I've put together the stats for the Terra system as they stood in 1106 as harvested from 'Book 6: Scouts' and the 'Solomani and Aslan' sourcebook. I also added stats for Eris, though not Ceres for a variety of reason. Some things stand out.
1. You'd expect the colony on Mars to be larger, frankly. Yes, there are terraforming efforts underway according to some Traveller write ups, but that would make it gradually easier to colonize and more desirable to populate.
2. Ganymede has a military base and a class F spaceport. Really, that should be at Callisto, since the radiation at Ganymede (and Io and Europa) is just too high as probes sent since the 1970s have proven out. Flipping their stats would seem prudent, though clearly any research lab at Ganymede would need special shielding and would probably be concerned with the interaction of the magnetic fields of Ganymede and Jupiter along with perhaps radiation mediation (e.g. better nuclear dampers).
3. Even in 57th century, helium-3 would be a desirable commodity, so one would expect that Saturn would have substantial colonies on more than one of its moons, which unlike many of Jupiter's moons would be free of intense radiation. Indeed, it would be possible to have floating colonies in Saturn's upper atmosphere dedicated to gathering helium-3 or simply places where the quirky, outcasts, and loners can live truly "getting away from it all".
4. Similarly, helium-3 mining operations would be taking place at Uranus and Neptune, though because of the distances, the colonies there would be small and the mining operations largely robotic in nature.
5. I was never totally satisfied with DGP's description of Earth, particularly the rise in sea levels, not that global warming isn't a thing, but the introduction of fusion power plants (likely within our lifetimes no less according to the Traveller timeline) would pretty much halt sea level rise and in the intervening 3,600 years new technologies and environmental management techniques would mean that the polar caps would either have been restored or never have melted completely away to begin with.
My plan to do a new write up of the Terra system with some revisions to the background and advancing the storyline up to 1202 or so. Let me know if you have additional input or additional sources I should be checking.
RE: point 2 - radiation won't be a problem if the base is underground or shielded. Here's something I wrote up for a discussion about Transhuman Space many many years ago on the subject:
I've tracked down some radiation levels at the surfaces of each of the Galilean satellites, so we can get an idea of habitability of their surfaces. This is further to my impression that Ganymede's magnetic field could serve to shield the surface somewhat from radiation...
Numbers are from "Energetic Ion and Electron Irradiation of the Icy Galilean Satellites" by John F. Cooper et al in the January 2001 "Icarus" (Vol. 149, pg. 133-59), which is is full of very detailed analysis of the radiation doses of different parts of the surfaces of the three icy Galileans. Usefully, it provides a graph showing the radiation in MegaRads per month (28 days presumably).
Important things to note: even under a centimetre of water ice, the radiation levels drop dramatically compared to what they're at exactly on the surface. Behind sturdier shielding (eg metals) this protection could be even more significant.
Below a surface layer of one hundred-thousandth of a gram per square cm of water ice (that is, virtually on the surface), Europa gets about 1500 megarads per month; Ganymede's polar caps 350 megarads; Ganymede's equator 150 megarads; and Callisto 30 megarads. But beneath only a 1-cm layer of solid water ice, the doses plummet to only 300,000 rads for Europa, 6000 rads for Ganymede's polar caps, and a mere 100 rads per month for Callisto and for Ganymede's equator.
Figures are unclear for Io, but it seems a value of between 15 and 60 times that of Europa is appropriate. So let's assume 30 times Europa - 45000 megarads/month for the surface, 9 megarads/month under 1 cm of ice. (well, OK, it's not ice, but just to be consistent in this table we'll assume it is). (NB. 1 megarad = 10E8 ergs/cubic centimetre).
Translated into rads/sec:
Satellite Surface under 1 cm of ice
----------------------------------------------------------
Io 18600 rad/sec 3.72 rad/sec
Europa 620 rad/sec 0.124 rad/sec
Ganymede Poles 145 rad/sec 0.0025 rad/sec
Ganymede Equator 62 rad/sec 0.00004 rad/sec
Callisto 12.5 rad/sec 0.00004 rad/sec
So it seems the safest places to be are in the equatorial regions of Ganymede and on Callisto (under some shielding, that is!). Under 1 cm of ice shielding, at the levels quoted above, a person will suffer a dose of 0.144 rads/hour or 3.456 rads/day. However, thicker shielding will provide more protection UP TO A POINT.
