Engage Stardrive!
Space is vast. It is in fact so vast that our minds have trouble grasping it.
The nearest star to our own is Proxima Centauri, 4.3 light years away. There are two others, Alpha Centauri A and B, close to it. By astronomical terms, this is actually quite cramped. Nevertheless, it would take a conventional spaceship 80 years or so to get there. Even within our solar system, it takes light 1.3 seconds to reach Luna. The same light could circle Earth 40 times in one second.
Most sci-fi settings solve this problem by having a spaceship engine that cheats conventional physics in some way. You either go very fast while light effects play beside you, or your ship teleports in some fashion. This article is vaguely based on the concept of the Wormhole Induction Propulsion, or WHIP drive, which is a real theory proposed by Dr Eric W Davis of the National Institute for Discovery Science. Basically, the theory states that it's possible to create a stable wormhole and travel through it to another part of the universe.
This article will deviate from the theory in a few important ways, however. Therefore, I will not use the term "WHIP drive," but rather the more conventional "stardrive."
Distances and Scales
Light years are a common way to express distance in space. However, I will use parsecs (pc), which is the SI unit (International System of Units). Besides, it sounds more sciencey. One parsec is 30.857e15 metres, or 3.262 light years.
For in-system distances, I will use astronomical units (AU), which is a measure of the "average" distance between Earth and the sun. One parsec is 206,265 AU. One AU is 149,600,000 km.
For Scale purposes, I will use the Starship Scale introduced in Building the Better Spaceship by Elliot Schutjer. Using human-based scale on spaceships is just silly.
The Principles
There are four principles at work when engaging a stardrive.
a) The drive requires a power source of megalithic proportions to generate the required magnetic field. Therefore, engaging a stardrive is a rather costly affair. An appropriate power source is an anti-matter reactor or an enormous laser array, for instance. The reactor must provide a burst of energy, which will generate an appropriately powerful magnetic field. A high-energy laser creates a massive magnetic field when it passes through a dense plasma, which can be created by the laser itself. Such a power source simply needs an amount of raw material to vaporize into plasma.
b) Upon activating the stardrive, a wormhole throat will appear. This throat can range from small (enough to admit one ship) to gigantic (enough to admit an entire fleet). A larger throat will require more power.
c) When the wormhole exit is placed, the destination point will deviate from the intended target by a proportion of the distance travelled. This means that you can reach your target more or less spot on if travelling only a parsec or two, but will almost certainly end up far away from your destination on an intergalactic jump.
d) The wormhole can only be open for a certain amount of time, depending of the strength of the magnetic field. In general, a small wormhole can be maintained proportionally longer than a larger wormhole on the same power source. When the magnetic field is gone, the wormhole will collapse, and once established, the field cannot be reinforced.
How to apply this in game terms
Fudging a Wormhole
People wanting to use a stardrive will need an Astronavigation: Stardrive Operation skill. This is the ability to find one's way in space and of tuning the stardrive just right for one's purposes.
Wormholes will have a Scale, just as the individual ships do. Ships attempting to enter at the same time cannot have a combined Scale greater than that of the wormhole. For example, if two Scale 2 ships enter a Scale 6 wormhole, they will have plenty of room to spare, but if a Scale 3 corvette wants to join, one of them must wait.
Scale 0 ships are so small that they can slip in between the larger ships, though not in unlimited numbers. The GM should use sense in deciding this.
The wormhole is powered by a magnetic field, which cannot be reinforced once the wormhole is open. What this means is that it can only be maintained for so long. A stardrive will have a Duration trait on a normal Fudge scale. A Duration of Terrible means it can only admit one ship. Poor means it can let through two ships in a row, and so on. Legendary wormgates should be reserved for the crumbing remains of an ancient, yet advanced civilization or the like.
A wormhole's magnetic field will be generated by some sort of power source, which will contain a number of charges. Depending on the type of stardrive, it might or might not have the ability to recharge. If it does, the stats will say how long it takes to recharge the power source for another jump.
