A Layman's Guide to Drive Technology
Paper By Yosef Ismail, Master Professor of Astrophysics, Gerim National University.
This paper is intended as a guide to drive technology as it pertains to astrophysics in the simplest sense, as drive science is a large and complex field touching on many different scientific disciplines. Not all areas of Jump Field science are yet fully understood and as such this guide may change in future revisions.
Starships are the workhorses of interstellar commerce, moving goods and sophonts from one star system to the next. At the heart of every starship is the power plant, providing the power to run all the ship's systems, from life support, the computer and sensors to the maneuver and jump drives that move the ship through space. Hydrogen fuel is converted into the energy required to power the ship’s systems by the power plant. Hydrogen fuel can take two forms, refined fuel, or protium, the most common isotope of hydrogen with one proton and no neutrons; or unrefined fuel such as hydrogen gas from gas giants or water from worlds or ice asteroids. Unrefined fuel tends to contain varying amounts of contaminants that can interfere with the operation of the drives.
Starship drives start to become truly economical with the discovery of fusion power. Once a stellar civilisation develops the ability to build fusion drives space travel becomes relatively cheap and efficient. When available, fusion power plants become the driving force behind stellar travel. Over the thousands of years that sophonts have travelled the stars, power plant designs have become more efficient and more compact, but the basic principles of the fusion power plant have changed little.
Not so with the maneuver drive, the component that moves ships through the space between worlds. Before the development of fusion plants maneuver drives often just mixed hydrogen and liquid oxygen and ignited it to produce thrust. After the development of fusion power these crude rockets were typically replaced with ion drives, mass drivers, nuclear thermal rockets, and even fusion rockets. It is not until the basic structures of the universe are fully understood that gravitic drives can be developed.
Early attempts at gravitic drives produced the grav drive, engines that pushed (or pulled) against gravity wells to produce movement. However that was their shortcoming as once they were outside the typical field of most gravity wells they became ineffectual. Later developments produced thruster plates, which are a combination of gravitic and damper technology. Manipulating the basic components of the universe allows thruster plates to generate the required movement, thus making them usable even outside of a gravity well, and making them the first true universal reactionless drive.
The key to developing this technology is, as I stated before, the understanding of the basic structures of the universe, in particular the cause of the 100 diameter field effect. As you all know mass is the measure of a quantity of matter - how much of it there is. Weight, on the other hand, is the effect that gravity has on that stuff. So weight depends on the strength of a gravity well, while mass does not.
The vast majority of mass in the universe cannot be detected by visual means, but its presence can be detected by its weak gravitational field and the effects it has on visible matter. This gravitonic matter, which is smaller than standard atoms, and visible material are often found clumped together due to their mutual gravitational attraction in most regions of the universe. Gravitonic matter most often consists of photinos, axions, sterile neutrinos, neutralinos and gravitinos(1). As these particles do not interact with electromagnetic forces or visible matter they can pass through each other without slowing down substantially.
The only interaction is caused by gravitons, the supersymmetric partner of the gravitino. Surveys of gravitonic matter have found densities vary from equal amounts up to 100 times as much gravitonic matter as visible matter, although on average the ratio is usually twice as much gravitonic matter to visible matter in our galaxy. Early methods to detect gravitonic matter included galaxy rotation curves, gravitational lensing, and structure formation calculations. Current gravitronic sensors can give us detailed and precise charts of gravitonic matter distribution.
Given that gravitonic matter and visible matter interact via gravity it stands to reason that they will tend to clump around each other. Gravitinos in particular, while passing through visible matter, interact with gravity wells causing them to slow and clump. Hence we see the field effect of gravitonic matter around gravity wells. This clumping of gravitinos decreases with the cube of the distance from the centre point of the gravity well, similar to the regular tidal force of gravity. The majority of this clumping therefore occurs inside the 100 diameter field of the gravity well.
Now knowing about gravitonic matter does not make it useful in producing maneuver drives. Many sophont races discovered the existence of gravitonic matter and yet could not harness its energies, relying instead on grav drive technology. It is only with the discovery of the graviton particle that thruster plates become even theoretically possible. Once the existence of the graviton is proven, gravitonic energy can then be used as a means of propulsion.
Given knowledge of the graviton the basic concept of thruster based M-Drives is quite simple, and is very similar to an electric current passing through various conductors. By changing the 'spin' of the gravitons between gravitinos the M-Drive causes a flowing effect of gravitons in one direction. This flowing effect has the advantage of dragging the M-Drive along with it, as well as whatever is attached to the M-Drive. More powerful M-Drives, with denser thruster plates, are able to increase the rate of gravitonic flow and thus increase the velocity of movement. This same flowing effect is used to create artificial gravity on starships.
