call.

Also, unless I’m mistaken, we’ve been misusing the sensor suite bonus... I'm pretty sure you're right about that. I lost a discussion with Wolfen about this. We seem to be adding that bonus onto everything including comm checks. It does state pretty specifically on p108 of the Core Rulebook: The Dice Modifier applies to jamming and counterjamming attempts. I raised this issue a while back in the MAKING SENSE OF SENSORS topic. Having stealth on your ship or running quiet provides you with a - DM to being spotted by sensors (-4 and -2) but there is no mention of an actual sensor roll anywhere. There is a sensor roll to determine encounter range on p139. So I guess it could be talking about that? If that's the case then both you and whatever you are encountering would need to make a roll. If you're being sneaky then they would subtract your stealth sneakiness DM from their roll. If someone rolls an encounter range greater than the other then the one who rolled the greater range would have the element of surprise. That's not really in the rules. In the rules its just one roll. Its the closest thing I can think of to something that makes sense though. Otherwise you've really got to ask what the point of spending MCRs worth of stealth is.&nbsp; It would also make sense to be adding the sensor suite DM to this roll because you'd think that better sensors would be an advantage against stealth technology. Rules are kinda vague.

Military Sensors operators can make ECM rolls to jam Sensors and Comms; the bonus is to buy off the penalty from that roll.

Because I'm a child <a href="https://www.youtube.com/watch?v=FcArnepkhv0" rel="nofollow">https://www.youtube.com/watch?v=FcArnepkhv0</a>

Koushiro said: Because I'm a child <a href="https://www.youtube.com/watch?v=FcArnepkhv0" rel="nofollow">https://www.youtube.com/watch?v=FcArnepkhv0</a> Lol! Gosh that makes me feel old! I just remember why I lost my whine to Wolfen about this issue. There are items and add-ons in the High Guard supplement that do give a bonus to detection. This is from page 45 of High Guard: Improved Signal Processing: (TL 11, 1 ton , MCr 4) Signal processing consists of extremely specialised computers and software to improve the quality and likelihood of detection. Improved signal processing provides a +2 DM to sensor tasks and improves of range band of “full” and “limited” by 1 for radar, lidar, densitometer, thermal and visual sensors. However, this comes at a cost of increased vulnerability to jamming, with all jamming DMs doubled. Enhanced Signal Processing: (TL 13, 2 tons, MCr 8) As for Improved Signal processing except that it has a +4 DM, the range band increase is two and the susceptibility to jamming has been overcome We have that second option on the Athena. The whole sensor show on board the Athena is: Countermeasure suite (+4 for electronic warfare) Enhanced Signal Processing (+4 on sensor rolls) Jump Filters (+4 to track jumps) Note that we don't have the Military Countermeasure Suite. That would be cool (+6 DM - raspberry flavoured ) but takes up 20dtons. So if there was ever a sneaky ship out there applying a -4 DM to our sensor operators check to detect them because of their ship's Stealth add-on we effectively negate it with our +4 DM to sensor checks thanks to Improved Sig Processing. I'm still not seeing anything that says the DM applies to Comm checks. Maybe to comm checks to resist being jammed, but not to do things like establish comms over long distances or anything like that.

Yeah, now that you’ve posted Enhanced Signal Processing, I remember specifically asking for that; I just couldn’t find it anywhere, so I thought I was wrong. Comms checks are usually only to establish (or reestablish) a Comms link; you don’t usually do it for maintaining a Comms check, unless circumstances change significantly (and I would argue that the additional penalties should apply to your first roll, which should only be re-rolled if it then fails). I could be wrong about Comms ECM being the same as Sensors ECM, but the whole matter is confused by Sensors ECM being part of the Sensors package, rather than as a separate ECM station (which it probably aught to be).

