Drive Technology

Toposophic Level and Drive Technology

The type of ship and ship propulsion or drive used has varied greatly throughout the history of human colonisation of space. In general, the toposophic level required to develop, manufacture and control the various drives is the largest determinant of the power, capability, and usefulness of the drives.

The lowest sophont level known to produce capable space drives is S:0, the ubiquitous modosophonts. Representative S:0 drives are adequate for intrasystem purposes and can even make short interstellar journeys up to perhaps a dozen light years on a regular basis. Heavily optimized modosophont hybrid designs are even more capable than that, able to reach a notable fraction of c (the speed of light; an ultimate speed limit for anything that has mass) and have a practical range approaching 100 light years.

Higher sophont levels have vastly greater capabilities, as noted in more detail below.

Early in history, space was thought to be an empty void. The ancestral humans of Earth, as they struggled to reach space, developed equations for the effort that assumed space to be nothing. These are the ancient rocket equations still taught today, even though they only apply to the low speed regime of space travel, used only for short ranges and by the Deepers.

As we all know, space is not nothing. As more and more experience was gained in space travel at higher and higher energy levels, it became obvious that space was not empty, and had structure, together with resources and hazards.

Over the many millennia of the Terragen expansion, long-distance space travel has become routine, and several broadly defined regimes of that travel have become widely recognized.

1) Low Speed
In general, low speed interstellar travel is anything below 0.3c. The upper boundary of the low Speed regime is the point where the interstellar medium can be gathered effectively via ramscoops. At 0.3c and below shielding requirements are not nearly as rigorous, effective maneuvers can be taken in extreme cases, and space travel is generally quite easy. The vast metaempire of the Deeper Covenant is by far the largest user of this regime of space travel, and large numbers of sophonts and considerable amounts of material  move between the worlds using this regime.

2) High Speed
In broad terms, high speed interstellar travel falls in the regime between 0.2c and 0.84c. The relevant boundaries of this regime at the lower end is the point at which optimised ramscoops can obtain significant mass flows, and the upper boundary is the point at which relativistic mass effects make further ram-powered acceleration impossible even with total conversion drives.

3) Relativistic
In broad terms, this is the regime above 0.84c in which relativistic effects dominate. The beneficial effects of this regime are heavy time-dilation effects and it's just plain fast. The down sides are the very high energy requirements and the extreme shielding measures required.

4) Spacetime Structural
In broad terms, this regime is defined by modifying the space-time the craft is traveling through, allowing the vessel to move through space as a result of this modification. It is also possible to use this structural deformation of space-time to protect the craft. Only transapients at the S6 level can design and create craft which use this structural deformation reliably as a form of propulsion.

In general terms, S:0 technologies can reach only Low Speed and into the High Speed regimes. S:1, S:2, and S:3 technologies can reach the High Speed and into the bottom of the Relativistic regimes. S:4, S:5, and S:6 technologies can reach the High Speed, Relativistic, and Spacetime Structural regimes.

A note on ship construction practices: Many examples are quoted below for S:0 drives that give ranges of specific impulse (Isp), delta-v, and thrust-to-weight ratios. A word of explanation of these terms is required:

Specific Impulse is a common measure of how much thrust you can gain for a given length of time using a given mass of fuel.

Delta-v (Δv) is the total amount of acceleration and deceleration (which is really just acceleration on a different vector) which a ship using this drive can achieve. For simplicity, only "reasonable" mass fractions are explored: It is possible to get very  high delta-v figures for any drive if you devote 99.99999+ percent of the ships mass to fuel. In general, all the examples quoted assume no more than 90 percent of the ships initial mass is fuel, and many of the examples assume no more than half. Indeed, the ancient and famous "Clippers" of the Amat Age were based upon half the ship's mass being fuel. Of course, any external or very large source of fuel (ramscoops and void bubbles, for example) make such allowances meaningless.

Mass-To-Weight ratio is the weight of the engine only versus the thrust the engine produces. At modosophont levels, this is an important measure, but at S:>1, it becomes much less important.

The oldest and simplest, and still used for many tasks, are chemical rockets. These are useful only for short journeys. Interplanetary ships use electric and ion plasma propulsion, nuclear fission and fusion pulse ships, internal fission drives, lightsails, anti-matter-initiated fusion, and various types of external pulsed plasma. Some of the more common variants are discussed briefly below:

S:0 chemical rockets typically fall into three broad categories, cryogenic, stable, and hybrid.

Chemical cryogenic rockets use fuels that demand active storage measures in almost all star systems if used inside the "snow line." By far the most common such system is the liquid hydrogen/liquid oxygen rocket, which uses plain water as fuel, split into its component elements.Such rockets typically have Isps of 400 to 500 seconds, a thrust to weight ratio of less than 100 to 1 and a total delta-v of no more than 10 km/sec.

