Launch Loop
A launch loop is an active structure designed to loft payloads into low orbit without the need for expensive propellant.
A launch loop is a tubular monorail track that is held aloft by the motion of magnetic projectiles within it, whether discrete solid objects or a stream of liquid metal. These projectiles, known as armatures, are accelerated down the tube from the 'launch' end of the track by magnetic levitation coils, enter a hairpin at the 'landing' end of the loop, go back down a separate tube adjacent to the first, then enter a hairpin at the launch end to complete the loop. Passing over the circumference of a planet at high speeds induces a centripetal force upon the projectiles which, in turn, help keep the center portion of the track aloft. Long guy wires help to keep the loop suspended in the same tract over the surface.
SSTOs are the most common vehicles launched from, or landed upon, launch loops; despite their ability to take off and land independently, SSTOs launched from a launch loop still enjoy the benefits of fuel conservation. Vehicles launched from a launch loop magnetically couple with the armatures within the track and ride their momentum high up into the atmosphere, where a combination of the same centripetal force and the aerodynamic lift of the craft helps to fling the craft skywards. Later, a returning spacecraft can fly in tangent to the loop and couple with the armatures again, bleeding off its kinetic by donating it to the armatures and, thereby, slowing to a safe landing speed.
The most famous launch loop in Cobalt Protectorate space is the Grand Loop originating in Looptown on Planet Evermorn.
Utility
While a launch loop is expensive in terms of land use, construction materials, and initial startup power, it more than pays for itself over the course of its operational lifespan. It does this by making space launches extremely inexpensive per pound of mass - at least in comparison to other launch methods. A launch loop can also provide a secondary benefit in terms of energy storage for the settlements at the base stations, as, between launches, the motion of the armatures can be decellerated to regain some of the electrical energy used to speed them up in the first place.
Manufacturing
Launch loops are typically built through international (or, on Evermorn, inter-Clan) cooperation. Modern launch loops typically feature multiple tracks joined together in a single bundle to provide redundancy and allow for parts of the loop to be serviced even while the rest are still in operation. Launch loops are typically powered by fission or fusion power plants located near, or even within, the hairpin sections at either end. Large magnetohydrodynamic (MHD) generator/accelerator sections are embedded into the hairpins to get the armatures up to their initial speed; coils at regular intervals along the loop itself merely levitate and keep the armatures in motion.
Social Impact
Port towns typically spring up aroud the ends of a launch loop to service the needs of space travelers, launch loop technicians, and port officials. Like the seaports of old, these towns tend to be wealthy and debauched in equal measure.
Access & Availability
In Cobalt Protectorate space, launch loops are the preferred method of launching payloads from planets with long-established populations and industrial bases. For more rural locations, where the material conditions don't yet support the construction or operation of such megastructures, SSTO (Single Stage to Orbit) craft are preferred, as these only require landing strips and refuelling infrastructure.
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