ORBIT Air/Raft: An open-topped vehicle supported by anti-gravity technology. Air/rafts can even reach orbit but passengers at that altitude must wear vacc suits. They are ubiquitous, remarkably reliable and flexible vehicles. Grav Floater: A grav floater is a forerunner of the grav belt, a platform upon which a single person can stand and be carried along. It cannot achieve any great speed but can, like an air/raft, achieve any altitude up to orbit . Back when I started playing Traveller ( age 13 ) we would often float our air/raft up to orbit where our ship would be waiting. Wasn't until much later that this made less sense. My definition of "orbit" was pretty simple at 13. It just meant "space". The magical place above the sky where astronauts, space shuttles and satellites float around. Turns out that "Orbit" is not really an "altitude". Well it sort of is. It's both an altitude and a velocity. Too slow and you crash back down to earth. Too fast and you fly off into space. The mean velocity required to maintain a close orbit around an earth sized planet is about 8km/second. That's about 30,000km/h (about 18000mph). That's a bit of a problem for our air/raft. Even if you add the earth's rotational speed ( about 1600km/h - around 1000mph ) our air/raft is going to have trouble matching the velocity of our ship in orbit. Like trying to park a car in a garage that is travelling at several miles per second! In Traveller this isn't too much of a problem. Unlike real life ships that need to burn fuel a Traveller&trade; ship with a maneuver drive can hover at an "orbit" altitude by accelerating away from the planet with an acceleration equal to the acceleration due to gravity (1G..ish). That way our air raft can park in it's hanger quite easily. But if the ship was powered down or pilot-less and in an actual orbit then the we have the problems already stated above.. .. unless ... An air/raft can continue to accelerate once it leaves the drag created by a planet's atmosphere. If the maximum speed of an air/raft is capped due to drag then It could exceed that max speed once it's above the sky. If an air/raft has a regular car like acceleration of 2 m/s^2 then it'd take about two days to (calculation fail) about 46 minutes to accelerate up to the speed required to maintain an orbit. Here's a cool little vid that I thought could help us visualise what's going on when we fly our ships around in a Traveller game: Cute Orbital Dynamics Video This image is cool to. Shows the height of different orbits. Handy to keep in mind if we wanted our ship in geostationary orbit in order to rain down ortillary death on ground targets. We'd either need to be very very far away or be hovering. Cool Image of Orbit Altitudes.

"We're on an express elevator to hell - going down! " RIP Bill. With our G-Carrier about to make a drop, I thought I'd be fun to geek out on how long it could take for it to reach the ground. I thought I saw somewhere in the rules that a bounce from orbit to the ground took 20 minutes. Can't find that anywhere though. So I thought I'd scratch around outside Traveller for an answer. From orbit to touch down is a 30 minute trip for the space shuttle. This may not be as relevant for us because in Traveller we don't have to use atmospheric friction against the hull for brakes. Grav drives would be doing most of that work. Seemed like a good ball park number though.&nbsp; Lets just say we're above an earth sized planet that, for some weird reason has no atmosphere. If we were dropping a G-Carrier from a geostationary position in a&nbsp; 300km "low orbit" altitude - not actually in an orbit, just hovering there -&nbsp; and assume that it's adding it's own thrust to the acceleration due to gravity, then it would take then it would take ( with deceleration: Time=2 x Square Root of (distance/acceleration ) about 5 minutes (?). That's ignoring atmosphere however. To figure out the time to ground with an atmosphere we'd need to know our G-Carrier's mass, surface area and drag coefficient and the density of the air it was falling through to be able to calculate her terminal velocity. We don't know any of that stuff, plus things like density vary as you go down. Too much MATH! I was reading somewhere that the terminal velocity of a car is about 150km/h (about 90mph). The formula for terminal velocity includes mass, and the mass of our G carrier is a fair bit heavier than a regular car. But it's drag would be greater too ... I guess? So let's just imagine the terminal velocity of our G-Carrier was x3 or even x4 that of a car. That's still less than the vehicles maximum speed of 640km/h. So let's just use that. Logically gravity would accelerate you to a speed faster than this until you hit the denser part of the atmosphere, but let's just pretend for a moment that it would all even out and we have a stead 640km/hour ride down from our ship 300km above the ground. The trip would take us about 30 mins (28 if you want to be exact). So the Express Elevator to Hell would take somewhere between 5 mins and 30 mins. I think at this point 20mins is looking like a reasonable number?