Thanks to the Bremsstrahlung radiation (X-rays and gamma rays) produced within the material of a shield itself as it stops high-energy charged particles, there's a point beyond which even very thick shielding sharply loses its ability to reduce radiation dosage at Jupiter. Indications are that beyond a shield thickness of about 25 cm of aluminium, the radiation dose at Europa tends to stick at around 500 rads per month.
For heavier materials (e.g. lead) this thickness can be greater before the Bremsstrahlung radiation becomes important.
Callisto is in a zone where it benefits from Jupiter's protection in terms of cosmic rays, but doesn't get a radiation bath requiring massive amounts of shielding. It's also closer to the edge of Jupiter's the gravity well than the inner satellites. Ganymede does indeed have its own magnetosphere, but there are questions as to whether it provides the amount of protection you indicate (consensus seemed to be much less). While it is true that you can burrow down in the ice/rock and find protection from much of the radiation exposure (even on Europa), it's still much easier to colonize Callisto than Ganymede (lots of water ice, geologically stable, etc.), which is why NASA picked it as a potential target for a manned expedition.
Hi Harold, I like what you did with the system. I've gotten into the rut of looking at the UPP and picturing the main world and never giving a thought about other destinations in the system! A J-Hawk crew could make a good living just going to out system destinations, places where the heavy haulers would turn up their noses at going.
I see your point about Ganymede being to hot for a normal military base and Callisto being more appropriate, but I could see Ganymede being desirable as a military research base. Just the thought of being microwaved on approach would serve to keep most people away. I can see black ships with heavy dampers flying into underground hangers.
When I saw Eris way out and the end of the system I pictured a shipwreck station. Maybe a 29 ton quarters module next to a space where someone had cleared the rocks of a bit of ground and maybe a few wreaks dotting the area.
Roger
On Eris you are probably looking at a landing spot, marker beacons, and an automated observation station that is used for scientific as well as military applications. From time to time, starships would jump out to the site and a crew would do maintenance tasks that the robots weren't up to the task of completing. This would also be the home of the Terran Archives, a vault housing a variety of data (yottabytes and yottabytes of it...yes a yottabyte is a real thing) in a variety of formats and would include everything from the writings of Ovid to high resolution photos of Ming dynasty art to recordings of 19th century Sioux Ghost dancers to Chuck Berry performances to architectural plans for the United Worlds Headquarters to...well anything else that would constitute evidence that humans once lived in this star system. The Terran Archives would constitute the ultimate time capsule, with the idea being that if Mankind meets its end, alien travelers
billions of years from now could find it and know that we were here.
Adventure stubs...
1. The player characters are hired to be part of a crew that goes out to service the automated observation station. One of the crew turns up dead and one of the PCs is implicated in the murder.
2. The player characters are hired by a historian to take the him/her to Eris to check on the Terran Archives and do routine maintenance. The PCs discover that not everything the Solomani Party has been saying about the history of Terra is accurate and must decide if want to reveal the what they found to others. Additional twist: one of the party is a member of Solsec and will do anything to ensure that anything that contradicts the Solomani Party line is suppressed.
3. (campaign set in early Terran history) The PCs are explorers sent to investigate Eris in an early J-1 Terran scientific research vessel. While there, they lose their communications systems and their jump drive becomes disabled. Bad luck, sabotage by a rival nation's intelligence service, or is there something else not of this Solar system going on...?
4. (TNE/Striker II) The PCs are Terran Marines being sent to "de-bug" Eris, take control of the Virus-infected observation station, and secure the Terran Archives. Meeting more resistance than they anticipated, do they take off and "nuke the entire site from orbit, it's the only way to be sure" and destroy the Terran Archives in the process, or do they try to use a more subtle approach?
The values from the newmars forum have no references, so I have no idea where they got them from (and they look extremely small and wrong - those are in "rems/day", mine are *rads per second*. The values I used are from a 2001 paper on the subject which I do reference, so I'd advise you to use those unless you can find a referenced source that's more accurate.Ganymede39;s magnetosphere doesn't provide much protection at all. If you look at the numbers I quoted, the radiation is focussed at Ganymede's poles (which is where the field lines of the magnetic field are coming in and so any particles trapped in them are bombarding the surface - that's why we get aurorae, because our atmosphere is in the way) and lower at the equator, but they're still deadly either way. The radiation anywhere on ganymede would still kill unprotected human (ignoring vacuum/temperature effects) in less than a minute - heck, even on Callisto a human would get a fatal dose in about two minutes.
