Distances and travel

Warp propulsion allows humanity to move regularly between systems separated by tens of light years, but it has not eliminated the distances that separate them. Crossing interstellar space still takes weeks, months or, on the most distant routes, years of travel; a colony’s position relative to the main industrial centres therefore remains one of the decisive factors in its economic importance, its autonomy and its living conditions.

Alcubierre Drive

The fundamental unit of interstellar mobility is the Alcubierre Drive, a designation that has remained in use for the various generations of warp drives developed from the first experimental systems onwards. Although they have progressively moved away from the implementation imagined in the twentieth century, these technologies continue to rest on the same general principle: using Voidmass to produce a controlled deformation of space-time, allowing a ship to cover a distance at an effective speed greater than that of light without locally exceeding it. The deformation does not in fact act on the ship, but on the region of space that contains it (the so-called warp bubble), which translates with respect to the surrounding space, carrying its contents with it.

The performance of an Alcubierre Drive depends on the quantity of Voidmass the system is able to keep under control, on the power available, on the mass of the ship and on the capacity of the containment systems. Increasing speed entails rising energy costs and stresses, making it uneconomical to keep the drive continuously at full power; for this reason a ship’s maximum speed is normally distinguished from its cruising speed, that is, the speed it can sustain for long periods without excessive consumption, wear and risk.

The way the drive works also determines the way ships are flown. Heading and speed are set before departure: at the moment of the Phase Shift, that is, of entry into the warp regime, the system establishes the geometry calculated for the trajectory; once stabilized, this can no longer be reconfigured, since no command issued from inside the warp bubble can reach the forward front of the deformation; during the crossing the vessel is therefore obliged to follow the trajectory established. The ship nevertheless retains the possibility of interrupting transit by activating a dedicated instrument, called the Quencher, to cause the controlled collapse (quench) of the field that sustains the warp bubble. Every course correction or change of speed therefore requires returning to normal space by activating the Quencher, recalculating the trajectory and performing a new Phase Shift, at the expense of the charge in the Voidmass matrices.

A fundamental peculiarity of this system is that a vehicle does not necessarily have to possess an Alcubierre Drive in order to enter warp: the Phase Shift can also be generated by an external propulsion installation, capable of calculating the trajectory and creating around the vessel the geometry required for transit. Once stabilized, the bubble can continue on its own for as long as the field that sustains it remains active. The Alcubierre Drive becomes indispensable when the vehicle has to perform further Phase Shifts in the course of the same journey: after each quench, only a vessel equipped with the systems needed to calculate and generate a new warp bubble can resume transit on its own. A vehicle without a Drive can therefore be launched into warp, but once it has come out it cannot re-enter.

Warp speed

In the course of the twenty-first century the performance of Alcubierre Drives has increased rapidly. The first models, used mainly within the Solar System, reached effective speeds of a few multiples of c. The generations developed from 2060 onwards consistently exceeded 20-30 c, making the first interstellar expeditions practicable; in the following decade normal operating speeds reached 40-60 c.

At present, most commercial and industrial ships maintain cruising speeds of between 50 and 90 c. Much of the fleet in fact carries drives of earlier generations, less fast and less efficient but still fully operational: latest-generation units are extremely expensive and cannot be installed on just any hull. The most modern units can reach 100 c, while higher speeds, up to the 120-150 c that represent the current technological limit, are generally reserved for couriers, military units, emergency missions and other operations in which cost is of secondary importance.

The figures indicate the effective speed reached during the stable warp phase and therefore do not correspond to the overall duration of the journey.

These times represent ideal conditions. An actual crossing can take appreciably longer because of the operations for entering and leaving warp, the deviations required along the route, gravitational conditions and any technical stops.

Interstellar navigation

An Alcubierre Drive cannot be used with the same efficiency in every region of space: the presence of strong gravitational fields interferes with the formation and stability of the geometry produced by the drive. Departing ships must therefore move far enough away from the main gravitational fields (stars, planets, etc.) before they can establish a stable warp; likewise, an arriving ship must leave warp at a safe distance from the destination system and then complete its approach by means of sublight thrusters.