The speed with which a Space-Shuttle lands is hard lower-limit for anything but Shuttles and Starships; the Space-Shuttle is literally slowing down the least possible amount on the way down; therefore, slowing down faster would mean flying at a slower speed the rest of the way. I would argue that a G-Carrier or Air-Raft has to negate its orbital velocity enough to reach its maximum atmospheric limit before it can drop; G-Carriers and Air-Rafts ( especially Air-Rafts) aren’t designed for reentry.&nbsp;Of course, this is a conservative maximum limit; there’s probably some room to “cut the corner” atmospherically, particularly with an experienced Grav-Craft Pilot; so long as the thing stays within reasonable thermal tolerances, it can drop in spite of its speed. Gameplay-wise, though, that’s a tough balance to implement. There probably aught to be a disposable ablative shell for G-Carriers making battlefield atmospheric reentries... By the way, I like how that video showed a Bi-Elliptical Transfer before the more wasteful, but faster, Hohmann Transfer; but, with plenty of fuel to spare, only the poorest planets will be launching things with Bi-Elliptical Transfers, and no Starship pilot would waste their time with one (except, perhaps, bulk cargo-haulers, because it reduces the total ∆V stress accumulation on the frame of the ship, and they’re usually not being paid for speed anyway). I prefer my space-flight dynamics to be more Kerbal-featured, though. XD

Starting from a 715 km orbit, with an orbital period of about 1 hour and 40 minutes, the orbital velocity would be about&nbsp;7500 m/s. At 3 Gs, it would take the Artemis about 4.25 minutes to reduce the orbital velocity to 0. During that time, gravity would drop the ship about 80 meters, and give it and the G-Carrier about 40 m/s of downward velocity. In about 2 minutes, the Artemis would negate its downward velocity after falling another 40 meters, with a planetary altitude of about 600 meters, and loiter over the target location; alternately, the Artemis could simply accelerate away for another 4 or so minutes, devoting all thrust to regaining orbit rather than negating gravity. Still trying to work out the acceleration of the G-Carrier...

Speaking specifically about Beck's World now, we're in luck because Beck's is a size 8 world - just like earth! I still think 715kms is way too high. If Grobble is keeping the Athena in orbit for the specific purpose of being able to drop a G-Carrier when called the orbit is going to be lower. A normal low orbit - like most satellites and the International Space Station, is between 300 and 400km. Sputnik orbited at a little over 200kms. I don't think any of these orbits would be so close as to be "suspicious" to ground control. So like you said TT, Athena burns 3Gs for about 4 mins to negate the orbital velocity. I think the math about how far we would drop during that burn is a little off though. Maybe you put in the minutes as seconds? If I have it figured right (this is rough) our acceleration toward the planet gradually increases as the orbital velocity is reduced until it gets up to about 9m/s^2 when orbital velocity =0. So if we average the acceleration toward the planet out over that 4 minute burn ( I know it wouldn't actually be a straight average but we're after a rough number here ) we get the distance dropped looking like: t is 255seconds (4.25 minutes) a is average acceleration toward planet (0+9)/2m/s^2 d=1/2at^2 d = 4.5/2 x 255^2 Distance dropped after 4.25 min burn = about 146km This is an overestimate because the acceleration toward the planet would increase in a gradual exponential way and not just be averaged out like I've done it. But I think that's pretty close. So if we began our burn at an altitude of 400kms, we would end up with an altitude of about 250kms by the end of it. The velocity toward the planet would be: v = at v = 4.5 x 225 Falling toward the planet at the end of the 4.5 minute burn at a velocity of about 1012.5m/s Burning the Athena's drives at 3Gs for 50 seconds would negate that downward velocity ( 30m/s^2 -10m/s^2 (gravity) =20m/s^2. 1012/20 = 50 seconds ) so if we wanted to release the G-Carrier without such a severe speed toward the ground we easily could.