As for digging underground, you only have to be exposed at the surface long enough to dig a hole to get under cover (or to shovel enough ice over yourself as extra protection) - once you've got that far then you can safely dig away with a metre or two of ice above your head - nuclear damper technology would also probably help too.
I'd like to find a source(s) of data that was written in the last 4-5 years if possible. My sense is we know a whole lot more about the subject of Jovian moon radiation exposure at this stage.
Nuclear dampers would indeed be helpful in Traveller terms to reduce radiation exposure, as would tunneling. However those are not the only factors to consider when establishing a permanent colony. It's also going to be amazingly cold, Europa's surface temperature at the equator for example never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius), so all equipment and structures would have to be built to take it. There's also geological stability to consider and while Io may be a cool to watch at a safe distance, you could never put a permanent colony there.
Looks like that was from 2000, referencing Entering Space by Robert Zubrin, from 1999, which may have used older data. The paper I referenced was from 2001 and used Galileo data and went into a lot of detail. I may have had to do some converting of units, but I don't think I did that incorrectly (I did it a long time ago though). You'd have to look up the original paper ( http://people.virginia.edu/~rej/papers03/Cooper01.pdf ) and look it over.
Regarding bremsstrahlung, there is an article on astrobiology.net which suggests that around one metre of ice is sufficient to shield from bremsstrahlung on Europa and Ganymede.
"The ions from the belt can penetrate about a millimeter into the ice. Electrons reach roughly a centimeter down, but they also emit high-energy photons that can go as far as a meter deep. Regardless of the type of radiation, these high-energy particles will rip electrons off of molecules, thereby "oxidizing" everything on the surface"
"Indications are that beyond a shield thickness of about 25 cm of aluminium, the radiation dose at Europa tends to stick at around 500 rads per month. For heavier materials (e.g. lead) this thickness can be greater before the Bremsstrahlung radiation becomes important."
I thought Bremsstrahlung increased with the square of Atomic Number. Surely lead should be a worse shield than aluminium?
Eamon
Sent from my iPad
On 20 Aug 2014, at 08:55, " [Traveller_TNE]" <> wrote:
> RE: point 2 - radiation won't be a problem if the base is underground or shielded. Here's something I wrote up for a discussion about Transhuman Space many many years ago on the subject:
> I've tracked down some radiation levels at the surfaces of each of the Galilean satellites, so we can get an idea of habitability of their surfaces. This is further to my impression that Ganymede's magnetic field could serve to shield the surface somewhat from radiation...
>
> Numbers are from "Energetic Ion and Electron Irradiation of the Icy Galilean Satellites" by John F. Cooper et al in the January 2001 "Icarus" (Vol. 149, pg. 133-59), which is is full of very detailed analysis of the radiation doses of different parts of the surfaces of the three icy Galileans. Usefully, it provides a graph showing the radiation in MegaRads per month (28 days presumably).
>
> Important things to note: even under a centimetre of water ice, the radiation levels drop dramatically compared to what they're at exactly on the surface. Behind sturdier shielding (eg metals) this protection could be even more significant.
>
> Below a surface layer of one hundred-thousandth of a gram per square cm of water ice (that is, virtually on the surface), Europa gets about 1500 megarads per month; Ganymede's polar caps 350 megarads; Ganymede's equator 150 megarads; and Callisto 30 megarads. But beneath only a 1-cm layer of solid water ice, the doses plummet to only 300,000 rads for Europa, 6000 rads for Ganymede's polar caps, and a mere 100 rads per month for Callisto and for Ganymede's equator.
>
> Figures are unclear for Io, but it seems a value of between 15 and 60 times that of Europa is appropriate. So let's assume 30 times Europa - 45000 megarads/month for the surface, 9 megarads/month under 1 cm of ice. (well, OK, it's not ice, but just to be consistent in this table we'll assume it is). (NB. 1 megarad = 10E8 ergs/cubic centimetre).
>
> Translated into rads/sec:
>
> Satellite Surface under 1 cm of ice
> ----------------------------------------------------------
> Io 18600 rad/sec 3.72 rad/sec
> Europa 620 rad/sec 0.124 rad/sec
> Ganymede Poles 145 rad/sec 0.0025 rad/sec
> Ganymede Equator 62 rad/sec 0.00004 rad/sec
> Callisto 12.5 rad/sec 0.00004 rad/sec
>
>
> So it seems the safest places to be are in the equatorial regions of Ganymede and on Callisto (under some shielding, that is!). Under 1 cm of ice shielding, at the levels quoted above, a person will suffer a dose of 0.144 rads/hour or 3.456 rads/day. However, thicker shielding will provide more protection UP TO A POINT.