This limitation affects interstellar navigation in several ways. First of all, the geometrically shortest trajectory between two systems does not necessarily coincide with the safest or the most efficient, since the presence of celestial bodies, gravitational anomalies and interdicted or dangerous areas (cf. active Thanant Relics) may make it necessary to alter course or to interrupt transit with a quench, recalculate the trajectory and perform a new Phase Shift at a lower speed. The need to guarantee reliable connections also explains the development of a vast network of infrastructure dedicated to the management of interstellar traffic: depots, refuelling stations, shipyards and the so-called fishing nets, containment structures based on Voidmass matrices, deployed at the margins of systems and in the vicinity of stations, capable of breaking the warp of incoming vectors and holding them until recovery. Originally conceived for catching postal PODs, the nets also serve as an emergency haven: a ship with failed drives can head for one of them and let the structure provide it with a controlled exit from warp.

Gravitational margin and sublight navigation

The distance at which a ship can establish or break warp depends on the intensity of the gravitational field and on the speed planned for the transit. Around every star a gravitational margin can be identified, beyond which the field is weak enough to permit a stable geometry at the speeds used in interstellar crossings. In commonly inhabited systems this margin lies a few astronomical units from the star, with values varying according to its mass: the main postal stations are normally sited close to this band.

Once the quench has been performed, the approach or departure continues by means of the sublight thrusters (PSL), the non-FTL apparatus that every ship possesses alongside the Drive and that in common speech are called oars. PSL can develop peak accelerations of more than 1 g, needed for lift-off and for leaving the atmosphere, while on ordinary crossings they generally operate between 0.3 and 0.7 g. The stretch between the gravitational margin and the main inhabited planet normally takes three to five days, and corresponds to the part of the crossing that crews placed in suspended animation spend awake.

Warp can nevertheless also be used within a system: a Phase Shift performed at reduced speed requires less restrictive gravitational conditions and therefore makes it possible to connect planets, satellites and the outer regions of the same system quickly. The manoeuvre entails an additional consumption of charge, but reduces to a few days journeys that on PSL alone might take weeks. In the vicinity of the larger planets a stretch of conventional navigation is still required, generally of the order of a day.

These distances are not absolute limits: a ship can perform several consecutive Phase Shifts, progressively reducing its warp speed and drawing closer to its destination before the final quench. Each change, however, requires a quench, a recalculation of the route, a Phase Shift and an additional consumption of charge. These “micro-adjustments” are used above all by couriers, military units, emergency transports and in all situations in which the time saved justifies the greater cost.

In the case of destinations that generate a negligible gravitational field (postal stations, spaceports, space bases, etc.), a ship could in theory break warp a short distance from arrival; in common navigational practice this does not happen, because of a convention known as the 24-Hour Rule, according to which every interstellar ship is required to perform its quench with at least one day of conventional navigation remaining before arrival: this practice, almost universally accepted although formally absent from the Space Navigation Code, gives the local authorities the time needed to identify the vessel, check its flight plan and authorize its entry. The distance corresponding to “24 hours” obviously depends on the ship’s approach profile, and is normally between four and thirteen million kilometres.

Certified routes

FTL navigation is not normally carried out along improvised trajectories, but through a network of certified routes, surveyed in advance and periodically updated on the basis of gravitational conditions and known hazards.

A certified route is a succession of trajectories and procedures considered safe enough to be used regularly to connect a given point A to a given point B. Producing one requires large quantities of astronomical data, gravitational simulations and continuous updates concerning the condition of the leg, the traffic and the presence of new interdicted or dangerous areas. Routes are therefore distributed in the form of licensed software packages, updated whenever new information reaches the system, which typically happens when the ship docks at an authorized space station or at one of the support facilities along the leg.

The main advantage of certified routes is that they allow ships to maintain high speeds with a relatively contained margin of risk, guaranteeing a higher level of safety than manual navigation. For this reason, control of the routes is one of the central elements of interstellar politics: Hegemonies and MC invest vast resources in cartography, in the maintenance of support infrastructure and in the protection of the main commercial links. A colony situated along an important route can acquire an economic value far greater than that determined by its natural resources alone, while an apparently rich system can remain marginal if it is difficult to reach or lacks safe connections.

Although it is technically possible to copy one, a certified route does not consist of the trajectory alone: it comprises ephemerides, warp parameters, corrections accumulated from previous transits and updated information on the condition of the entry and re-emergence points. A copy no longer fed by these updates therefore progressively loses reliability and, on less frequented or less well known legs, can become unusable or dangerous. Some stations are also equipped with systems capable of verifying the authenticity of navigation licences and detecting the use of copied or altered routes; in such cases the penalties laid down by the Space Navigation Code and by the legislation of the competent Hegemony are applied, and for the most serious violations these can extend to confiscation of the ship.