Chemical stable rockets use fuels that are stable in most star systems up to or beyond the inner region of the habitable zone. Most such are also solid fuel rockets, although not all. One of the most common such fuels is aluminum powder and a non-cryogenic oxygen or fluorine source. Another popular version uses lithium and a non-cryogenic hydrogen source. Such designs typically have Isps of 200-400 seconds, a thrust to weight ratio of less than 80 to 1, and a total delta-v of no more than 8 km/sec.

Chemical hybrid rockets use fuels that are cryogenic and non- cryogenic in combination. There are many reasons for such choices. Typically, the solid fuel component is chosen such that it can serve as insulation for the cryogenic one. Some popular combinations are aluminum powder and liquid oxygen, or lithium and fluorine. Such designs typically have Isps of 500-600 seconds, a thrust to weight ratio of 120 to 1, and a total delta-v of no more than 12 km/sec.

More on Chemical Rockets here

These are possibly the simplest space drives of all: take a mass of any volatile (water and ammonia are both popular), seal it in a balloon, and heat it by putting it inside the local snowline. Add a nozzle, and instant rocket. Such designs have  Isps usually no more than 200, a thrust to weight ratio of 1000 to 1 or better, and a total delta-v of no more than 5 km/sec or so.

These include the classic "ion drives" of ancient myth. Capture incident photons from a nearby star, convert them to electricity, and use the electricity to fire ionized reaction mass. Such designs have Isps of 400 to 2000, a thrust to weight ratio of 0.001 to 1 or less, and a total delta-v of 30 or more km/sec.

More on Ion Drives here

These oddities use chemical lasers as their drive mechanisms. The most common of them use the chemical exhaust as rocket exhaust as well, and have terrible performance, not appreciably better than regular chemical rockets. Such designs  usually have Isps in the 300-400 range, a thrust to weight ratio of 20 to 1, and a  total delta-v of 15 km/sec or so. An uncommon variant is the stellar chemical photonic drive, a hybrid that uses lasing reactants that can be regenerated by the light of the local star. Such designs have a very low thrust to weight ratio but very high delta-v (for the S: level) similar to a lightsail, but have the advantage that the thrust can be directed in any direction. Such designs typically have Isps of 9000 or more, a thrust to weight ratio of 0.0001 to 1, and a total delta-v of 100 km/sec or more.

Passive Propulsion

The greatest drawback of the reaction driven rocket, whether it derives its energy from chemical reactions or antimatter, is the need to carry its own fuel and propellant on board. To avoid this, various kinds of passive propulsion have been developed, from the basic solar (stellar) sail which uses the light pressure of the local star for propulsion, to the more advanced laser driven concepts, which use powerful stationary lasers based for propulsion. Laser propelled craft can be simple sails, or the laser beam can be used to heat propellant which is expelled to provide thrust. Other concepts such as the magsail use a magnetically constrained cloud of particles as a sail surface,.

More powerful still is the particle beam concept, or Beamrider, which uses a collimated beam of particles with mass to transfer momentum to the craft. This is the basis of the interstellar Beamrider Network, established by the Deeper Covenant long ago.

More about Beamriders here

The stellar sail and beamrider should not be confused with the Drivesail concept, which is a reactionless drive that uses exotic spacetime properties to provide thrust. 

These designs and the external pulse drives are the real workhorses of the S:0 world, assuming a good supply of their rare fuel can be obtained. Fissile and fertile isotopes are very rare in Population 2 stars, but fairly common in Population 1. In very young or very active star-forming regions, many usable isotopes may be common,but in most star systems, only three isotopes are available, U235, U238, and Th232. Hydrogen or ammonia is the most commonly used reaction mass with these drives. The performance envelope for these drives is very broad, and almost completely determined by the sophistication of the internal shielding available. The lowest performance drives use centrifugally contained solid cores, and need relatively little internal shielding as they are quite cool.
Hotter still are the liquid core designs, usually but not always centrifugally stabilized. In liquid-core designs, the temperature of the fuel increases until it melts. The most common fuel composition is a uranium-iron alloy, U6Fe, which has a very high vapor pressure and boiling point but a fairly low melting point. Liquid  core designs use high temperature "normal" or nano materials such as early diamondoid as the containment, actively cooled by blowing reaction mass through the containment.

Even hotter are the vapor core designs, in which the fuel is in the form of a gas,  usually uranium fluoride of various compositions such as the U, F, UF4, UF6 family. Chlorine and thorium can also be used with similar performance and chemistries. Such designs are also usually centrifugally stabilized, with complex counterflow gas currents in the core. In early designs, the containment is usually diamondoid in a porous structure, actively cooled by blown reaction mass. This type of active cooling is more effective in a vapor core design due to the single-phase gaseous core. In more modern designs, the diamondoid is usually supplemented by reflective programmable matter layers. Some vapor core designs also begin the use of electromagnetic shielding to supplement the diamondoid/programmable matter vessel.