>
> Thanks to the Bremsstrahlung radiation (X-rays and gamma rays) produced within the material of a shield itself as it stops high-energy charged particles, there's a point beyond which even very thick shielding sharply loses its ability to reduce radiation dosage at Jupiter. Indications are that beyond a shield thickness of about 25 cm of aluminium, the radiation dose at Europa tends to stick at around 500 rads per month.
> For heavier materials (e.g. lead) this thickness can be greater before the Bremsstrahlung radiation becomes important.
>
And even more of an issue when the units are for different things. Rem is for the biological dose, i.e. the effect of the radiation, rads are for the basic radiation dose to any medium. They are outmoded, being replaced in most countries by the SI Units sievert and gray.
I don't think nuclear dampers would be much use, as they only effect radioactive decay of materials: the radiation belts of Jupiter are largely made of of radiation particles, electrons and ions, IIRC.
Eamon
Sent from my iPad
On 21 Aug 2014, at 12:54, "Harold Hale [Traveller_TNE]" <> wrote:
> Mixed units can definitely be an issue. I found these lecture notes that the source of some of the data:
>
> http://zimmer.csufresno.edu/~fringwal/w08a.jup.txt
>
> I'd like to find a source(s) of data that was written in the last 4-5 years if possible. My sense is we know a whole lot more about the subject of Jovian moon radiation exposure at this stage.
>
> Nuclear dampers would indeed be helpful in Traveller terms to reduce radiation exposure, as would tunneling. However those are not the only factors to consider when establishing a permanent colony. It's also going to be amazingly cold, Europa's surface temperature at the equator for example never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius), so all equipment and structures would have to be built to take it. There's also geological stability to consider and while Io may be a cool to watch at a safe distance, you could never put a permanent colony there.
>
Nuclear dampers affect strong and weak nuclear forces. I think that means that they could be used as "radiation shields" in the sense that they could cause any incoming particles to just scatter off anything they hit rather than causing damage (e.g. chemical bonds wouldn't be broken, particles won't be sputtered off a surface by bombardment etc). Or they could affect the incoming particles directly by causing them to decay prematurely or decrease in energy before they reach the surface?
FF&S, page 57 gives a good description of how nuclear dampers work. In summary, they create interference fields in the strong and weak nuclear forces. In the strong positive and negative nodes that result the nuclear forces are respectively reinforced, or reduced. It is also directional, requiring a beam pointer. In summary, they affect the rate of atomic decay.
If they caused particles to deflect then there's a momentum transfer going on - which would appear to violate the laws of physics. That effect could be realised by using strong magnetic fields, so that's an option for the inner Jovian satellites.
Causing the particles to decay would not affect beta radiation, as electrons can't decay. It would likely not affect protons either, as they are not observed to decay (some theories allow for this, but no supporting evidence has been found.
I suppose that theoretically stable ions could be made to decay using dampers, but energy, incoming speed, and an inability to track them - and thus focus nodes on them - would seem to mitigate against this.
I'd say dampers are out, but magnetic fields could be in.
Eamon
P.S. Sorry for the delay in reponding. Things got busy.
--------------------------------------------
On Fri, 22/8/14, [Traveller_TNE] <> wrote:
Subject: Re: [Traveller_TNE] Re: The Terra System
To:
Date: Friday, 22 August, 2014, 15:48
Nuclear dampers affect strong and weak nuclear
forces. I think that means that they could be used as
"radiation shields" in the sense that they could
cause any incoming particles to just scatter off anything
they hit rather than causing damage (e.g. chemical bonds
wouldn't be broken, particles won't be sputtered off
a surface by bombardment etc). Or they could affect the
incoming particles directly by causing them to decay
prematurely or decrease in energy before they reach the
surface?
#yiv2153974544 div#yiv2153974544ygrp-mlmsg
#yiv2153974544ygrp-msg p a span.yiv2153974544yshortcuts {
font-family:Verdana;font-size:10px;font-weight:normal;}
So essentially, we're back to burying any bases, settlements, etc. at least a meter down, preferable more to be safe, though at some point at high tech levels, it would be possible for some portion of the installations above ground if they were adequately protected. Also how exactly would a magnetic field generator work in relation to a terrestrial base on a Jovian moon though? Artificially generated magnetic fields could be problematic given the amount of power required.