So assuming that Grobble releases the G-Carrier at an altitude of 250kms with Athena's orbital velocity of 0 and a downward velocity of 0 it now comes down to guessing how long it would take for the Carrier to fall down through the atmosphere and hit the ground. The easiest way to guess the travel time would be to calculate it as if the G-Carrier travels that distance at it's max speed (640km/h) for most of the trip. Acceleration due to gravity will help it reach that speed pretty quickly, and the dense atmosphere will help it brake pretty quickly too I'd imagine. So figuring out the time including acceleration is probably a waste of time now that I think about it. Most of the trip would be at the carriers max (terminal) velocity of 640km/h.&nbsp; That means our Express Elevator to Hell would take 23.5 minutes to fly from the Athena to the LZ. That's my best and final guess ... or at least the only guess I have the mental energy to come up with at this time in the AM. If we wanted to be ultra realistic we would shave time off because of the initial part of the trip where there is no atmosphere and where the acceleration due to gravity and the Carrier's own drives would push it's speed above 640km/h. But once it hits denser atmosphere, and then circles around looking for a spot to land ... my guess it we'd be getting back to a number around 20 mins. I really don't think we need to worry about burning up in the atmosphere. For one, the space shuttle and other ships burn up because the use friction flying through the atmosphere to reduce their massive orbital speed. Our max speed will be way lower. As soon as acceleration due to gravity helped our G-Carrier hit it's desired speed the acceleration could be negated by the G-Carriers drives. All G-Vehicles would need to be able to negate at least 1G to be able to fly. Second, I think Bonded Superdense armour would be able to handle reentry. A vehicle designed to travel to orbit really needs to be able to travel from orbit too ( "orbit" as in the altitude - not an actual orbit - see rant above ).

I am thinking that airrafts and G carriers use their anti gravity drive to basically move upward to "orbit" (basically you could consider this the minimum height to reach a semi stable orbit without atmosphere causing a decay over a meaningful length of time? maybe?) But once it reached that height, it would have to speed up to match the orbiting velocities of anything in orbit, at the same time if a ship in orbit had antigravity drives, it could simply "hover" without falling, but not orbiting. But then we get into the issue that the planets themselves are moving as well, so the anti gravity drive would have to let enough gravity effect it to pull the ship along with the planet, but not let the ship actually fall against it. Otherwise you'd just end up in a fixed spot in space. To reenter it would be a simple matter of keeping your AG drive active so you don't fall and negate any forward velocity from orbiting by thrusting in the oposite direction until your orbital velocity was roughly 0 or a number inconcequential to actually reentering, and then use the AG drive to slowly float down through atmosphere. All that said, an AG drive would really just operate kind of like a downward facing engine that has enough thrust to infinitely push upward until it runs out of power. That said, any ship in orbit could effectivly use its own drives in a simliar fashion (where they negate their forward velocity and simply use their main engines to keep them from falling into the gravity well of the planet, but keep them at a level where they arn't escaping from the gravity well either.. basicaly letting them "hover" such a hovering ship would be able to recover an airraft from the planet without forcing it to match an orbiting velocity.

Yeah pretty much. Still baffled by air/raft design. Make a vehicle capable of going into orbit open topped? Nobody on the design team thought of putting a roof on that thing? It does look cool and sporty and everything ... but having to wear a vaccsuit is less sporty.

Alby said: Yeah pretty much. Still baffled by air/raft design. Make a vehicle capable of going into orbit open topped? Nobody on the design team thought of putting a roof on that thing? It does look cool and sporty and everything ... but having to wear a vaccsuit is less sporty. <a href="http://orig09.deviantart.net/f7cb/f/2013/253/5/c/t" rel="nofollow">http://orig09.deviantart.net/f7cb/f/2013/253/5/c/t</a>... there are some nice enclosed designs.&nbsp;

Oh yeah. In the core rules there is no such thing though. You have to start digging round to find that stuff. It's as if the player base was forced to publish their own stuff. Looking at the fine print on that image - what's a "fairing field"?

