Star Map

[Henchman99942]

I wasn't super wedded to any specific size of space. I just wanted room for a handful of races to have a dozen or three habitable systems apiece. I don't think EVERY system should have a planet capable of supporting life. Any ratio or percent that I can think of seems way too high to me. I wanted a more sparsely populated larger region. I also plan to use a tramline system that only connects certain types of stars... the mechanism that produces the tramlines requires specific types of stars. I didn't realize that we were so limited in our star maps today. We need to send out space probes so we can get a better view of our local area. Even a light month or two should provide enough parallax for a much more accurate measuring. But this is fiction, so I could live with 'best guesses' on some of the more distant ones. I just wanted to use Sol and those stars in our area to lend a sense of reality and place to the campaign, rather than making up a random map and using an alien setting. I was surprised at how few G types are actually in our neighborhood. This makes me think useful systems would be even more rare.

I appreciate the links provided. I am stilling looking through them, and I have found stuff that I can use. Mostly, game play will take place in a space station, but I did want some star travel. I tend to put a lot of work into the background of the setting that the players don't really even encounter. But my brain doesn't allow me to play fast and loose with things like facts and reality. So I can't get rolling unless I do enough fact checking and I can convince my brain that everything makes sense, even if only with regard to my own particular brand of sci-fi pseudo-science.

[Fred Brackin]

Originally Posted by Henchman99942

II didn't realize that we were so limited in our star maps today. We need to send out space probes so we can get a better view of our local area. Even a light month or two should provide enough parallax for a much more accurate measuring. .

The issue isn't distance of observatories to conduct the measurements, it's time to do all of them. You're wanting data on 100,000 stars or more.

Also, the thing you're wanting to collect the data is far more complicated than a "probe". It's a full-fledged telescope in the range of IRAS if not quite Hubble. It'll be a long time before those can go without being remote-controlled from the ground.

[ericbsmith]

Originally Posted by Henchman99942

I didn't realize that we were so limited in our star maps today. We need to send out space probes so we can get a better view of our local area. Even a light month or two should provide enough parallax for a much more accurate measuring.

One of the biggest problems with observing our own galaxy is how obscured the objects we're trying to observe are - much of our own galaxy is hidden behind the dust and debris that makes up the galaxy itself. We're sitting in the middle of a galactic arm, and looking out across the galaxy is a lot like trying to observe the far side of a sand box while being buried in the sand yourself, there's just no line-of-sight that allows you to observe some of the material without going hundreds of light years above the galactic plane (getting above the sand box, as it were).

Originally Posted by Fred Brackin

Also, the thing you're wanting to collect the data is far more complicated than a "probe". It's a full-fledged telescope in the range of IRAS if not quite Hubble. It'll be a long time before those can go without being remote-controlled from the ground.

If you want to see just how difficult this can be just look at the life, death, and resurrection of the Kepler Space Telescope, which was set in a heliocentric orbit some distance from Earth. These are very complex machines with a lot of moving parts that must survive for years in a hostile environment without maintenance. When something on them breaks NASA will attempt to work around it as best they can, but as more things break they must eventually write off the loss and shut down the mission. The further these satellites are from us the harder it can be to diagnose the break-downs (it's hard enough working on a computer that is 15 minutes of communication away, such as the Mars landers; trying to do so on one that's 15 weeks of communication away would be maddening).

[Flyndaran]

Originally Posted by Henchman99942

... I was surprised at how few G types are actually in our neighborhood. This makes me think useful systems would be even more rare....

While planets orbiting G types are the most likely to have earth like life, that doesn't make it impossible for small F or large K types. It's certainly possible for terraformable planets to exist around nearly any star not insanely hostile from atmosphere blasting high energy radiation.

[ericbsmith]

Originally Posted by Flyndaran

While planets orbiting G types are the most likely to have earth like life, that doesn't make it impossible for small F or large K types. It's certainly possible for terraformable planets to exist around nearly any star not insanely hostile from atmosphere blasting high energy radiation.

Even M type Red Dwarf stars are not out of the question to have earthlike planets. Given the sheer numbers (85% of stars are Red Dwarfs), it's virtually guaranteed that a few will have habitable worlds. While most planets around an M star would be tide locked, it's possible for one to be locked into a 3:2 lock, the way that Mercury is, which would give it long days but at least even out the heat and make it liveable. Also, since M stars are so long lived, if a planet can be stable they can literally have 10-11 billion years of existance (the Earth, by comparison, is only about 4.5 billion years old, and you probably need a couple billion years after the big bang for stars to generate and disseminate the heavy elements that can form earthlike worlds).