Last are the fission plasma core designs, in which the gaseous core becomes hot enough to partially or fully ionize the gas to a plasma, and the use of electromagnetic shielding becomes essential rather than an addition. Plasma core fission drives are the distant ancestors of the much more potent Monopole Catalyzed Conversion Drive, and the work on containment vessels done for these plasma-core devices is critical for early Conversion Drives, as well. Such drives use a complex multi-layer design of electromagnetically cooled plasma, a blown-in gas layer (usually the reaction mass) and a diamondoid/programmable matter last wall.

Internal fission drives have Isps ranging from 800 seconds for a simple solid core design to 8000 seconds for an advanced plasma core design. The thrust to weight ratio ranges from 10 to 1 to 100 to 1, and the total delta-v varies from 20 km/sec to over 100 km/sec.

More on Fission Drives here

Such designs, along with the internal fission drives, are the workhorses of the S:0 world. EPPs avoid the difficult shielding problems of the Internal drives by moving the "drive chamber" completely outside the ship. Such designs are extremely wasteful of fertile, fissile, and fusion fuels, meaning internal drives have some competitive advantages, but since they do not need to contain the full power of the drive reaction, they can have a very high performance envelope for their S:level.

Typically, early designs use simple fission devices to generate plasma pulses. More  advanced designs use fission/fusion staged pulse units, antimatter catalyzed fusion pulse units, antimatter boosted pulse units, and rarely, antimatter pulse units. The performance of the designs are mainly constrained by the material strengths available. Early ships using fission pulse units and simple steel acceleration disks typically have Isps around 5000, a thrust to weight ratio of 5 to 1, and a total  delta-v of 60 km/sec. A middle-ground ship using antimatter-initiated pure fusion pulse units and a primitive diamondoid  acceleration disk typically has an Isp around  20,000, a thrust to weight ratio of 20 to 1, and a total delta-v of 180 km/sec+. An advanced antimatter-boosted (1 percent) fusion pulse unit design with an electromagnetically shielded nanotech-based programmable matter acceleration disk typically has an Isp around 100,000, a thrust to weight ratio of 100 to 1, and a total delta-v of 800 km/sec or higher.

Extremely wasteful and dirty even compared to the external pulse plasma drives, external fission/fusion drives are hybrids between internal fission drives and EPPs. They essentially move the fission drive outside the ship, but do not use pulse units, instead generating a constant fission or fission/fusion reaction. The thrust is transferred to the ship via an electromagnetically shielded programmable matter acceleration disk. Due to the constant burn, a very good shielding system is needed, at least as good as the best used for the internal drives, but since the reaction is not contained, much higher power levels can be tolerated, with similar high performance.
Indeed, such designs have higher power levels than either EPPs or internal fission  drives, as the cost of enormous fuel consumption. The one outstanding feature of such a design is the tremendous thrust and acceleration levels possible, making such drives popular with S:0 military organisations. The most primitive of these use pure fission reactions and electromagnetic/diamondoid acceleration disks. More advanced versions use electromagnetic/nanotech acceleration disks and fission/fusion reactions. The most primitive of these designs has an Isp of around 30,000 seconds, a thrust to weight ratio of 200 to 1, and a total delta-v of 200 km/sec. The most advanced, using fission-fired D-D fusion reactions, has an Isp of around 1,000,000 seconds, a thrust to weight ratio of 300 to 1, and a total delta-v of 5000 km/sec.

More on Fusion Pulse Drives here

Internal Fusion driven freighter

Internal Fusion Drives

Such devices are the follow-on drives of the internal fission drives, assuming once again that a good supply of their rare fuel can be found. They also serve as the ancestors of the first antimatter drives. There are many fusion reactions possible with S:0 technology, but only one is really well suited for space travel, that being the fusion of He3 to He3. Other candidate reactions such as p-B11, He3-D, D-T, and D-D all have large levels of neutron production. While nanotech self-healing shields with programmable matter elements can effectively shield against  these neutrons, such  shields are very heavy indeed. He3-He3 is the least neutron-producing reaction available to an S:0. Sadly, He3 is rare even when it can be found at all, and the best sources, large gas giants, have very large gravity wells. Fissile fuels are also rare, but can be found on small rocky worlds, planetoids, and asteroids. The ignition conditions for fusion reactions are also much, much higher than for fission reactions, so it is common for internal fusion drives to carry small amounts of fissile material to use as "seeds" to ignite the more potent fusion reactions. Such igniters are called "fissile pits" for ancient reasons. (Indeed, even the super advanced Conversion Drives of the Archai still carry such fissile pits, and for the same reason.) These fissile pits serve the same use as matches used by modosophonts. Even the mightiest fire needs the first spark to ignite it, and for most drives, that spark comes from fissile pits.