Alby said: Oh yeah. In the core rules there is no such thing though. You have to start digging round to find that stuff. It's as if the player base was forced to publish their own stuff. Looking at the fine print on that image - what's a "fairing field"? My best guess is like a deployable cover, akin to a technologically advanced "convertible" dunno if its energy "hard light" or physical. Rocketry wise, a fairing is basically a cover for sensitive instruments/payloads that make the rocket aerodynamic.&nbsp; It also might just mean the windshield in the front.

Wiktionary Fairing. n. A structure on various parts of a vehicle, for example an aircraft, automobile, or motorcycle, that produces a smooth exterior and reduces drag So I guess it's a "field" that does that? Traveller hasn't usually been a setting where "force fields" are a thing, but there were gravitational "repulsors" back in the classic High Guard book that deflected missiles. Maybe a small scale version of something like that being used to "repulse" the atmosphere around the vehicle? Hair would get pretty messy in an open topped vehicle at 400km/h, so I can see why there'd be a market for something like that.

As for my math (basic orbital calculation done here:&nbsp; <a href="http://keisan.casio.com/exec/system/1224665242" rel="nofollow">http://keisan.casio.com/exec/system/1224665242</a> ), I may have gotten parts wrong, here’s a redo, but that doesn’t mean it works in our favor... Orbital Altitude: 715 km Orbital Period:&nbsp;01:39:05.23 Orbital Velocity:&nbsp;7496.3465199837 m/s Orbital Velocity/3Gs =&nbsp;7496.3465199837 {m/s}/(9.8 {m/(s^2)}*3) =&nbsp;254.97777278856122 {s} =&nbsp;4.24962954647602 {min.} Peak Drop Velocity (using an assumed acceleration of 9 {m/(s^2)}) =&nbsp;254.97777278856122 {s} *&nbsp;9 {m/(s^2)}) =&nbsp;2294.79995509705098 {m/s} Average Drop Velocity =&nbsp;2294.79995509705098 {m/s}/2 =&nbsp;1147.39997754852549 {m/s} Drop Distance during Retrograde Acceleration =&nbsp;1147.39997754852549 {m/s} * 254.97777278856122 {s} =&nbsp;292.56149077296818 {km} Time during Acceleration to Stopped Hover = 2294.79995509705098 {m/s} /&nbsp;(((9.8 {m/(s^2)}) * 3) - 9&nbsp;{m/(s^2)}) =&nbsp;112.49019387730642 {s} Drop Distance during Stopped Hover =&nbsp;1147.39997754852549 {m/s} * 112.49019387730642 {s} =&nbsp;129.07124592925067 {km} Total Drop Distance =&nbsp;292.56149077296818 {km} +&nbsp;129.07124592925067 {km} =&nbsp;421.63273670221885 {km} Altitude at Resumption of Orbit =&nbsp;293.3672632977812 {km} Orbital Velocity Required From Stopped Hover: 7729.5985376648 {m/s} Time to Acceleration to Orbit From Stopped Hover = 7729.5985376648 {m/s}&nbsp;/&nbsp;(((9.8 {m/(s^2)}) * 3) - 9 {m/(s^2)}) =&nbsp;378.90188910121569 {s} =&nbsp;6.31503148502026 {m} Alby, keep something in mind about that 715 km - 293 km orbit trajectory... that’s the perfectly executed results. Considering Imperfect &nbsp;Execution, there’s only a narrow window for the Artemis to avoid hitting the atmosphere all wrong . This is about as narrow a window as you want for a military style margin of error. I think we should keep it that way. And it’s not the resulting orbit that would be suspicious, per se... it’s the method of transition; there’s no reason for a typical starship to maneuver this way. Once we execute a transition like this, dropping off a G-Carrier, it’s a signal to anyone watching that something interesting is going on, because of how completely out of the ordinary it is for a Starship to completely negate its orbital velocity, and then drop like a rock; under routine conditions, the ship wouldn’t bother, and the G-Carrier would do it on its own, taking its own sweet time if necessary. The G-Carrier absolutely shouldn’t brake on account of atmosphere for any reason; it’s not built for atmospheric reentry. Once its max velocity limit is reached, it should hold that all the way down to the surface. How long it takes to reach that velocity is, unfortunately, an open question; I see the G-Carrier accelerating faster than the starship with no atmosphere to hold it back as a legitimate possibility, negating the need for this whole maneuver. To my mind, atmospheric reentry is what distinguishes Shuttles from G-Carriers in this specific scenario; G-Carriers landing from orbit is a bit of a “hack”, and should be limited by common sense. In my personal opinion, even Vehicle Grade Bonded Superdense should be assumed as not being capable of sustaining 1650˚ C so broadly over a craft, and for so long (and, honestly, so long as the same armor type is being used for spacecraft that never need to land, I wouldn’t assume it for Starship Grade Bonded Superdense, either). You’re also neglecting the issue of “Where in our 1-hour-40-minute orbit does our ship receive the landing request?”. If it takes 54 minutes for the ship to reach the point at which it should execute G-Carrier dropping maneuver, that means that the G-Carrier landing is about another whole hour away from the stop-and-descend time.

