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Sunday, October 9, 2011

Intrasystem Merchant Shipping

One of the things that knits together a scattered society is trade--the transfer of goods and people. Connecting the various population centers of the 94 Ceti System is the merchant shipping that moves both while plying the orbits between, and the auxiliary services that support it.

No matter what the propulsion system, all shipping moves by shaping orbits. As merchant shipping is a matter of moving cargoes between points in such a way that costs are less than value received at the other end, the least expensive method is to be preferred. This equation is made up of how much it costs to move the cargo and when its arrival is desired. There are three main propulsion systems presently in use: reaction, lightsail, and ballistic.

Reaction propelled ships use fusion powered elements that create a plasma when a reaction mass is introduced. The resulting plasma is directed aft through either a venturi or an orifice plate and produces forward movement per Newton's third law of motion. At the moment, there is great dispute among Power Engineers over the cost-effectiveness of the two designs. The argument boils down to the lesser efficiency of the less expensive orifice plate versus the higher efficiency of the more expensive venturi system. Whichever is used, the norm is for the ship to boost to speed to enter the most economical orbit to reach their destination. It is said that, among merchant captains, the 11th Commandment is “Reaction mass is money—thou shalt not waste.” The engine is then shut down and the ship coasts to a point at which it is then rotated 180 degrees. Its engine is restarted and brakes the ship until it arrives at its destination.

Lightsails, or sunjammers, rely on the primary's solar wind to move them outward and its gravity to draw them inward. This is an extremely inexpensive method of spaceflight, but comes at a cost; it is also extremely slow. Not only is the solar wind slow to accelerate the lightsail, but the originating port and the destination have to be in the proper alignment (this is why navigators aboard lightsails are tweaked as “astrologers”).

Ballistic carriers, known as “cannonballs,” are not accelerated by their reaction engines but, instead, are launched by mass drivers. Their reaction engines are not started until braking at the other end. The ship is accelerated by a system of electromagnets at the originating port and, thus, must be smaller than a reaction drive ship or a sunjammer. Because of this, cannonballs usually are used to transport small, high value cargoes. As another set of electromagnets is required at the destination to propel the ship on to its next port of call, cannonballs don't go off the beaten track.

Because most intrasystem ships are not built to make planetfall, but rather remain in planetary orbit, lighters are used to transport passengers and cargo between the surface and low orbit. Lighters also move reaction mass up to orbit for those ships requiring it where there is no orbital facilities. In the case of cannonballs, they must dock with orbital stations having the huge array of electromagnet rings they require for initial propulsion.

Shipping operates both under individual ownership and under the ownership of the “house lines.” These latter are typified by the Nakamura family's “Marus,” Steve Jackson's “Travellers,” the Gulf Consortium's “Universes,” and the Starr Lines' “Commerces.” A new entry in the field is the Dog Star Line with their four merchantmen, Star Husky, Star Beagle, Star Feist, and Star Boxer. At press time, Dog Star appears to be concentrating on operations between Ice Stations within the Oort Cloud. According to rumor, owner Silas Mariner, a former ice miner, got his start after winning a freighter, Star Fiest (nee, Rebargenette) and a tanker, Star Beagle (nee, Aquasynthesis) in a three-day poker game on Ice Station Zebra.

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