Fusion drives always use very advanced nanotech based internal shielding, with a layer of "cool" plasma closest to the active plasma, a layer of gas vapor outside the cool plasma, and a nanotech solid outer wall, with electromagnetic shields running on the solid outer wall and plasma inner "wall." Such internal shields are similar to those used by advanced fission internal drives. Internal fusion drives have an Isp usually between 1,000,000 and 3,000,000 seconds, a thrust to weight ratio of 30 to 1 or better, and a total delta-v of 30,000 km/sec or maybe more, if the extreme mass fraction required can be tolerated. As a note, 30,000 km/sec is roughly equal to 0.1c, and thus internal fusion drives are the first drives to even potentially have use as interstellar drives.

More on Fusion Drives here

Antimatter Catalysed Fusion Vessel

These drives are the ultimate possible for S:0 technologies. All practical antimatter drives are internal drives, as antimatter is far too expensive to use in a wasteful manner. Antimatter is rarely found in nature, and always very thinly spread in the vacuum of space as a byproduct of high-energy processes. The harvesting of such space-borne amat is rarely economically viable. For most purposes antimatter has to be manufactured from pure energy, a difficult process indeed. Antimatter is also difficult and extraordinarily dangerous to store. The only reason early modosophonts were compelled to endure the extreme difficulties with it at all was the truly incredible performance it offered compared to fusion, and the fact that antimatter drives are the first practical interstellar drives. An antimatter drive is always used to convert matter directly to energy, and then that energy is used either as direct reaction mass, or to heat another reaction mass. In general, direct antimatter drives are by far the best performers and the only ones referred to as true antimatter drives, while intermediary antimatter drives are usually referred to as boosted fusion or antimatter catalysed fusion drives.

More on Antimatter Catalysed Fusion here

As a matter of fact, almost any boosted fusion drive can be run in a pure antimatter mode, and almost any antimatter drive can be augmented with some fusion fuel or other reaction mass. In general, boosting or not boosting a drive involves trading Isp for thrust. Drives used in gravity wells are usually heavily boosted, while drives used for deep space travel are usually run as pure antimatter drives. Boosted drives usually have Isps between 1,000,000 and 10,000,000 seconds, a thrust to weight ratio of 20 to 1 or better, and a total delta-v of 10,000 to 80,000 km/sec. Pure antimatter drives usually have Isps close to the maximum physics allows, 30,000,000 seconds, a thrust to weight ratio of 100 to 1 or more, and a total  delta-v of 150,000 km/sec. These last figures lead to the classic specifications for  the ancient "AMAT Clippers", namely, for a launch mass that was one quarter antimatter and one quarter reaction matter, you could reach 0.25c on both legs of a round-trip journey without refuelling. Adding a ramscoop to such a design improves the range and performance considerably, and such designs are the earliest ones to  break out of the Low Speed flight regime and into the High Speed flight regime.

More on Antimatter drives here, including the early Amat-Thermal Drive, the more advanced Pion Drive and the advanced Amat Torch drive

The most efficient S:0 drives are complicated hybrid designs meant for one-way trips. Such designs consist of an antimatter-powered ramscoop coupled with a lightsail. The flight profile consists of a laser boost phase to 0.2-0.3c, where the ramscoop gathers reaction matter for the antimatter reaction. The vessel boosts up to about 0.7c and coasts. To decelerate at the far end of the journey, the ramscoop is used for braking, combined with the lightsail used in a stardive maneuver and a small amount of remaining antimatter. Due to lack of effective shielding, such designs are sharply constrained by erosion to little more than 100 lightyears in range. This is about the best performance an S:0 design is capable of.

More on Ramscoop drives and associated technology here

The most advanced and efficient of the S:0 drives are the internal fission, internal fusion, and antimatter drives, all of which incidentally have the most sophisticated containment vessels. If a modosophont has a higher S: level patron, it is possible to modify these drives to be vastly more efficient. A simple gift of a microgram of permanent monopoles is enough to allow a modosophont culture to make more, and thus it is quite common to see conversion drive ships in the most developed portions of Known Space being used by citizens all the way down to S:0. In general, such ships are vastly less powerful and cruder than the S:1 prototypes or S:2 mature versions, but they work much better than even antimatter ships. Lacking magmatter containments or the advanced shielding of the higher S: versions still sharply limits their ranges, however. maximum speeds of 0.7c and ranges of a few dozen to a hundred
light years is still the norm, but now the ships can be refuelled and make round trips at that performance level.

Unfortunately, the discussions of the higher S: level drives below are necessarily vague. While the core operating principals of many of these drives are comprehensible to a trained S:0 mind, the nuts and bolts details of how the drives actually work require higher-level sentience to grasp. The indisputable existence of the Conversion Drives, Drive Sails, and the ineffable Void Ships is proof positive that however the Archai make them work, they do indeed work.