Grav plates create a localised field that causes gravitinos to flow around them, while attracting visible matter to produce local gravity and (mostly) negating inertia. As the technology for building M-Drives advances civilisations seek to produce denser and more efficient thruster plates. Maneuver technology tops out at thrust 6 and it is usually at this point in their technological development that civilisations will start experimenting with rare earth elements such as Lanthanum to break the thrust 6 barrier. Historically, this has almost always resulted in the destruction of the drive and the ship as a hole is torn in Jump space, exposing the ship to Jump space energies.
Generally most civilisations do not realise that this event is the first discovery of Jump space. Just prior to the explosion a huge surge of gravitonic energy is detected around the ship. The first assumption will almost always be that the explosion is caused by gravitational stresses. In actual fact the graviton surge causes, and is caused by, the tearing of the Jump space energy interface. It is theorised that the reverse spin on the graviton becomes so violent in the presence of Lanthanum that it causes the fabric of space-time to rupture, exposing Jump space, however this has never been proven concisely.
Further research into this problem will always result in the civilisation moving away from gravity wells to microgravity environments to reduce these gravitational stresses. If a civilisation persists with this line of research then eventually it will discover that by projecting a shell of hydrogen around the test ship the graviton surge can be deflected away from the ship, thus preventing its destruction. When the ship vanishes in a flash of Cherenkov radiation the researchers will naturally assume it has suffered a catastrophic drive failure, however after a week the ship will usually reappear from Jump space nearby the research facility.
Further research will follow eventually leading to controlled in-system jumps. It is during this time of jump drive development that the 100 diameter field is proven, although it is usually not fully understood how this effect ties into Jump space. What is now known is that the hydrogen bubble has a lubricating effect on the passage into Jump space, preventing the gravitinos from sealing the breach in time-space. This allows a ship to pass through the breach without being torn apart by gravitational stresses. The hydrogen bubble has the additional benefit of protecting the ship from Jump space energies.
Why this occurs is unknown at this point in time as any attempts to measure Jump space energy results in the destruction of the measuring equipment. What is known is that inside the 100 diameter field the density of the gravintinos begins to become so great that the hydrogen bubble cannot form correctly causing a distorted insertion into Jump space. Usually at the 10 diameter field point the gravitinos are so dense the hydrogen bubble cannot form at all and with no protection from Jump space energies the ship will almost always instantly be destroyed as soon as the jump tear is formed.
These early primitive in-system jump drives were useful in exploring solar systems, however interstellar travel is generally difficult until the development of Jump 1 drives. It is at this point I must mention that most Dimensional Theorists propose that Jump space is a multi-dimensional universe having different layers which correspond to different jump distances(2). These in-system jump drives seem to 'skim' the border between Jump space and normal space. An interesting effect of this boundary between normal space and Jump space is that it is not until starships go over 100 displacement tons mass that they can fully pierce this Jump space boundary.
A quick description of Jump space entry is needed at this point. Hydrogen fuel is pumped into the jump drive to super-cool the Lanthanum grid while at the same time the power plant feeds power into the storage capacitors of the jump drive. Once the capacitors reach about 85 percent capacity the extra hydrogen fuel needed is pumped into the jump bubble component of the jump drive. The jump bubble is generally formed just before the jump capacitors reach full charge. This energy then dumps into the Lanthanum grid, repelling all nearby gravitinos and causing the graviton surge that tears open the hole into Jump space.
The hydrogen jump bubble then keeps the gravitinos repelled long enough for the starship to 'drop' into Jump space. If the starship displaces more than 100 tons mass then it can 'breach' into Jump space otherwise it will 'skim' Jump space for an in-system jump. The more power used in creating the 'breach' into Jump space the deeper into Jump space the starship will be inserted. Given the vector of the insertion and the power used to push the starship into Jump space gives a jump of the desired destination and distance.
The final portion of energy in the jump drive is used to attract the gravitinos back into the 'breach' in normal space to close the Jump space tear and sever the starship's ties with normal space. Jump space physics then seems to act on the starship like a bubble in water, no matter how deep into Jump space the ship goes it will always pop out of Jump space after the typical 168 hours +/- 10 percent(3). The hydrogen jump bubble then allows the starship to 'breach' back into normal space. Research has shown that even if you point the jump exit point within the 100 diameter field around a gravity well the clumping of Gravitinos will always force the exit point 'breach' of a starship back out to that 100 diameter range.
Research continues into building more efficient and powerful drives. Some types of mis-jumps seem to prove the existence of deeper levels of Jump space. Anti-matter drive research is starting to look like a promising source of power needed to drive starships into these deeper levels of Jump space for longer jumps. However, until stable anti-matter drives are developed, fusion drives will continue to power the fleets of starships that move across the depths of known space. Research also continues into the possibility of breaking the M-Drive thrust 6 threshold in a fashion that doesn’t result in the tearing of Jump space.
(2). There is also some research that points to a connection between Jump space and pocket universes.
(3). 'Type 2' and 'Type 4' mis-jumps are a known exception to this rule.