None of your math tells us how long it takes for the Carrier to get to the ground - which is the number we're after. To answer some of your ponits: Alby, keep something in mind about that 715 km - 293 km orbit trajectory... that’s the perfectly executed results. Considering Imperfect Execution, there’s only a narrow window for the Artemis to avoid hitting the atmosphere all wrong. This is about as narrow a window as you want for a military style margin of error. I think we should keep it that way. Nar. We have 3Gs of acceleration. We're never really at the mercy of the planet's gravity or atmosphere. 3Gs gives us the ability to put our ship exactly where we want it. For us it's just a matter of figuring out how long it will take. We have the ability to use brute force. If we wanted to we could put 2Gs into negating orbital velocity and keep 1G burning toward the world to negate acceleration due to gravity. Once we have an orbital velicity of zero we could maneouver exactly to whatever altitude we wanted to. So our initial height isn't really too important. I was just using orbital mechanics to figure it out in a wakny, nerdy kind of way. None of it is really nessisary. Just an example of what I'm talking about - we could be in actual geo-stationary orbit 35,786kms above the LZ. (lets pretend this planet has a regular 24 hour rotation like earth for a moment). If we burn for 2.75 Gs (2.5m/s^2 is used to negate 3km/s orbilat velocity) to mid point and then burn by the same amount till we're stationary 100km above the LZ (still above the "Sky" so to speak. Atmosphere extends out to about 17kms tops.) At which point we drop the carrier which zoomz down to land, taking her about 6mins. The example above would take about 38 mins. T ime = 2 x Square Root of (distance/acceleration) Time =2x√(35,786,000/27.5) Time = 38m mins. The G-Carrier absolutely shouldn’t brake on account of atmosphere for any reason; it’s not built for atmospheric reentry. Once its max velocity limit is reached, it should hold that all the way down to the surface. How long it takes to reach that velocity is, unfortunately, an open question; I see the G-Carrier accelerating faster than the starship with no atmosphere to hold it back as a legitimate possibility, negating the need for this whole maneuver. To my mind, atmospheric reentry is what distinguishes Shuttles from G-Carriers in this specific scenario; G-Carriers landing from orbit is a bit of a “hack”, and should be limited by common sense. In my personal opinion, even Vehicle Grade Bonded Superdense should be assumed as not being capable of sustaining 1650˚ C so broadly over a craft, and for so long (and, honestly, so long as the same armor type is being used for spacecraft that never need to land, I wouldn’t assume it for Starship Grade Bonded Superdense, either). Well ... G-Carrier doesn't need to use atmosphere to brake if the Athena has already reached a stationary position over the LZ, so I'm not really sure why it's being brought up again. We know the G-Carrier's maximum velocity in an atmosphere so figuring out how long it would take to accelerate up to that speed (9m/s^2 if she is just falling) isn't really hard at all. Not sure what makes you think it could accelerate toward the ground faster than the ship when the ship can zoom in at up to 30M/S^2 ... not that it would be because it's stationary above the LZ... Will finish later. But... yeah no matter how I look at it the time to ground always seems to be around 20-30 mins. EDIT:&nbsp;1650˚ C isn't actually all that hot. A candle flame burns at 829 °C. A propane blowtorch at 1,995 °C. Superdense armour is material that "that has had its molecular structure partially collapsed in a massive artificial gravity field, which increases its density and strength." Bonded Superdense is then strengthened "with a small induced electronic current to strengthen the internal electron bonds which further increases the hull strength." I'm pretty sure that material designed to deflect damage from lasers and high energy weapons will easily resist the heat of reentry. .. not that reentry from a stationary position above the atmosphere would actually create friction that would heat up the hull at all. Remember, the spaceshuttle burns up because she's travelling through the atmosphere at 28,000km/h. We're not getting anywhere near those speeds. The actual difference between our shuttle and a G-Carrier is that the shuttle can travel in space. Our G-Carrier is never going to be able to make a trip from a system's main world to the closest gas giant. That's a job for the Shuttle. I'm also thinking that Grav Vehicles are designed to travel from an "orbit" altitude to the ground. Thinking about it from a "common sense" standpoint - if you design a vehicle to reach that altitude, you would need to design it to descend from that altitude. Being able to go up but not come down seems a bit absurd. Otherwise there'd need to be a warning sticker on the dash - "warning - flying above N kms is a one way trip. Do not attempt to land once you are flying above N kms."