That becomes important especially since I'm writing some background for each of the planets/moons/etc. to supplement the data.
Also, as a side note, the literature I've read so far seems to indicate that the radiation problems that would be experienced around the Jovian moons would not be present in relation to the moons of Saturn, Uranus, or Neptune for a variety of reasons (distance from the planet, weaker radiation field).
I'm unsure as to how the magnetic field generators would work, but on the subject of energy, TNE starships can easily generate GW outputs in a reasonably small package. It may even be possible to use the radiation, which has an electric charge, to generate electricity for the base.
Of course, you have to wonder what the purpose of the base is.
Another question would be, can ships operate in the area with: no problems, with precautions, or need special modifications?
Eamon
Sent from my iPad
On 27 Aug 2014, at 11:11, "Harold Hale [Traveller_TNE]" <> wrote:
> So essentially, we're back to burying any bases, settlements, etc. at least a meter down, preferable more to be safe, though at some point at high tech levels, it would be possible for some portion of the installations above ground if they were adequately protected. Also how exactly would a magnetic field generator work in relation to a terrestrial base on a Jovian moon though? Artificially generated magnetic fields could be problematic given the amount of power required.
>
> That becomes important especially since I'm writing some background for each of the planets/moons/etc. to supplement the data.
>
> Also, as a side note, the literature I've read so far seems to indicate that the radiation problems that would be experienced around the Jovian moons would not be present in relation to the moons of Saturn, Uranus, or Neptune for a variety of reasons (distance from the planet, weaker radiation field).
>
Ultimately is the inverse of whatever technology would go into Bussard
ramjets repelling away the particles.
TL 8 and 9 playing the odds in spacecraft with hardened shelters for
flares or events while most of the ship doesn't want to risk breaking up
alpha particles into more dangerous. Fixed bases needing to be buried, &
specially shielded supply ships etc.
TL 10 mostly EMF though employing gravitics from TL 12 or 13 through
mastery by TL 15. I expect an Imperial facility c. 1116 could have a
"clear" flight path through artificially generated and/or maintained Van
Allen belts. Imagine turning on a Bussard scoop that either collects the
alpha particles or just directs it into a black globe...
Enjoy the discussion. Traveller usually neglects radiation way too much to
fit in a really hard Sci Fi on that factor. Nowhere to fit explicitly in
UWP like atmosphere or gravity, but just as crucial towards
survivability, if not natural biosphere.
- Sent from my SM-N900T
On Aug 30, 2014 9:08 PM, "Eamon Watters
[Traveller_TNE]" <> wrote:
>
>
> I'm unsure as to how the magnetic field generators would work, but on the
> subject of energy, TNE starships can easily generate GW outputs in a
> reasonably small package. It may even be possible to use the radiation,
> which has an electric charge, to generate electricity for the base.
>
> Of course, you have to wonder what the purpose of the base is.
>
> Another question would be, can ships operate in the area with: no
> problems, with precautions, or need special modifications?
>
> Eamon
>
> Sent from my iPad
>
> On 27 Aug 2014, at 11:11, "Harold Hale
> [Traveller_TNE]" <> wrote:
>
>
>
> So essentially, we're back to burying any bases, settlements, etc. at
> least a meter down, preferable more to be safe, though at some point at
> high tech levels, it would be possible for some portion of the
> installations above ground if they were adequately protected. Also how
> exactly would a magnetic field generator work in relation to a terrestrial
> base on a Jovian moon though? Artificially generated magnetic fields could
> be problematic given the amount of power required.
>
> That becomes important especially since I'm writing some background for
> each of the planets/moons/etc. to supplement the data.
>
> Also, as a side note, the literature I've read so far seems to indicate
> that the radiation problems that would be experienced around the Jovian
> moons would not be present in relation to the moons of Saturn, Uranus, or
> Neptune for a variety of reasons (distance from the planet, weaker
> radiation field).
>
>
>
Harold wrote:
>Also, as a side note, the literature I've read so far seems to indicate
>that the radiation problems that would be experienced around the Jovian
>moons would not be present in relation to the moons of Saturn, Uranus,
>or Neptune for a variety of reasons (distance from the planet, weaker
radiation field).