Long-distance travel

A crossing of a few tens of light years can keep a ship under way for many months: crew, food, water, spare parts and life support systems would account for a considerable part of the mass carried if everyone on board remained active for the whole duration of the mission. For this reason the longest legs are normally covered using suspended animation: once departure operations are complete and warp has been established, most or all of the crew are placed in the capsules, while the onboard AEGIS takes over control of navigation, life support, Voidmass containment and the monitoring of the passengers.

The AEGIS (Autonomous Executive Guidance & Intelligence System) is the class of AGI certified for the autonomous command of starships and, during the crossing, holds full operational authority: it can order a quench, recalculate the trajectory and perform a new Phase Shift, or direct the ship towards a fishing net in an emergency. The crew is normally revived before arrival, when operations requiring a human presence have to be carried out, or during the voyage should the AEGIS detect an anomaly it cannot handle on its own. It is always possible, in any case, to schedule one or more intermediate revivals and temporarily resume direct control of the ship, handling its navigation and main onboard systems manually.

Ships without an AEGIS can still make interstellar crossings, but they require a constant human presence during the voyage. In such cases the crew is normally divided into watches, so that at least part of the personnel remains conscious at all times to monitor navigation, Voidmass containment, the onboard systems and the people in suspended animation. Less sophisticated automatic systems can handle routine operations and report any anomalies, but they lack the autonomy needed to take complex decisions without oversight. For this reason ships not fitted with an AEGIS require larger crews, consume greater quantities of resources on long crossings and are generally less economical on the more distant interstellar routes.

Entering and leaving suspended animation

The two operations take very different lengths of time. Entry takes two to four hours and is a schedulable procedure: the subject is prepared, the descent is started and monitoring is handed over to the AEGIS. Exit, on the other hand, takes twelve to twenty-four hours, since the recovery of circulatory, thermal and neurological function follows the timing of the organism and not that of the operator.

From this asymmetry follows the most important operational constraint of life on board: personnel in suspension do not constitute an available reserve. Faced with an emergency in mid-crossing, the crew that can actually be employed is the one already awake, and it will remain so for at least half a day. Ships travelling with a reduced watch therefore size that watch on the assumption that it will have to cope on its own.

The duration of revival also explains why the sublight legs habitually coincide with the crews’ return to consciousness: twelve to twenty-four hours correspond exactly to the conventional distance for leaving warp at an orbital station. A wide exit allows the crew to present themselves at docking at full efficiency; a close exit saves the ship time and brings it alongside with part of the personnel still in the process of waking, and is one of the reasons why prudent commanders prefer the margin.

Communications

The most important limitation of interstellar travel concerns not the transport of matter, but that of information: at present there is no known technology capable of transmitting a signal through space at speeds greater than that of light. This means that no radio, laser or other known form of communication can be used effectively to maintain timely contact between distant systems.

To overcome this limitation, information is physically carried by ships. Commercial convoys, military units and courier ships continuously carry large quantities of data between inhabited systems. The information is downloaded on their arrival, integrated into the local networks and subsequently forwarded to other destinations. On the main routes this system produces a relatively regular flow of updates; in peripheral colonies, on the other hand, weeks or months can pass between the arrival of one courier and the next.

The inevitable consequence of this mechanism is that systems distant from one another can live at the same time in very different states of information: a decision taken on Earth can take months to reach a colony; by the time the reply comes back to the Solar System, the situation that had prompted that decision may have changed more than a year earlier. Political crises, industrial accidents and local conflicts may therefore begin and end before the central authorities receive news of them. The same limitation also affects urgent communications, including distress calls.

This condition has inevitably encouraged the progressive growth of the colonies’ administrative autonomy, the power of the MC and the spread of local authorities able to take decisions without waiting for instructions from their respective Hegemonies.

Postal services

In an attempt to overcome this limitation, a dedicated infrastructure has developed over recent decades, composed of a series of postal stations located along the main routes, typically close to the gravitational margins of inhabited systems: these are physical relay nodes at which ships and certified couriers can deliver and collect data, packets and light cargo, reaching them on sublight thrusters without leaving their route. It is possible to collect one’s own mail, to send items to other stations and, if the ship is a certified courier, to carry all or part of the messages and/or parcels with a compatible destination to the next station on its route.

The status of certified courier can also be obtained for a ship not originally intended for postal transport, provided that a series of third-party systems prescribed for the role are installed and kept active. These devices guarantee the correct acceptance of the mail, the encryption and integrity of the data, the traceability of packets, the automatic recording of transfers and compliance with the chain of custody up to delivery at the next station. The certification is renewed periodically and can be suspended or revoked in the event of tampering, violations or failure to comply with the prescribed protocols.