Alby, the drop in Orbital Altitude was done with 3Gs of acceleration; it can’t happen any faster without 4Gs; feel free to check the math. Spending a G combating the drop in Orbital Altitude would mean that the ship would take longer to stop over the target location, increasing the time taken for the G-Carrier to arrive at the target destination; which we don’t want. The number that matters for gameplay purposes , and thus, is the number we have to care about, is the time it takes for a request to be made from the ground to orbit to result in a landing of the G-Carrier on-target. All the steps in-between have to be included, which means considering how long it would take if the ship were on the other side of the planet at the time. I mentioned Aerobraking because you mentioned Aerobraking; we should assume the G-Carrier can’t Aerobrake at any velocity faster than its maximum velocity. I assume the G-Carrier can accelerate faster than a Starship because how fast a G-Carrier can fly in atmosphere is a primary performance constraint that is negated directly by the G-Carrier’s acceleration. How fast a Starship can accelerate outside atmosphere is a secondary performance constraint, because total trip time for Starships depends primarily on the performance of the Jump-Drive; how fast a Starship can accelerate inside atmosphere, which is entirely optional for Starships, and which is the key basis for comparison here, is, at best, a tertiary performance constraint. It stands to reason that a Starship, being a larger collection of design compromises, might have less acceleration performance than a G-Carrier, a much more purpose-specific vehicle, just as the Shuttle does. We can’t start arguing the properties of materials with fictional properties of matter; if the books don’t tell us the performance of those materials explicitly, we should assume nothing else about them. Let’s take your example of lasers, for a moment; suppose Bonded Superdense depends on adjacent patches wicking away the thermal energy of the laser pulse to prevent damage; which is a reasonable assumption, because it’s not as if laser beams are so wide that the entire ship’s surface gets blasted at once; if we then put a ship in exactly that situation , by submitting massive patches of the ship to massive thermal loads on atmospheric reentry, there’s nowhere for the heat to go,&nbsp;the armor gets destroyed during reentry, and the ship burns up . The book doesn’t say anything about which assumptions, and thus, which conclusions, are correct, so we shouldn’t assume either one &nbsp;(I think mine are more realistic, though). The problem with the G-Carrier dropping down from orbit is that there are no physical properties keeping the G-Carrier from exceeding its by-design maximum velocity; with no air in the way to stop it, it can just keep accelerating, until it hits whatever its “burn up on reentry” speed is; the&nbsp;G-Carrier Pilot behaving reasonably, and the G-Carrier’s safety and performance features remaining intact, are the only things keeping this from happening. An important thing to consider is that we are poorly constraining the problem; the G-Carrier could exceed its by-design maximum velocity outside of the atmosphere by accelerating toward the planet and then decelerating before it hits the atmosphere; or, it could accelerate so anemically that it barely opposes gravity enough to slow down enough before hitting the atmosphere to begin with; without a solid acceleration number for the G-Carrier, we won’t know what we’re dealing with. I’m not saying that G-Carriers can’t go both up and down; I’m just saying that they have to do it anemically, because they weren’t designed for atmospheric reentry; it’s sort of like saying a mail truck can drive around a racetrack; yes , but ... Geostationary Orbit makes our point of interest obvious; better to keep a reasonably tight orbit that is not so tight that we can’t execute this maneuver safely; I think our 700 km or so orbit fits.