S:1 Technologies

Conversion Drives

Transapients beyond the first singularity, that is the S1 level, find it possible to manage the complex and exacting task of monopole manufacture; an important application of monopole technology is the matter furnace. A matter furnace uses magnetic monopoles to convert any matter directly to energy, usually in a catalyzed fusion plasma. Those magnetic monopoles which can be created by S1 are massless and have short lifetimes, meaning more must be constantly generated while the matter furnace is running, requiring large particle accelerators. While expensive, heavy, and complicated, such manufacturing equipment was still much lighter and cheaper than an equal mass of antimatter, as well as being much, much safer. Mounting a matter furnace on a ship creates the Conversion Drive, and such drives immediately began to dominate space travel. These drives convert matter to energy without the extreme expense and danger of antimatter. Early conversion drives are very large, yet have low power outputs compared to their more developed performance, mainly due to the need for monopole creation mass drivers and the continued use of plasma/vapor/solid/EM shielding systems. Such systems are the best possible at S:1, yet are barely up to the rigors of even low powered Conversion drives. S:1 Conversion drives have similar performance levels to the very best S:0 designs, but do not need the complicated multi-stage hybrid designs in order to reach them. Even better, since they are able to burn any common matter, they are far easier to refuel, meaning round trips at that performance level are quite possible.

The ease of refueling and the existence of useful ramscoop technology means that delta-v calculations no longer have much meaning. Similarly, ALL higher S: reaction drives have essentially the same Isp, the maximum allowed by physics, namely 30,000,000. In general, S:1 Conversion-ships have a maximum speed of .7C and a maximum range of 100 to 200 lightyears, mainly limited by the simple passive ablative shielding they employ. The Monopole Catalyzed Conversion Drive is such a huge advance, it almost completely displaces all previous technologies. There are still some Internal Fusion Drives built at S:1 and higher to take advantage of the very cheap fuel often available, and they are generally improved versions of their lower-tech ancestors, but fission drives and antimatter drives are almost completely abandoned.

More on Conversion Drives here

S:2 Technologies

At singularity level two, monopoles become much more common, varieties of monopoles are created that have permanent lifespans, and magmatter becomes possible as the properties (mass, charge, etc) of monopoles are much more refined and permanent monopoles can be manufactured in useful varieties and quantities. The large advances at S:2 include the advent of the first magmatter reaction chambers, which allow much higher energy levels to be achieved. magmatter is able to withstand nuclear-level temperatures and stresses without any cooling at all, and with advanced photo-electric cooling arrays can withstand temperatures and pressures many orders of magnitude greater than any matter available previously. This makes the magmatter reaction chamber the ideal companion to the permanent-monopole Conversion Drive. Permanent monopoles mean that the monopole creation equipment is no longer needed, making the Conversion Drives at S:2 much smaller and less complex, while the magmatter reaction chambers, even without cooling, allow much, much higher energy levels and densities to be achieved. Monopoles can also be included in the ramscoop (if fitted to the vessel) which boosts the efficiency of the scoop enormously, and the higher energy levels allow the first generations of active ship shielding, with pathfinder lasers and simple pebble fountains coming into wide use. This array of breakthroughs make true long-range, high-speed interstellar travel not only possible but practical for the first time at S:2.

These various improvements increase the performance of the Conversion-ships enormously, with steady cruising speeds up to 0.84c. The much improved active shielding systems allow ranges to reach 1000 lightyears, with full round trips possible.

Spacetime Catapult

Also at S:2, the advances in monopole creation enable the first of the reactionless drives, the Spacetime Catapult. These are the earliest of the Pitch drives, also called space tractors. The operating principal of these drives exploits the  reactionless properties of spacetime distortions in the vicinity of a massive spinning toroid. To make the principle work, the torus is constructed of a hyperdense magmatter superfluid, that also has to be compressible and have a high degree of internal cohesion, all while internal losses are minimized or recirculated. Such material is very challenging to make at S:2, and the rigors of the design process are speculated to be one of the triggers that leads to the development of both wormholes and void bubbles at higher S: levels. Such materials are generally called "supercritical hypermatter" and have many obscure uses besides use in Pitch Drives. Many upper S: devices use the topological properties of such materials in ways that modosophonts simply do not have the perspective to perceive, much less understand. These design points are so challenging that the design cannot be made portable, but the advantages of reactionless acceleration are so large that a way was worked out to use them anyway. Spacetime Catapults use several toruses in sequence, since each one has a fairly small gain. They are used to reactionlessly accelerate durable bulk cargo for interstellar delivery. Since they are designed for low cost large volume deliveries, they often don't operate at extremely high c fractions to reduce relativistic losses. A noticeable exception to this is where the receiving system uses a recuperating braking system, so the relativistic energy can be captured for local use. In those sorts of cases, the maximum speeds can reach very high fractions of c. Spacetime Catapults are widely used at 0.2 to 0.7c, more rarely at 0.7 to 0.84c, and occasionally at 0.85 to 0.95c. Their range is 20 to 2000 lightyears, with shepherd clades needed for any journeys over 100 light years or so.

