This section describes the way space travel is handled. It is a little technical in nature, but we suggest every participants reads it, to get an idea of what to expect on a space journey.
Orbits and speeds
Navigation in space is not so easy. Everything in the universe is moving. Celestial objects (planets and asteroids) are not at fixed locations, but all move in orbits around the sun. The speed an object orbits with is directly dependent on the distance to the sun. The farther away from the sun, the slower the object moves, as Johannes Keppler explained to us a few hundred years ago.
This means two things when you want to travel from one celestial object to another:
1. It is not sufficient to just bridge the distance between the celestial objects. If you don’t want to speed past your destination without being able to land, you will have to match your speed to the object’s orbital speed. Interplanetary space travel is not so much about bridging distances, but about changing speeds.
2. The distances between celestial objects are not constant. Two objects can at one moment both lie on opposite sides of the sun (with a huge distance between them), but on another moment lie behind each other in a straight line on the same side of the sun (where the distance is relatively small).
In the SevCol system, there are three ways to travel in space. Almost always, the third way, via jumpgates, will be used. However, we will also explain the other two ways, as they help with understanding the problems of interplanetary travel.
The first way is through so-called transfer orbits. This means that a spaceship makes all the necessary speed gain directly at departure, turns off its engines, and coasts further until it reaches it’s destinations orbit; it will have the correct orbital speed at this time. The required speed gain should be calculated exactly beforehand, and departures can only be made at specific times, when the objects have the correct distance to each other (these times are called Launch Windows). Furthermore, traveling through transfer orbits takes a very long time.
The second way is to keep the engines running during the entire trip. The ship will actually accelerate more than necessary for its destinations orbital speed, and needs to slow down again at its destination. This way of traveling is much faster than using transfer orbits, and it is also much less dependent on launch windows. However, this takes an awful lot of energy.
Since the 21st century, however, there is a third way of traveling through space, and this is the way the spaceship will be using.
Gravity Plates are very thin plates of a certain ceramic alloy, which generate a local gravitational field. They are used in all space ships, stations, and extra-terrestrial settlements where gravity is less than 1 G. If you are on a spaceship, you will experience a continuous earthlike gravity for your whole trip. Even if the ship accelerates quickly or turns sharply, you will not feel this movement due to the gravitational field of the plates
Besides generating artificial gravity, gravity plates can also be used for other things. By placing a collection of gravity plates in a particular geometric shape, the gravitational fields can reinforce each other. If this form is properly focused on an existing, large gravitational field (like the Sun’s gravity), a kind of artificial black hole emerges, which punches a wormhole through the space-time continuum. If there is another artificial black hole at a certain distance, along the same gravity vector where the first hole is placed on, then it is possible to fly a spaceship through this wormhole. It is thus possible to use gravity plates to make jump gates, with which you can jump to higher solar orbits. When arriving at this orbit, the ship will automatically have the correct orbital speed, because the jump gates orbit the sun like other celestial objects. For local maneuvering, when orbital speeds are not relevant, impulse engines will be used.
Jumpgates are very convenient, but they have some quirks. They radiate or reflect nothing; gravity pulls everything towards them. Therefore, it is very hard to detect a jump gate with ship-based sensors. Generally, jump gates are fairly stable, but sometimes a jump gate suddenly implodes; scientists are still not completely certain why this happens, although it has been discovered that jump gates that are close to each other are more likely to implode. Most jump gates are placed on a comfortable distance from other jumpgates, a distance which takes about half an hour to bridge in a spaceship. Furthermore, the wormhole connection between two jump gates is somewhat uncontrollable. A jump gate will generally connect with the nearest jump gate on the same gravity vector, but sometimes another connection is set up; this somewhat chaotic behavior is still not well understood. Last but not least, jumpgates have cool-down period. If a jumpgate is used in a certain direction, travelling into the reverse direction is not possible due to the buildup of gravitational radiation. Travelling into the same direction is still possible, but the gravitational radiation will have to dissipate before the direction can be reversed .
Interplanetary travel in SevCol
Interplanetary travel therefore consists of flying a path through a series of jumpgates to your destination. These paths are not fixed. As jumpgates orbit the sun just as other celestial bodies do, their position and connection to other jumpgates will constantly change. A navigator will have to plan a route based on the current positions of the jumpgates and of the destination. Also, when a ship has exited a jumpgate, the navigator will have to find the next jump gate and lead the ship to it.
Jumpgates are mostly placed about half an hour flying from each other. These regions of space between gates are called sectors. Sectors can be totally empty, but can also contain a variety of different things. Repair and supply stations and trading posts have been established at strategic locations in the jump gate network. Mining outposts on asteroids can also be found. Pirates roam space, and will use certain sectors to set up ambushes. These things can not be detected before a jump gate is passed. The distance that is bridged by the jumpgate wormhole is too big for normal ship sensors. The only way to determine what is present in a sector is to jump to it.
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