Tenacious Techhunter said: Alby, the drop in Orbital Altitude was done with 3Gs of acceleration; it can’t happen any faster without 4Gs; feel free to check the math. Spending a G combating the drop in Orbital Altitude would mean that the ship would take longer to stop over the target location, increasing the time taken for the G-Carrier to arrive at the target destination; which we don’t want. Well burning 2Gs instead of three means we slow down in 6 mins instead of 4mins. Difference of about 2 mins. The 2G burn was really just an example of how we don't have to act like gravity is our big enemy. My initial idea was pretty much identical to yours - that we burn all 3Gs into negating orbital velocity, and once we are above the LZ burn all 3Gs into negating velocity toward the planet. All this is haggling over a few minutes. The differences aren't really all that great. The number that matters for gameplay purposes , and thus, is the number we have to care about, is the time it takes for a request to be made from the ground to orbit to result in a landing of the G-Carrier on-target. All the steps in-between have to be included, which means considering how long it would take if the ship were on the other side of the planet at the time. Yeah you're right about this. Where we are when we take the call is the big one. I guess if the time to make an orbit is about 90 mins then we're looking at a random number between 0 and 90 mins would need to be added to the time it takes to drop from orbit to the ground? If we were using poly dice (1d10-1)x10 mins? Time to brake and insert the ship into a stationary position above landing zone: 6 mins - 10sec per effect of pilot skill roll effect. (probably an "Easy" or "Routine" check?) To make it super easy: Time to drop to the ground from stationary point above LZ: (Altitude/max speed of G-vehicle)*60 (minutes) - effect if Flyer (grav) skill check x 10 seconds or Navigation skill check x 10 seconds (maybe?) ^ This totally avoids the whole "burn up" issue. G-Carrier pilot uses grav to brake and never lets the carrier travel above 640km/h

I did my calculations in terms of bare minimums, so we have a baseline to apply plausible error from; don’t forget, those 2 minutes are 12 rounds . If your orbital period is, as per our example, 1 hour and 40 minutes, and it would take you an 8.5 minute burn to reverse direction, then the time it would take to reach the target is, at most, half of the sum of those two numbers, for 54.25 minutes; there’s a point in the orbit 45.75 past the target where it makes just as much sense to turn around as it does to keep going, when time to the target is the main concern. This, of course, is the bare minimum, and execution matters, especially since you’d be scraping the atmosphere. Yes, assuming a constant velocity for the G-Carrier allows us to ignore that problem; but it also means that we’re using a rather conservative number for our baseline; I’d rather know what the perfect number is, and apply some reasonable error to that.

... Still think it would have made more sense to call those guys from the starport instead of from orbit. Just say'n.