So, I've been quiet a lot lately, due to family necessities such as required computer down-time and such. But I've been active nevertheless, working on a new scifi rpg setting. This is almost just an exercise of my world building skills, but I think it's becoming worthy of at least a campaign.
The next few entries will discuss the setting topic by topic. The first one, this one, is a general introduction.
Post-Terra
The setting is circa 1 500 years to the future. In AD 2544 Earth was destroyed by a massive impact damage. The cause of this was a giant asteroid sent off-course by meddling humans trying to prevent a far-future impact. Several fragments of this asteroid, successfully destroyed by humans, slammed into the moon, sending it spiralling towards Earth.
Evacuations started over 60 years before the impact by UN-headed project Daedalus. However, a scientific breakthrough made FTL travel possible through generated wormholes. An operation to control this technology was unsuccesful and the technology soon leaked ti the world, leading to an uncontrolled diaspora of humanity with everyone who could afford offsystem travel doing so.
Most opted for nearby systems which had some habitable systems. Some, however, made the hard choice and started a long voyage accross the interstellar void for the Cruxis zone, the largest area of habitable life in the galaxy. The Cruxis zone is over 40 000 ly from Earth and is roughly 1200 ly in diameter.
This story is about those brave who successfully made it to the Cruxis zone, known to it's inhabitants today as "known space".
After settling on several promising worlds, humanity once again reached for the stars. Within a few hundred years interstellar trade was flourishing and even the occacional skirmish was seen between the rising stellar nations. Most of these fledgeling colonies controlled only one or a few systems and centered on a single starsystem, but some rose to control more than a hundred systems and inhabiting dozens of planets.
There are of course species native to this zone. The Garm are marsupial sentients who are psychologically quite close to humans. There have been a few wars between the human nations and the Garm but mostly trade and diplomacy have been the key. Garm have been content to stay in their sphere of stars and humans have been content to stay on theirs. The Tanz, named after their discoverer, the Macedonian ship Tanganjika, are silicate-based lifeforms who live amongst the humans, mainly near cooling systems and engines of starships. They work as repairmen and technicians and have a knack for computer hacking. Then there are the Others, the Arachnids or however one might call them. They look nightmarish but their requirements for life are different enough from humans that they do not compete from the same worlds as humans do. Some human-controlled systems may have Other colonies on their outer planets but mainly the two don't interact much.
Technology is based on manipulation of gravity, fusion power and ftl travel. There is no ftl radio, so news travel by courier ships. Gravity technology is used for stl drives, force fields and on-planet building technology. Countergrav cars were experimented upon but they caused more trouble than what they were seen worth and were abandoned. Thanks to gravitic technology, no spin gravity is required on starships or space stations to generate gravity. Thanks to inertial compensation, ships can handle over 100G acceleration rates and military vessels can do even 200-300G. The huge power consumption of these systems are met by advanced fusion power. Most ships have at least two reactors giving the ship ample energy for all needs. Due to the larger consumption rates, the fusion reactors need to be fueled roughly once or twice a year. They use hydrogen and helium as fuel, both being equally acceptable.
The FTL technology works as follows: it can be activated only around the outer limit of a given system, around 15-50 AU from any star. The FTL drive spins up, generating a temporary wormhole between A and B. Systems A and B must be in straight-line connection not going through the system of departure (within the system limit). Currently the technology can maintain only a 4-5 parsec (12-16 ly) wormhole so a cross-zone voyage may well be around 150-200 days of travel, depending on route choice. Interstellar space wormholes are known to be highly inaccurate and unstable so most sane people avoid opening wormholes in interstellar space. Navigation and endpoint calculation is a science known as astrogation and is fairly complex but manageable by a human of sufficient training.
Pre-jump sequence takes around 5-15 minutes. During this time the ship spins up the jumpdrive and shuts down other systems to give the jump maximum accuracy. The astrogator inputs the jump coordinates and the onboard navigation computer makes corrections due to constant travel and After-jump the jump drive needs to cool down for a duration of 1h per travelled parsec after which a new jump can be made. A jump can be detected through gravitic sensors as it generates quite a bit of localized gravitational phenomena. This effect can be devastating up to 1000 km away from the ship entering or leaving and this effect can be seen up to 15 AU away from the jump point. Because of the vast area to cover, detecting incoming jumps is done mainly by deep-space sentry drones who send a warning to the centralized system command through laser pulse.