More on Spacetime Catapults here; see also Herders

S:3 Technologies

At Singularity level:3 Conversion Drives are a mature technology, and they do not appreciably change in power output at higher S: levels. They do become much lighter and can have many useful effects added, such as exhaust tuning, reaction speed, and the like. The main advances at S:3 for interstellar ships involve the perfection of active defenses for high speed travel. As noted previously, space is not empty. Indeed, in some areas of space where the interstellar medium is especially dense between two or more large population wells, the skyways are positively clouded with swarms of interstellar ships. In general  terms, ramscoop-equipped vessels seek out the densest interstellar mediums, while  non-ramscoop ships travel through the thinnest areas. However, ALL vessels traveling in the High or Relativistic Speed Regimes have to be massively well defended against the deadly corrosive effects of the interstellar medium, not to mention the occasional lethal dust speck.

The most primitive S:0 ship shields are simple passive ablative shields, often simply a mass of water ice with diamondoid fibers running through it perched on the nose of the ship. Slightly more advanced shields have the shield mass split into halves, with a portion flying a few miles in front of the ship proper, so that massive dust hits have space for the energy released to dissipate. Modosophont ships do not have the energy needed for active shields and to reach high speeds.

At S:1, Conversion Drive technology allows much more power to be available, but the lack of permanent monopoles keeps electronic shields and ramscoops weak and short ranged, as mere superconducting electrons are sharply constrained in their abilities. This lack, and the imperfect state of programmable matter photonics, makes converting the abundant power available into a useful shield difficult. Thus, the shielding remains mainly passive, with magnetically levitated passive shields a few dozen kilometers in front of the ship being the norm. Such matter-based semi-active shields are commonly called "pebble fountains" or "vapor shields." At S:2, permanent monopoles allows enormously more energy to be available, and advances in programmable matter makes photonics also much more potent and powerful. This allows photoelectric cooling of the conversion drive to generate vast amounts of electricity, which is readily converted back to tuned photons at the front of the ship, leading to the development of the "pathfinder laser" the first truly active ship defense method. Using a pathfinder laser, the main forward shield of the vessel is no longer a  passive or active block of matter, it is a beam of high-energy photons. This light beam serves to ionize any gas or dust, allowing monopole-strengthened electromagnetic fields to be much more effective. The combination of the photons and the electromagnetics serve to enormously improve the defense possible compared to a passive block or ice or a simple pebble fountain.

At S:3, ship shielding methods reach maturity. The pathfinder laser becomes tremendously powerful and for the first time is integrated with active shielding pebbles using tiny lightsails that levitate inside the beam, along with ram field effects (if present) and levitated magmatter hoops for  photoelectronic/magnetic effects. Controlling such an array of actively flying units in such a way that the following ship is never exposed is a huge challenge, and requires the vast mind power and efficient modes of thought of an S:3 mind. Using these advanced, multi-layer shields, such Conversion-ships can reach steady-state cruising speeds of 0.88c (the improvement comes from high speed reactions in the mass-stream from the ramscoop, or improved mass fractions if not.) They can also sprint up to 0.93c to 0.95c, and have the shields to handle those speeds for very long distances even without a ramscoop. In addition, at S:3 enough computational power can be applied to the active shielding to allow very comprehensive shielding solutions, with the semi-autonomous 'pebbles' sailing on miniature light sails in the pathfinder laser. By using a levitated magmatter hoop for magnetic lateral braking, the pebbles can redirect some of energy of the pathfinder laser laterally in the space before the ship, either sweeping the area more efficiently or concentrating the mass more effectively.This effect, combined with long-baseline sensory arrays based in the pebbles and the extremely powerful magnetic fields possible with monopole enhanced electromagnetic shields allow the pebble fountain to provide effective shielding even to the side of the vessel.

In essence, the output of the pathfinder laser is directed forward, where there is a vast cloud of shield pebbles, each with a tiny grain of computronium, a basic sensor suite, and a small lightsail. The pebbles intercept the light and are kept from wafting way by the grip of the electromagnetic shields/ramscoop. A portion of the pathfinder laser is allowed to shine forward, where it acts to illuminate the ship's path so dust can be detected earlier and it ionizes the background gas. A portion of the light is focused sideways, to push gas and dust into favorable places for shielding or scooping, and a portion of the light is directed backward toward the ship, and in this reversed light, millions of pebbles sail sedately along, using their sensors to search in every direction. At least one layer of pebbles is arrayed between the ship and any possible vector of a dust collision. At the back of the ship, spent pebbles are directed into the hugely powerful drive beam, and they reflect a portion of that light also lateral to the ship, where it is re-reflected by the cloud of pebbles, making them more mobile. Pebbles along the side of the ship are kept from escaping by magnetic fields. More pebbles are created from mass scooped as the ship travels. This effective and 360 degree shielding combined with the high power levels allows such ships to have effective ranges of 1000 to 2000 light years.