I'll be interested in Dr Ganymede's response to this. Since the canonical
Tavonni system has 4 gas giants, I originally thought it would be cool to
make Tavonni a moon of a Large GG ("Ryzel") - at least until someone (Alvin
Plummer?) pointed out the radiation problem if I wanted a "shirt-sleeves"
world. He suggested changing it to a Small GG instead.
----------------------------------------------------------
David "Hyphen" Jaques-Watson ..at.. Beowulf Down (Tavonni/Vilis/SM 1520)
http://www.tip.net.au/~davidjw
"I file things in historical order, with a hashing algorithm of gravity"
I was just watching Artifaxian by Edgar and he talked about the possibility of placing a garden world at the L4/L5 points of a gas giant in the habitable zone. It's pretty neat series.
https://m.youtube.com/user/Artifexian
Derek Stanley
Sent from my iPad
> On Sep 1, 2014, at 2:44 PM, "'David Jaques-Watson' [Traveller_TNE]" <> wrote:
>
> Dear Folks -
>
> Harold wrote:
> >Also, as a side note, the literature I've read so far seems to indicate
> >that the radiation problems that would be experienced around the Jovian
> >moons would not be present in relation to the moons of Saturn, Uranus,
> >or Neptune for a variety of reasons (distance from the planet, weaker
> radiation field).
>
> I'll be interested in Dr Ganymede's response to this. Since the canonical
> Tavonni system has 4 gas giants, I originally thought it would be cool to
> make Tavonni a moon of a Large GG ("Ryzel") - at least until someone (Alvin
> Plummer?) pointed out the radiation problem if I wanted a "shirt-sleeves"
> world. He suggested changing it to a Small GG instead.
> ----------------------------------------------------------
> David "Hyphen" Jaques-Watson ..at.. Beowulf Down (Tavonni/Vilis/SM 1520)
> http://www.tip.net.au/~davidjw
> "I file things in historical order, with a hashing algorithm of gravity"
>
>
All of them have radiation fields strong enough to kill us - the trick is to be outside the radiation belts. Jupiter's big moons are all within its magnetosphere, which is why it's such a problem there. Titan orbits just outside Saturn's magnetosphere (so most of Saturn's major moons are within it), and Uranus and Neptune's big moons are within their planet's magnetosphere too.
Dr Ganymede wrote:
>All of them have radiation fields strong enough to kill us - the trick is
to be outside the radiation belts.
I put Tavonni at orbit 125 from Ryzel.
Actually, I've just noticed that I haven't updated Ryzel to a Small GG. Is
orbit 125 far enough out from a Large (100,000km) GG? I'm guessing that
Habitatatatatat (at orbit 8) is w-a-y too closeto really be an Ag world,
despite rolling it up using Bk 6 rules... ;-)
I also cheated, putting Ryzel at (solar) orbit 8.4. From memry, that's to
give Tavonni a reasonable climate. Of course, the next thing will be someone
telling me that Tarlac really isn't a G6 II star (mag -2.44), and that it's
changed in the Marches errata...
--> Tavonni World Views
--> RICE Paper #SM-1520: Tavonni/Vilis
--> System Details
----------------------------------------------------------
David "Hyphen" Jaques-Watson ..at.. Beowulf Down (Tavonni/Vilis/SM 1520)
http://www.tip.net.au/~davidjw
"I file things in historical order, with a hashing algorithm of gravity"
The primary factor here is that while Saturn is a large gas giant (size 75), its mass is 3.33 times smaller than Jupiter (size 90). Titan, at 20 units out is therefore well outside the area where radiation would be an issue. Rhea at 9 units out would probably experience some radiation effects, but not nearly what might be encountered at similarly placed Europa around Jupiter.
It would theoretically be possible to have a "shirt sleeve" moon in orbit around a large giant, but not close in (I'd argue anything less than 25 units out is dicey).
That said, Earth-like moons are a sci-fi staple, so we'll continue to see them in Traveller, Star Wars, Star Trek, etc. but unless what we know about moon formation around gas giants is totally wrong, habitable gas giant moons that aren't tiny water worlds should be a very rare bird indeed.
I've got numerous issues about habitable moons around gas giants - I've summarised them in a post on SFRPG because it kept coming up: http://www.sfrpg-discussion.net/phpBB3/viewtopic.php?f=30&t=2660&p=30238 http://www.sfrpg-discussion.net/phpBB3/viewtopic.php?f=30&t=2660&p=30238
And wow, a G6 II star? Change that to a size V, stat!