In my next entry, I will discuss more of the existing major starpowers and write something about the average lesser powers around.
Näytetään tekstit, joissa on tunniste rpg. Näytä kaikki tekstit
Näytetään tekstit, joissa on tunniste rpg. Näytä kaikki tekstit
tiistai 14. huhtikuuta 2009
sunnuntai 26. lokakuuta 2008
Sublight Travel
This one has bothered me for a while in my game setting and some others as well so I'll write up my thoughts here and try to sort it out.
So, let us assume that there is a way of working FTL which works with speeds of about 0,3-0,5 parseks an hour. It's drawback is that it doesn't work well in a gravity well. Previously I had specified that the limit a ship could approach an object in space was about 100 times the diameter of the object multiplied with it's surface gravity (a cheap ripoff from Traveller, I know). With average settled planets in this setting this would be about a million km.
Now then, concerning gravity wells, the largest in a solar system would naturally be the star(s). With our dear Sol this would be about a million kilometers, making it's base jump limit around 100 million kilometers, just short of Earth. However, when multiplied with the surface gravity of 27g this would create an almost 2,7 billion kilometer no-jump zone, about 18 AU, roughly around the orbit of Uranus.
Now, this makes interstellar travel a bit more slow. While it takes a few hours to make the jump from, say Alpha Centauri to Sol, it still would take quite a while to make the travel from Uranus to Earth on sublight. At light speed it would still make about two and a half hours to reach it.
Until now I've ignored the effect of the Sun in this, limiting myself only to planetary gravity wells but after doing a little study for another project of mine I realized that I cannot do this without proper explanation. It's paradoxical, isn't it? Why take some wells into account and not others? Are stars somehow different than planets, would this be a question of, say, densities? Star densities are way less than planetary densities, even Saturn is more dense than the Sun. It would make a more simple explanation to include the Sun gravity well into the accounts as well.
So, let us now consider the two models of gravity well jump limits with the stl technology available. Previously, starships were doing about 2-3 g tops, most ships around 0,5-1g. Courier ships and such might break for 8-10g but that would be it. That would mean that a 1g acceleration ship would accelerate to around 9,8 m/s squared. Let us say that fuel limits cap this acceleration to a delta-vee of 30 km/s. Travel from Uranus to Earth would take almost three years. Not really viable as I thought that the absolute travel time to a world 10 pc away would take about a day. Outer system colonies and stations would boom as trade hubs though, as merchant ships would want to minimize the travel time and just dump the cargo, get paid and leave. And faster in-system ships would then take the trade items further in-system.
Now then, ignoring the effect of the sun, a starship would appear around 1 million km from Earth. With 1g acceleration and a 30km/s delta-vee the ship would take about 9 h 15 min not including deceleration to reach Earth. A bit long still but more viable. In Earth's case, having stations in lunar orbit would be profitable since ships would then prefer to dock at the much nearer moon stations, leave the cargo there to the middle man and leave.
However, I thought a different solution. Increase the acceleration so that ships in-system would travel at around 0,1-0,3c. The solution I thought of is gravity drives which would be almost like warp drives in themselves. This would still make the travel from Uranus to Earth a long travel, around 12,5 hours on the average 0,2c speed, not including deceleration. With gravity compensators onboard (a technological item already included in the setting), inside the ship people would not notice the acceleration much. Which is good, since the planned 50-200g acceleration would squash a crew in an instant to tomato juice. I've planned that the grav drive would take it's power from fusion reactors onboard. This would however make smaller fighters less effective because of the space reactors require. Smaller ships would be mainly for maintenance, supply runs and crew transfer. On the other hand, ships built for battle would be huge.
This creates another problem. I've always liked the setting's emphasis on heroic fighter pilots fighting amongst large battleships and swarming the bigger ships with missiles. Emphasizing bigger ships would however make rebellions a much harder thing to do without orbital support and when the Imperial Navy kicks in, it's over. Then again, even a well-equipped fighter squadron defending a world would be doomed since the Imperial Navy has it's own fighter squadrons to deflect such attacks. And of course clever tactics will always be an advantage.