More on shielding here

Pitch Drive

Also at S:3 the Pitch Drive is greatly improved. Even better magmatter control allows much better, denser, smoke-ring behavior, especially in the regime of compressibility and cohesiveness. This allows the smoke-ring torus to have much higher density differences between the inside and outside, while spinning even faster. These improvements increase the stability, power, and most importantly, the gain in a single torus such that they no longer have to be ganged together, and can withstand far more perturbation, so that they can be used for ship-drives. S:3 Pitch Drives give off a characteristic sound in operation which leads to their common name.

The operating principal of the portable Pitch Drive is simple. The smoke-ring torus is placed inside a long tube, with the axis aligned down the length of the tube. A large amount of reaction mass is directed through the center of the tube at high speed, decelerated along the way, then turned around and returned at much lower speeds around the outside of the tube. The torus has no reaction forces down the length of the tube, but does place hoop stresses equal to the thrust produced around the perimeter of the tube. The thrust produced on the outer tube is equal to the energy difference in the reaction mass moving in one direction compared to the other.

Since they are reactionless, Pitch Drives are much more fuel efficient at low speeds than any reaction drive. At high speeds, Pitch Drives are still more fuel efficient than Conversion ships, but if ramscoops are used, this does not matter nearly as much. As a result, Pitch Drives are mainly used for in-system drives, wormhole shuttles, and such while Conversion ships and Drive Sails continue to dominate interstellar transit. Pitch Drives used for interstellar trips can cruise at 0.84c and can mount shielding just as heavy as any Conversion ship.

Drive Sails

Also at S:3 a new type of interstellar drive comes into use, this one a much lower signature, lighter, and more subtle technology, the Drive Sail. Drive Sails use a combination of advanced techniques, all based upon advances in programmable matter and photoelectric effects. It is often forgotten that both electrons and photons are true elementary particles: Both are direct manifestations of strings, and they have near perfect energy conservation in their interactions. Drive Sails have three modes of operation, simple reflective lightsail, ramscoop with microwave photon drive, and selective photoelectric absorption/emission of ambient photons.

Drive sails are at their very most simple used as plain light sails, often with laser boosting or with mass streams shot by spacetime catapults. (Deepers make a good exchange providing mass streams and lasers in this fashion to customers in more of a hurry than they are. Drivesails are also usable as ramscoops, and have many miniaturized matter furnaces scattered across their surface. Collected matter is burned in the furnaces and the energy is used to power the rams and control the programmable matter. In this mode, the programmable matter is able to emit photons across the entire surface area of the drive sail. While the power level per square meter is low, since Drive Sails are often measured in light seconds the total power is very large. An even more advanced drive mechanism involves selective transmissivity/absorption/emissivity of ambient photons. Space is filled with photons, and the programmable matter of a Drive Sail can gain appreciable acceleration by absorbing photons on one side, moving the excited electrons from that absorption to the other side, and emitting the photons from that side. Using this technique, a Drive Sail can even gain motive force from the Cosmic Background Radiation, which is ubiquitous. Compared to Conversion ships and Pitch Drives, Drive Sails are considerably slower and more difficult to maneuver in tight quarters, but in wide open space can cruise at well over 0.95c, one of the fastest designs available if you have the patience for it.

S:4 Technologies

At Singularity level:4, a series of advances combine to enable the largest breakthrough to date, namely, the ability to manipulate space so that the very fabric of reality becomes an integral part of your space drive. The advances in question are the continued advancement and refinement in the creation of monopoles with useful, specialized properties, the advent of truly large scale intelligences with the related megascale engineering, and the exploitation of very, very large energy resources, so that direct spacetime manipulation becomes feasible. At S:4, the fruits of these breakthroughs are moderate sized pockets, or bubbles, of spacetime, which are larger on the "inside" than the "outside." Externally, such void bubbles are essentially invisible, as their apparent size is very small indeed. By manipulating the folded space they are made of, such void bubbles can be made to move in relation to the larger space we  live in. This action is completely reactionless, and even better for space travel, the mechanisms and matter inside the void bubble is not really IN our spacetime. As a result, all of the mass in the void bubbles is not subject to relativistic mass increase. Sadly, at S:4 the void bubbles created are relatively small, and worse, the bubbles cannot be undone non-destructively. This means that the bubbles are one-use only: Once the fuel within them is expended, they cannot be salvaged. Once an S:4 void bubble collapses, everything within is destroyed catastrophically.