Stardrives will also have an Accuracy trait, and this is where the real distinction comes into the picture. Every time a jump is attempted, two rolls must be made: The operator must roll a Stardrive Operation check, and the stardrive an Accuracy check, against the following values:
| Distance | Difficulty | Example |
|---|---|---|
| Assuming a starting point of Earth | ||
| In-system jump | Poor | Mars, Jupiter, Quaoar |
| < 10 parsecs | Mediocre | Proxima, Sirius, Spica |
| 10-100 pc | Fair | Arcturus, Capella, Canopus |
| 100-1000 pc | Good | Antares, Rigel, Deneb |
| Intergalactic | Great | Neighbouring galaxies, LMC |
| Intergalactic | Superb | Distant galaxies, M81 |
If both these checks succeed, the ship will emerge at some point not too far away from where the intended destination was (the longer the distance travelled, the greater the deviation). If one fails, it will mean the exit is a fair bit off the mark, and will probably require a second jump to correct it. If both checks fail, either a gross miscalculation or a space-time anomaly has thrown the wormhole exit wildly off the mark, and it will require an Stardrive Operation check even to realize where it is. The distance will be about right, but the ship will have taken a completely different direction at some point. Intergalactic jumps will likely end up in the deep, dead space between galaxies.
Remember that interstellar jumps are very rarely accurate. Depending on the stardrive, it may be necessary with more than one jump to reach the target even on a successful initial jump. For the same reason, it's better to have one large wormhole than several smaller ones when transporting more than one ship. Even the best stardrive operator can't get it exactly right at such distances; the physical limitations on the technology are too great.
Adding a Bit of Crunch
Some GMs might feel that these rules are too abstract for a hard sci-fi setting. For them, I present here a more detailed approach:
Wormholes still have a Scale. Similarly, magnetic fields have one, which tends to be rather larger than that of the wormhole. This is because the wormhole can be maintained for a number of clicks equal to field Scale minus wormhole Scale. One click equals the time it takes to admit one Scale 1 item; a Scale 4 cruiser would spend 4 clicks. Scale 0 ships are so small that they take a negligible amount of time; however, the wormgate must still be open for at least one click. Again, the GM should use common sense.
Power sources will have a capacity and a max field rating. The max field rating signifies how large a magnetic field the source can generate in one go; the capacity shows how much energy can be spent in total before it is depleted. An antimatter reactor with capacity 60 and a max field rating of 10, for instance, will be able to generate six Scale 10 magnetic fields before it has to be be refuelled.
Wormgates and stardrive-equipped ships will have a max wormhole rating as well. This is the maximum Scale of the wormhole generated. A small wormgate equipped with the aforementioned 60/10 reactor might have a max wormhole rating of 6. This will allow it to create a Scale 6 wormhole for 4 clicks, or for instance a Scale 2 wormhole for 8 clicks. It will just barely admit a colossal Scale 5 freighter, but leaves two Scale 3 corvettes plenty of time to pass.
In place of an Accuracy trait, the Stardrive will have a number for this purpose. This is expressed as a negative power: 10e-8, for instance, means that the deviation from the target will be 0.00000001 of the distance travelled. Travelling from the Milky Way to M81 - a distance of approximately 4,000,000,000 pc - will result in an average deviation of 40 parsecs. Closer, but still a considerable distance from the intended destination!
When attempting an in-system jump - that is, from place to place within the same star system - the exit throat will be more or less spot-on if the navigator rolls a Stardrive Operation of Good or better. Even a Terrible result will only lead to perhaps an AU of deviation, which nevertheless is quite a trek on a conventional drive.
For interstellar jumps, a successful roll will place the exit throat at about the expected deviation for that stardrive. A remarkably good roll will place it closer, and a Terrible roll will result in the same as two failed rolls in the simple rules.
Ships and Wormgates
In civilized parts of the universe, most jumps will probably be performed by using wormgates. They are large, stationary installations capable of creating wormholes big enough for several ships. They will almost certainly draw power from a renewable source, and be maintained often, and manned by a skilled crew. Their main advantage is that they can admit several ships at a time. If each of the ships had an individual stardrive, they would likely end up very far from each other.
"Jump-ships" can also be used for this purpose; however, they have the disadvantage that they themselves must go through, and therefore must keep the wormhole stable for longer.
An in-ship stardrive will almost always have just enough of a maximum field rating to transport that particular ship. A Scale 4 ship will have a stardrive capable of generating a Scale 4 wormhole with a Terrible Duration. Power reserves might be enough for more than one jump, but then again might draw from the same source as the conventional drives. The stardrive accuracy will depend on the vessel's purpose: High for an interstellar explorer or capital ship, low for a shuttle or in-system freighter.
Although a stardrive comes in very handy for an independent explorer, it does take up a lot of room. In most explorer vessels, the stardrive takes up more than half the ship.
Examples of Stardrives
Wormgate Drive
These belong to large, stationary facilities that see a lot of use. Size is generally not a factor, but its magnetic field generator needs to be renewable. For this reason, most wormgates use arrays of high-powered laser or maser cannons and solar panels for power.