Alongside the system of certified couriers there is a second transport mechanism, used when normal forwarding times are not sufficient or when the destination is not served frequently enough by the commercial routes. Its characteristic vector is the Personal Object Delivery (POD).

POD

The Personal Object Delivery (POD) is a small automated capsule designed to be launched directly towards a predetermined destination without waiting for a courier to pass. Unlike ordinary mail, which is transferred progressively from one ship to another along the network of stations, a POD follows a trajectory programmed specifically for the individual launch. A small single-charge Voidmass matrix allows the capsule to maintain warp for the entire crossing, while arrival normally takes place through one of the fishing nets present in the destination system, which break the warp and hold the vector until recovery. This makes it possible to send data, documents, small loads or urgent material directly, even when no direct courier is available or when waiting for the next passage would take too long.

The main advantage of the POD is that it can be used outside the conventional certified routes: its trajectory is calculated specifically on the basis of the available data and the vector is, in the jargon of those who use it, “fired” straight at the destination point. Dispatch by POD, although considered less secure than the use of a certified courier since it lacks the chain of custody and protection guaranteed by the postal service, has proved in recent years a particularly effective instrument. The “fire-and-forget”, single-use and one-way nature of the system nevertheless restricts its use to urgent communications, distress calls, military operations and links with peripheral settlements served irregularly or lying outside the conventional postal network.

The use of the POD is not limited to carrying mail: the device can be configured to hold a person in suspended animation, replacing the cargo bay with a capsule and its associated life support systems. In this configuration the POD also serves as an escape capsule, allowing a ship in difficulty to “fire” one or more crew members towards a station, a colony or another predetermined recovery point.

This “dual function” has inevitably ended up creating one of the most difficult dilemmas of life on board: since every ship can carry only a limited number of PODs, using one to send any message at all, even a distress call, means giving up a possible means of escape.

Whatever the mode of use, it is important to bear in mind that a POD is not a starship, but an extremely simple vector that can only be programmed, launched and left to its own trajectory; once away it cannot change destination, nor interrupt or re-establish transit on its own: lacking both an Alcubierre Drive and a Quencher, it can do nothing but carry on. The initial Phase Shift is generated by the launch infrastructure, while the Voidmass matrix installed on board merely keeps active the field that sustains the bubble, exhausting its charge on the way to the destination.

This characteristic also explains why not all PODs manage to reach their intended destination: errors in navigation data, unforeseen gravitational variations or malfunctions can cause a capsule to miss the receiving net; in such cases the vector carries on until its charge is exhausted and thereafter remains adrift in space. A POD’s transponder nevertheless goes on transmitting its position into the surrounding portion of space for several years, which allows some of those lost to be recovered even long after launch, while others are never found at all. For all these reasons, in the jargon of the crews the POD has accumulated numerous sinister nicknames over time: bullet, coffin, niche, one-way round, etc.

Finally, the POD should not be confused with the Cutter, the auxiliary shuttle with which the larger ships are equipped. The two craft share their mode of departure, since both can be launched into warp by the mother ship, but the POD is a single-use vector that once away can do nothing but carry on, whereas the Cutter is pilotable and has a Quencher.

Clipper (CLPR or CLP)

The highest level of the postal service is represented by the Certified Light Priority Runner (CLPR or CLP), conventionally known as the Clipper: fast ships using light hulls and minimal crews, built around an Alcubierre Drive oversized relative to their mass. Clippers run the routes at speeds closed to commercial ships, carrying data, critical personnel, orders and emergency cargo. Employed by the MC, by the authorities and by anyone who can afford them, Clippers are today the fastest and most reliable means by which information can cross space.

The acronym and the name have been chosen in homage to the nineteenth-century “clippers”, the fastest sailing ships of the age of sail: built with speed favoured over cargo capacity, those vessels ran from China to England to deliver the tea of the first harvest, which on the market was worth many times that of the later cargoes; the companies went so far as to organize genuine ocean races, with records celebrated in the press and bets placed on the dates of arrival.

Almost three centuries later, the economic logic of the CLP has remained exactly the same: to guarantee the maximum possible speed, at any cost. Even the tradition of racing has survived the passage from sail to warp: transit times on the main legs are recorded and publicly compared, route records are contested between companies and crews, and there is a flourishing market in more or less clandestine betting on the dates of arrival.