[Space] Baseline Universe

[DaltonS]

Originally Posted by David Johnston2

Suppose you were going to run an (interstellar) Space game. Or in fact are.

What would your Tech Level be?

Late 9 for humans (early nanotech and AI disasters have retarded development in those areas), early 10 for most aliens. Although human physicists continue to claim that gravity control is "right around the corner", spin gravity is still used for long duration space vessels and stations.

Originally Posted by David Johnston2

Would you have spacefaring alien rivals to humanity or just genetic variants of humanity?

Aliens are known but not common. While health oriented genmods are common, environmentally adaptive ones are not. (the meme is "We don't need to make aliens of our own people.")

Originally Posted by David Johnston2

What would be your preferred propulsion model?

As a long time fan of Babylon 5 I've always been fascinated by their "Jumpgate" technology, which in GURPS terms most closely resembles a Jump Gate described on page 19 of GURPS Spaceships. The main differences between GURPS and Babylon 5 hyperspace seem to be;

1. the need to "open a jumppoint" to enter and exit hyperspace,
2. the ability to loiter at the same relative position to the nearest strong gravity well in normal space without power (subject to gravitic drift), and
3. the ability to detect other ships and maneuver relative to them and fixed hyperspace landmarks (ie. "jumpgate beacons").

Hyperspace Physics
As the above characteristics seemed to make dramatic sense in Babylon 5, I decided to incorporate some of them in my personal hyperspace rule set, with a few variations.

• It is impossible to enter hyperspace where the gravitational stress on normal space is greater than 0.0001G. In the Sol system, this occurs at 2.45 AU or 1,223 light-seconds from the sun. This minimum safe distance (known as the "hyperlimit") can be found for other systems by multiplying the above numbers by the mass (in solar units) of the nearest star. A planet's hyperlimit (which need only be calculated for worlds that orbit outside the star's hyperlimit) is
  1. 100 earth radii times its mass (in Earth units) or,
  2. 50 times its diameter times the square root of its surface gravity in Gs
  from its core.
• Sensor range is reduced in hyperspace, giving a -2 penalty to all active or passive sensor rolls. While the range of radio communications is similarly affected, even at interplanetary distances there is no time lag detected; the speed of light in hyperspace is close to infinity (thus relativity does not apply).
• The gravitational fields of stars shunt a small portion of their energy into hyperspace. While the range of detection is relatively short (no stars beyond thirty parsecs can be detected), this does provide a simple method for hyperspace astrogation. (Note: the apparent radius of a star in hyperspace is its hyperlimit.)
• When a sensitive observatory was set up in hyperspace to extend this range, certain odd transitory signals were detected in the neighborhood of several of these stars. At first this puzzled the astronomers, but the mystery was quickly solved when a technician noticed that the profile of these signals exactly matched the one generated by a Hypergate when it opens and closes.
• A vessel entering or leaving hyperspace creates an electromagnetic pulse (EMP) in both universes, adding the vessel's SM to any sensor rolls to detect the event. This pulse is too brief to detect at interstellar distances.
• Direct realtime communication between normal space and hyperspace is impossible except through an open Hypergate, and even that requires a lasercom because the boundry effects of the event horizon scramble any radio signals. Because of this, some high traffic systems might find it more efficient to have two Hypergate stations; one in normal space for outgoing traffic and one in hyperspace for incoming ships. Military hypergates may be built in hyperspace to watch for approaching vessels.
• When a ship jumps back to normal space near an open hypergate, the power requirements of the requirements of each goes down for a moment. For one second (the length of the ship's jump to normal space) the energy consumed is multiplied by d/(d+r) where d is the distance between the ship and the event horizon of the gate on the hyperspace side, and r is the radius of the gate. This is called the Proximity Effect.

Hyperjump Rules
The general characteristics of Stardrives and Jump Gates used in this setting are as follows:

1. The minimum size of a vessel that can jump to hyperspace on its own is 10,000 tons (SM+10). This is also the minimum capacity of a stable Jump Gate requiring a minimum of one SM+13 system.
2. The base FTL-1 velocity (or "hyperspeed") of a Stardrive (also known as a Hyperjump Engine) in hyperspace is 0.2 parsecs/day. Ships too small to enter/exit hyperspace on their own (SM+9 or smaller) may do so through a Jump Gate (see below). Other names used for the Stardrive system are Jumpdrive or Hyperdrive depending on whether the ship is or is not Jump capable.)
3. For some odd reason, newtonian reaction drives do not work in hyperspace, so Rotary Reactionless Drives (known as "thrusters") are required for hyperspace STL manuvering. Since these drives cannot be used at the same time as the Stardrive, power can be diverted from one to the other. Ships using neither drive system remain stationary relative to normal space (see item "b" above).
4. Ships at hyperspeed cannot adjust their heading directly, so the ship must disengage the Hyperjump Engine, adjust the ship's heading with thrusters, then re-engage the Hyperjump Engine on the new heading to make course corrections.
5. Hyperjump Engines SM+13 or larger may be designed to be reconfigured into Jump Gate systems so that hyperspace capable auxilary vessels may be used.
6. Hyperspace Jump Gates (usually called Hypergates) open a "door" to hyperspace 0.5x(square root of total tonnage capacity) yards in diameter. The gate must recharge for 60 minutes between uses and will remain open for two minutes or until a mass exceeding its rated capacity attempts to pass through it (whichever is less). Multiple gate systems in the same ship/station may operate independently at staggered times to allow a smoother traffic flow.
7. Because of the Proximity Effect, the closer a ship is to an active Hypergate in normal space (ie. d<0) when it jumps to hyperspace, the more power it will take. Fortunately this is fairly easy to avoid, as the gate is only active for two minutes out of every hour. What would happen if a ship tried to jump in normal space between event horizon and gate radius (ie. -r<d<0) isn't clear, but best estimates indicate the energy released would destroy both ship and gate ... a real "bonehead maneuver" unless you want to use a "fireship" to destroy an enemy gate.

Originally Posted by David Johnston2

How far in the future would it be?

Early to mid 22nd century.

Originally Posted by David Johnston2

Why would be good.

"Breakout" occurred in the middle of the 21st century when the development of Rotary Reactionless Drive led to the discovery of hyperspace and the construction of the first Hypergate Station. I'm thinking of using the attempted invention of a "radiation screen" (modelled as a "drive field" effect of the thrusters) as the new starting point to my Hyperverse tech sequence (radiation screen => hyperdynamic field grid => rotary reactionless drive => "hypersink" cloaking => jump gate to hyperspace => hyperjump stardrive). If anyone is interested, I can post a more detailed timeline later. ;)

Dalton "who has a few ships on the drawing board" Spence