At S:4, these devices are typically used as engines for more conventional vessels. These ships are then called "Displacement Ships" as their engines are displaced out of normal space. The use of void bubbles this way is commonly referred to as Displacement Drive. The bubble or bubbles are coupled magnetically to a cargo/crew pod, which is then equipped with a power source and active defenses similar to those of a high powered Conversion ship. Such ships can accelerate much harder than even Conversion ships, and do not have the deadly drive ray to worry about either, making them extremely handy and safe compared to earlier technologies.

S:4 Void bubbles are a tremendous advance, as they are much less tricky to use than a Pitch drive, far more energy economical than Conversion drives, and far more handy and useful than Drive Sails. The range limitations of an S:4 Void bubble are determined by the total mass that can be placed within the bubble and used as fuel, which is fixed when the bubble is made. In general, S:4 void bubble ships have a range of 1000 or more lightyears and a top speed limited only by the amount of fuel mass the ship captain is willing to expend on chasing lightspeed. In practice, few S:4 void bubble ships exceed 0.84c on a routine basis, in order to squeeze the longest possible lifespan out of the expensive drive bubbles. In theory, any bubble drive ship is able to reach at least 0.98c if it has the fuel mass.

At S:4 to S:6, the Conversion ship, Pitch Drive, and Drive Sail have steady, incremental improvements, but they have reached their mature forms at S:3 or before. Conversion ships, Pitch drives and Drive sails are still made in large numbers using S:4 technology, and as the mature drives, are considered the workhorses of deep space travel.

S:5 Technologies

Halo Drive

Halo Drive vessel

At Singularity level:5 Void Bubbles are still mostly "single use" technology, as they cannot be unmade without destroying most contents. Some extremely sturdy materials, such as high-density magmatter cases and certain high-energy magmatter vec clades may be durable enough to withstand the removal of an S:5 Void Bubble, but such reports may be apocryphal. The bubbles become much larger internally, and far more mass can be included within them as they are created. This has two very beneficial effects. First, the additional mass serves as a much larger fuel source, increasing the longevity of the drive bubbles. Second, the combination of the large mass and small size in our universe combine to give the bubbles a small but very steep gravity gradient.

Usually, S:5 bubble drive ships have many hundreds to several million drive bubbles around a fairly conventional deep space hull. Rather than coupling the bubbles to the hull solely by magnetics, the intense gravity gradient of the bubbles is also used to move the hull around. This has the large benefit of allowing the acceleration effects of the drive to be largely negated. This means that S:5 bubble drive ships can accelerate much, much harder than any previous technology. The hulls of these ships are equipped with the most advanced passive and active defenses available, and have the added defensive ability of the intense gravity fields of the  drive bubbles to call on. The use of void bubbles this way is popularly called Halo Drive, and ships using this method of locomotion are called Halo Ships. The reason for this is the blurry ring of distortion and blue glow of Cherenkov radiation the myriad of drive bubbles create around such vessels, which is a very impressive effect, to be sure.

S:5 bubble drive ships have effective ranges of at least 5000 light years, and top speeds limited only by the available matter inside the bubbles for fuel. Again, in practical usage such ships rarely exceed 0.84c on routine trips, to preserve fuel mass and extend the lifetime of the drive bubbles. For fast trips, top speeds of 0.99c are not unheard of, and the extremely advanced shielding allows very long cruises at such speeds if desired.

S:6 Technologies

At the level of the greatest Archailects, Singularity level:6, void bubbles reach their highest state of advancement. The three key breakthroughs are that the bubbles can now, for the first time, be taken down gracefully, so matter inside the void bubble can be retrieved without harm. Second, the total mass that can be placed into the bubbles is much greater than the capacity of S:5 bubbles, increasing the life-span of the bubble. Lastly, void bubbles can now be nested one inside another, and more importantly, wormhole mouths can be placed inside, allowing far easier access to the interior of the bubble without opening and thereby destroying it.

These three breakthroughs allow the spacetime ship to reach its ultimate expression, the Voidship. In essence, the external conventional hull is eliminated, as are the separate drive bubbles. Instead, the entire ship is inside a single giant bubble. Since such vessels, despite their enormous interior size and vast mass, are practically invisible, they are widely and romantically referred to as Void Ships, alluding to the fact that they occupy the Void, and not Space as modosophonts know it. Since the entire Void Ship is outside of our universe, meaning the vessel is no longer subject to relativistic effects, accelerations are astronomical, and range is extremely long. The maximum speed is high fractions of c; 0.999 at a minimum. Typical ranges are 5000+ lightyears.

Modosophont Ship Drive Stats (Typical Mass fraction 0.5 to .98)

 

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