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Interstellar Catapults Interstellar catapult at
Duktig of the Chronos
Cluster,
delivering a train of diamondoid unfolders to Ikaros for the
terraforming of Ikaros III. The cargo is accelerated using local
spacetime manipulation, producing an intense gravitational gradient
that accelerates it with minimal force. The packages will be received
after 164 years at Duktig, with a maximal deviation of 10 meters.
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Launching objects using electromagnetic catapults is nearly as old as space travel. On airless worlds it is one of the most efficient ways of cargo launch. It can also be used for transports in interplanetary or interstellar space. Sending objects by catapult has the advantage of not requiring any expensive drives or ships to house the cargo; the catapult and receiver station are the only major investments and can (at least in theory) gain economy of scale.
While electromagnetic or mechanical catapult-like systems have been developed for in-system travel, such as the Federation Fast Forward System (F3S) of the Solar System or the Djed rotovator networks, the practice remains of limited use because the accelerations or jerks involved tend to damage bioids and cargo. Also, the competitiveness and efficiency of in-system drives have often driven down profit margins so much that catapults become uneconomical. Interstellar catapults remained a theoretical possibility for a long time, but was eventually developed into an economical viable system, mainly in systems without stargates.
While drive technology at first concentrated on devising fields that could propel starships efficiently, there were serious interest in other applications. Sirius Dynamics and New Mars Applied Quantum developed several "launching fields" that could accelerate objects to high velocities. At first suggested both for megascale planetary launchers, weapons and even thrusters, they proved too energy consuming, heavy and dependent on high vacuum to work well with any of the applications.
During the expansion of the Mutual Progress Alliance in the 5000's, many systems lacked stargate links but needed to exchange material objects (especially for the enormous terraforming programs of the Kusilaire administration of the Ophiuichi Pyramid). Much work on applying field technology to interstellar catapults was done, and the company/clade Emek could in 5284 demonstrate a working prototype, sending streams of multi million ton masses over a distance of one lightyear at the MPA engineering testing range at Antares. Over the centuries, the system was deployed and refined into the current streamlined designs.
The basic catapult is a linear accelerator containing exotic matter tori and a meshwork of controlling picotech systems. Protective foil, energy sources and direction adjustment systems surround the accelerator proper. A typical length is 20 kilometers, with a diameter of 100 meters. The object to be launched is introduced at one end, and a peristaltic drive field is applied creating a massive acceleration. When the object leaves the accelerator it may reach velocities of 0.1-0.5c. Usually a stream or train of cargo containers are launched together, and a launch report is beamed to the destination using laser link.
During travel, the cargo needs to be protected from collisions with interstellar dust and cosmic radiation (if necessary). This is often done by first launching a somewhat broader "sacrificial" cargo in front of the cargo train, or by using standardised armored relativistic protection containers (often called relpros; the truncated octahedron or cubical relpros are extremely common in some systems, being used for a variety of purposes such as housing, radiation proofing or even outfitted with thrusters and used as extremely minimal spaceships).
In the receiving system the train of cargo is slowed by a recipient deaccelerator. This requires extreme precision - an error of 10-14 degrees during launch will lead to a 100 meter deviation at one lightyear. Fortunately detailed information on the launch and far-system astrometry, as well as the mandated relpro position beacons, enables the recipient to plan the catch months or years in advance. Usually recipient systems either use a very long and wide "funnel" deaccelerator to stop the cargo. In some more primitive systems the cargo containers slow themselves using magnetic or solar sails. Lost cargo is of course highly dangerous, so reception zones are always high above the local ecliptic and receiving systems are only manned by automation or often upbacked aioids.
The major problem with field catapult launches is tidal forces. A very long object would have a front end move at a higher velocity than the back end during the acceleration phase, experiencing a potentially devastating tension. This is the reason most cargo containers are small (usually less than five meters) and sent in streams. It should be noted that a well tuned catapult does not produce any accelerations on the contents of the cargo. The cargo remains in free fall in the local gravitic gradient, only experiencing tidal forces and possibly higher order momenta. While passenger traffic is in principle possible, it usually requires very large accelerators to produce a sufficiently non-tidal field to allow a container containing bioids and their life support to be launched.
The field catapults are today in wide use in the outer volumes, as a cheap alternative to massive starship traffic or stargates. They work well in archipelagos and clusters of systems, with fixed relative positions and regular shipments. While the construction of a field catapult requires picotech systems and high-end AI, the operation is much simpler and can be handled by the embedded AIs and maintenance crew.
During the Version War and afterwards some catapults have been converted into relativistic launch weapons. They are not cost effective for small payloads, hard to shift aim with and very vulnerable due to their size and energy consumption, but very suitable for planetary bombardments of antimatter or relativistic projectiles. The combination of a field catapult and a small aiming stargate has been used as a very expensive but more flexible system strike weapon by the Solar Dominion and the MPA.