[Damon Griffin]

Originally Posted by ericbsmith

In the US we all know there are 50 states, but does anybody here know how many cities there are in the US? I sure don't. I can estimate that there are probably 10-20 cities in each state, which gives a range of 500-1000 cities

As of 2015 there were 19,505 US locations incorporated as cities. But 16,470 of those had populations under 10,000; I presume you were counting those as towns, villages, etc. but even so that leaves over 3,000.

Still, I cannot imagine any Earth-US based RPG requiring information on all 3,000+, much less all 19,000+, so your point is well taken.

[johndallman]

Originally Posted by Henchman99942

I didn't realize that we were so limited in our star maps today.

The Gaia observatory is gathering the data to improve things. Digesting it will take some years.

[Phantasm]

In my own space opera setting, which has a "settled" area of a 20 ly radius around Sol and a "frontier" out to 50 ly, I've discovered the following K, G, and F systems which may be suitable for extrasolar Garden planets: Alpha Centauri A, Alpha Centauri B (both 4.3 ly), Ran (nee Epsilon Eridani, 10.5 ly), Procyon (11.4 ly), 61 Cygni A, 61 Cygni B (both 11.4 ly), Epsilon Indi (11.8 ly), Tau Ceti (11.9 ly), Groombridge 1618 (15.9 ly), Omicron2 Eridani (16.5 ly), Sigma Draconis (18.8 ly), Gleise 570 (19.3 ly), Eta Cassiopeiae (19.5 ly), J. Hershel 5173 (19.7 ly), 82 Eridani (19.8 ly), and Delta Pavonis (19.9 ly).

Two nearby A-type stars are also of interest: Sirius (8.6 ly) and Altair (16.8 ly). These may not house habitable planets - or even planets in general, particularly Sirius with its white dwarf companion - but they may be strategic locations, and certainly of scientific interest.

Of the M-type stars, Proxima Centauri (4.2 ly) and Barnard's Star (5.9 ly), being the closest, will be visited early on and have well-mapped systems. Others are likely to be hit-and-miss. If humans (and/or other races) in your setting have a "if there's a planet or asteroid belt, we've got a station there!" mentality, like they do in mine, sometimes it may be best to just say, "well, if the players visit there, I'll at least have an asteroid base, a Stanford Torus, or O'Neill colony there, which I'll name on the fly...". YMMV on that, of course.

[Flyndaran]

Originally Posted by ericbsmith

Even M type Red Dwarf stars are not out of the question to have earthlike planets. Given the sheer numbers (85% of stars are Red Dwarfs), it's virtually guaranteed that a few will have habitable worlds. While most planets around an M star would be tide locked, it's possible for one to be locked into a 3:2 lock, the way that Mercury is, which would give it long days but at least even out the heat and make it liveable. Also, since M stars are so long lived, if a planet can be stable they can literally have 10-11 billion years of existance (the Earth, by comparison, is only about 4.5 billion years old, and you probably need a couple billion years after the big bang for stars to generate and disseminate the heavy elements that can form earthlike worlds).

I agree, but how many "a few" is is not something we can even reasonably guess at. I will say that I don't see how a carbon cycle could last 10 billion years, liquid core induced magnetic fields, tectonic activity, etc. All things important, if not required, for earth like planets.
On the other other hand, space faring peoples don't need a gem world to be perfectly earth like on its own. It would actually be harder to live on one with its own ecosystem just as complex and resilient as Earth's.
Alien worlds with oxygen atmospheres and ONLY cyanobacteria type life would probably be the easiest to fully terraform, in my opinion.

[ericbsmith]

Originally Posted by Flyndaran

I agree, but how many "a few" is is not something we can even reasonably guess at. I will say that I don't see how a carbon cycle could last 10 billion years, liquid core induced magnetic fields, tectonic activity, etc. All things important, if not required, for earth like planets.

The carbon cycle is largely regulated by life itself. Assuming that life on such a planet reaches an equilibrium instead of going out of control and creating a hellish greenhouse or frozen iceball it could go on indefinitely. The liquid core, and resultant magnetic field and tectonic activity, is easily explainable with tidal forces of a planet in a 3:2 tide lock with it's star. Or, alternatively, by having an earthlike planet as a moon of a gas giant which happens to orbit in the habitable zone of the star.

Originally Posted by Flyndaran

Alien worlds with oxygen atmospheres and ONLY cyanobacteria type life would probably be the easiest to fully terraform, in my opinion.

That's probably true, though virtually any planet with an atmosphere is probably relatively easily terraformable by the time you reach TL 11 or 12 bioengineering. You are right about trying to colonize already flourishing worlds, though, unless you're using the fast-and-loose biology and physics usually seen in any science fiction that actually deals with setting foot on alien worlds.