The gate itself is usually a ring-formed aperture in which the wormhole throat is formed. The ring needs to be large; it varies in size from stupendous to mind-boggling. Just the material technology is a challenge, as large structures tend to wobble and break from the tension.
Single Ship Drive
Ships that travel to other parts of the universe for exploration or military reasons cannot rely on wormgates, but have to have internal stardrives. The up side is that you don't have to take all kinds of ships into consideration, just the one you're travelling in. The down side is that large laser cannon arrays aren't practical anymore, and you have to use more portable, and therefore expensive, methods.
The drive consists of several extensible arms with superconductive coating, a jump core, and some kind of front shielding. When preparing for a jump, the ship extends its arms so they form a ring the size of the wanted wormhole throat. A charge is then detonated in the jump core - basically a shaped nuclear or antimatter blast which provides the needed power burst to form the magnetic field. This is why the front needs to be shielded.
Jump Ship Drive
A jump ship is essentially a portable wormgate. It can allow a lot of other ships to pass through the same wormhole, and is usually only practical in military context. There are three kinds: Ones that build a smaller, but stable wormhole, ones that themselves are built like a ring, and ones that can connect to others of the same kind for a larger aperture.
The first kind are essentially only equipped with a more powerful single ship drive, and larger dimensioning arms. The ship builds a wormhole, passes through itself, and then leaves it open for others to follow. Needless to say, jump ships of this kind tend to be quite large vessels.
A more uncommon kind is the ring-built one. They tend to build larger, less stable wormholes, and can allow other ships to pass through inside itself. These ships tend to have less mass, however, and can therefore not carry as many jump charges. This limiting factor tends to make them less popular. In these cases, setting the Scale of the ships can be a bit tricky. One might be tempted to give them a large Scale, well, because of their large scale, but remember that a) they tend to be flimsy structures, and b) other ships are supposed to pass through their wormholes at the same time.
Those which connect to form larger rings, however, are another story. They typically consist of an oversized laser array, a fusion power plant, and some form of conventional drive. The shape is in most cases slightly curved, and several of these ships interlock to form a wormgate ring. There is a minimum number of ships needed to generate a suitable magnetic field, usually six. Large fleets can make use of twenty ships or more.
51 Pegasi Wormgate
This is an example of a wormgate. The facility is located at the Langragian point L1 relative to the planet orbiting 51 Pegasi, a G5 class star a little more than 15 parsecs from Earth. The planet itself is a gas giant orbiting very close (0.05 AU) to its parent star, and is home to a gas mining company operating under hellish conditions. Gas from the refinery is transported in gigantic Scale 8 tanker ships, mainly to the Lambda Serpentis system.
The wormgate itself is a free-floating installation with a substantial crew. It faces the relentless sun, and so requires heavy shielding to keep from overheating. It activates fairly often, and so has a large solar panel array for recharging the four high-powered maser cannon arrays it uses for generating a strong enough magnetic field. Its batteries can sustain two jumps when fully charged. However, because emergency jumps might be necessary, the batteries are never drained below what takes to power up the wormgate once. Solar panels recharge the batteries at one charge every four Earth days.
The docking ring is capable of handling quite large vessels, but is a far cry from the military wormgates in the Sol system, which can move entire fleets. Its aperture can accommodate Scale 8 wormholes, which is sufficient for the tankers it services.
Crewing the wormgate are 12 experienced stardrive engineers. They have worked together for a long time, and are Good stardrive operators. When attempting a jump to the Lambda Serpentis system, however, they can be trusted to do a Great job. They get a lot of practice traversing that particular distance, after all.
The stardrive aboard the wormgate is somewhat ageing, but nevertheless does the job. It's an old model of Mediocre Accuracy, which, on the 21 pc jump to Lambda Serpentis, will usually place the voyager within a few AU of the destination. The wormgate engineers have petitioned for a Fair upgrade, but so far their request has been denied on grounds of not being able to generate enough immediate returns. There's middle management for you.
| Stats Summary - Fudgey | |
| Power source | 2 charges, recharges 1 in 4 days |
| Aperture | Scale 8 |
| Duration | Poor |
| Accuracy | Mediocre |
| Stats Summary - Crunchy | |
| Power reserves | Scale 35, recharges 4/day |
| Power source | Scale 16 |
| Aperture | Scale 8 |
| Accuracy | 10e-6 |
Bibliography & Further Reading
- "Wormhole Induction Propulsion (WHIP)"
- "Building the Better Spaceship"
- Astronomical Distances, at scienceworld.wolfram.com
- Langragian point, at Wikipedia