The appeal of having a large system to travel through before arriving at the inner system inhabited planets is largely of the chances of action along the way. While the journey of a million kilometers to a jump point might include some exitement, fast ships could intercept the pirate attacking around the jump limit and it is a little risky running that close to the planetary security. Not profitable. With a couple of light-hours to travel there might be "accidents" and the patrol is far away..
I'll have to think and see where this goes.
So, let us assume that there is a way of working FTL which works with speeds of about 0,3-0,5 parseks an hour. It's drawback is that it doesn't work well in a gravity well. Previously I had specified that the limit a ship could approach an object in space was about 100 times the diameter of the object multiplied with it's surface gravity (a cheap ripoff from Traveller, I know). With average settled planets in this setting this would be about a million km.
Now then, concerning gravity wells, the largest in a solar system would naturally be the star(s). With our dear Sol this would be about a million kilometers, making it's base jump limit around 100 million kilometers, just short of Earth. However, when multiplied with the surface gravity of 27g this would create an almost 2,7 billion kilometer no-jump zone, about 18 AU, roughly around the orbit of Uranus.
Now, this makes interstellar travel a bit more slow. While it takes a few hours to make the jump from, say Alpha Centauri to Sol, it still would take quite a while to make the travel from Uranus to Earth on sublight. At light speed it would still make about two and a half hours to reach it.
Until now I've ignored the effect of the Sun in this, limiting myself only to planetary gravity wells but after doing a little study for another project of mine I realized that I cannot do this without proper explanation. It's paradoxical, isn't it? Why take some wells into account and not others? Are stars somehow different than planets, would this be a question of, say, densities? Star densities are way less than planetary densities, even Saturn is more dense than the Sun. It would make a more simple explanation to include the Sun gravity well into the accounts as well.
So, let us now consider the two models of gravity well jump limits with the stl technology available. Previously, starships were doing about 2-3 g tops, most ships around 0,5-1g. Courier ships and such might break for 8-10g but that would be it. That would mean that a 1g acceleration ship would accelerate to around 9,8 m/s squared. Let us say that fuel limits cap this acceleration to a delta-vee of 30 km/s. Travel from Uranus to Earth would take almost three years. Not really viable as I thought that the absolute travel time to a world 10 pc away would take about a day. Outer system colonies and stations would boom as trade hubs though, as merchant ships would want to minimize the travel time and just dump the cargo, get paid and leave. And faster in-system ships would then take the trade items further in-system.
Now then, ignoring the effect of the sun, a starship would appear around 1 million km from Earth. With 1g acceleration and a 30km/s delta-vee the ship would take about 9 h 15 min not including deceleration to reach Earth. A bit long still but more viable. In Earth's case, having stations in lunar orbit would be profitable since ships would then prefer to dock at the much nearer moon stations, leave the cargo there to the middle man and leave.
However, I thought a different solution. Increase the acceleration so that ships in-system would travel at around 0,1-0,3c. The solution I thought of is gravity drives which would be almost like warp drives in themselves. This would still make the travel from Uranus to Earth a long travel, around 12,5 hours on the average 0,2c speed, not including deceleration. With gravity compensators onboard (a technological item already included in the setting), inside the ship people would not notice the acceleration much. Which is good, since the planned 50-200g acceleration would squash a crew in an instant to tomato juice. I've planned that the grav drive would take it's power from fusion reactors onboard. This would however make smaller fighters less effective because of the space reactors require. Smaller ships would be mainly for maintenance, supply runs and crew transfer. On the other hand, ships built for battle would be huge.
This creates another problem. I've always liked the setting's emphasis on heroic fighter pilots fighting amongst large battleships and swarming the bigger ships with missiles. Emphasizing bigger ships would however make rebellions a much harder thing to do without orbital support and when the Imperial Navy kicks in, it's over. Then again, even a well-equipped fighter squadron defending a world would be doomed since the Imperial Navy has it's own fighter squadrons to deflect such attacks. And of course clever tactics will always be an advantage.
The appeal of having a large system to travel through before arriving at the inner system inhabited planets is largely of the chances of action along the way. While the journey of a million kilometers to a jump point might include some exitement, fast ships could intercept the pirate attacking around the jump limit and it is a little risky running that close to the planetary security. Not profitable. With a couple of light-hours to travel there might be "accidents" and the patrol is far away..
I'll have to think and see where this goes.
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