Friday, January 20, 2012

Space Infrastructure IV: Implication on Spacecraft Design

Space Infrastructure IV:  Implications on Spacecraft Design

          Wrapping this exhaustive look into the infrastructure it would take to run a multi-trillion dollar trade network in the Inner System is a brief look at the implications that all these tables have on the design of future space in our Ships of The Black Desert product line.

Not very likely...
SSTO is Exactly What it Says...and Nothing Else.
        The trade network supports the use of SSTO craft, propelled by our L-Drive engines, to lift cargo and fuel from Terra's surface to Low Earth Orbit.  This air-breathing propulsion system is not very practical when one wants boost to other locations.  By refueling in LEO, the spacecraft could make it to GEO and the tops of the space elevators, but this isn't practical;  The prop tanks on board only hold a quarter of the reaction mass that the L-Drive uses to boost from the surface, which means severely restricted delta-v.  besides, if you want to go to GEO, the cost of a trip up Jacob's Ladder or Yggdrasil is much cheaper than a spaceflight.  As far as going to Luna with a Terran SSTO forget about it.  The 4100 m/s needed to make a Trans-Lunar Injection exceeds the propellant capacity by fifteen tons.  This could be made up for with an auxiliary tank, but that would limit the cargo, the acceleration would have to be reduced in order to make the trip, which means the 1000-ton transports that arrive in LEO by the hundreds everyday are the better option.  Add to this that the interior of an SSTO will be so small that more cargo space would have to be sacrificed in order make enough living space for the two-day trip.

Combat Rockets and IPVs:  Realistic design = Different Approach.

     Most of you remember that spacecraft like the Heinlein and the Phoenix are designed to boost from the surface, travel as far as the Moon, and dock onto an IPV in such a way as to provide their crews with spin-gravity.  We've already seen how the SSTOs will not be boosting to the Moon, which means that they will not be boosting to the IPVs either.  This relegates designs like the two above to the role of orbital combat craft.  This is fine; even a cursory glance at the numbers show that everything good pretty much is in Terra's orbit anyway.  There will still be deep-space combat rockets, but their designs will be optimized for the environment, as a combat craft should be.  Military hardware, by necessity, is specialized to a specific mission, as the most expensive luxury is the second-best Space Force.

Now that I've Taken Away All Your Toys...
     ...I better have something cooler to give you in return, right?  After all, it's design restrictions like we're seeing above that usually make designers and authors soften their SF a little.  Most fans of the genre don't even mind; we want tramp steamers and spitfires in space, so that's what we get.  What I'd like to see, and I think a lot of you do too, is how to make something as exciting and dramatic as trading broadsides and buckling swashes while still keeping the setting plausible.  With that in mind let's see what the new model suggested by our space infrastructure can provide us in the way of entertainment.

     Before we get into it, there is one piece of space hardware crucial to the system That we haven't discussed yet:  The Cargo Container.  Just as this humble invention revolutionized freight transport in the present, going from ship to truck or being stacked on a wharf without the need for a warehouse, the space-worthy equivalent will be used extensively in The Black Desert.  The containers will by tapered cylinders with a ten meter diameter and 9.5 meter length.  These enclose 750 cubic meters; that's 250 tons in traditional freight calculation.  These tuna cans are the backbone upon which the entire system will be built. 

Terra to Mars: An Example
     One of the background elements of The Black Desert is that there is a lot of travel from Earth to the blue shores of Mars by artists, writers, and other members of the culture renaissance of the post-war period.  How would they get there? 
       First, there would either be a ride up a handy Space Elevator or on one of the SSTOs.  While our fictitious traveler could take a trip to one of the many, many orbital hotels or factories, we're just looking at an "express" trip to Mars, so we'll skip that.  The trip (assuming our traveler's mass is 100kg including baggage) will cost close to $2,000, or L$U1,000, so focusing on the final destination is important.  From one of the big commercial hubs in LEO, our traveler must transfer to one of the Intra-Orbital transports that will be boosting to the La Grange points or Luna.  This trip takes nearly two days and costs another $1,425; the original 100kg allotment plus consumable for the ride.  From the transfer hub, our traveler will board an IPV bound for the Red Planet, fly for ten weeks ($5,625) arrive at Deimos and board a Martian SSTO ($500) and then arrive at Hopkins or Zubrin with their gear.  Total travel time: 73 days, total cost, a minimum of $9,550.  That's just the traveler, with maybe 10 kilos of stuff.

         Looks pretty bleak.

         There is hope for our traveler, especially if they happen to be a player character in an RPG.  First, these are standard rates; discounts, back door deals with contacts, standby seating and other bits of razzle-dazzle can lower the cost by a good bit.  If the PCs plan on actually working on Mars, instead of just sightseeing, they can either float a loan against their future wages or even have the transport cost payed for, if their employer is well-heeled or connected.  Then there is also the classic trope of working passage; some or all of the PCs may join the crew of an I-OT or IPV in order to pay for their passage to Mars.  In short, trying to get to another planet, which is a big part of what The Black Desert is all about, offers numerous adventure ideas all by itself. 

No Millennium Falcon or Serenity?  Maybe...

         But what about that most tried and true of SF Tropes:  The Tamp-Steamer-In-Space?  This model of the Black Desert doesn't seem to offer our PC parties any chance to own their ship and ply the trade between Terra and Mars with just their own resources.  This kind of limitation, so counter-intuitive when you look at conventional SF, is the kind of thing that make designing a Hard SF game so challenging.  What ever shall we do?

        Like the venerable Traveller RPG, the idea of PCs in The Black Desert owning their own spaceship is unlikely for all but the most economical and diminutive of craft.  Assuming an optimistic $250,000/ton cost of construction, an average SSTO would cost 37 million new and probably not depreciate more than 25% over it's lifetime.  Think about it;  Challenger and Columbia showed what happen to old orbiter if they are not perfectly maintained.  So owning you own spacecraft free and clear is not likely unless you're rich or an heir or something.

       There is one option:  Spacecraft like this month's CASSTOR launch vehicle can be owned by normal folk, and there are a bunch of 'em.  If spacecraft like this are used to get cargo into space then serve as the command module of a I-OT, they could also conceivably be used as a carried craft on one of the larger IPVs.  These rockets could haul a cargo into orbit, hook up to a transport,dock with an IPV for the trip to Mars, and then be used to drop cargo onto the surface.  This model is a silly way to design a ship except for the possibilities offered by modular hulls, where the command section can dock to, then pilot, multiple spacecraft.  If we assume this would happen, an adventuring party could travel from Terra's surface to Mars' on their own rocket.

      It's going to take some work; fortunately, designing spacecraft is what I do.


  1. The approach I took to justifying tramp space transports is that the only real barrier to owning your own spaceship is the sheer cost involved in purchasing, maintaining and supplying it. For example, when Jon and Tallen bought the Peregrine, they pooled their life savings, took out a mountain of high-interest loans and after all that they could only afford an aging and heavily retrofitted light freighter that was described as a "unique fixer-upper opportunity" in the classified ad (turns out that some of the nothing parts the manufacturer put in to make the ship come in for overhauls more often broke down. After Tallen fixed the ship's powerplant, not only did he manage to streamline the operation process, but also managed to lighten the ship by removing several tons of useless parts).

    Frequently, their interplanetary jobs tend to pay in the millions (2011 USD), but almost all of that goes to refilling propellant tanks, replenishing food, water and air supplies and replacing failing parts. This tends to leave them living like working poor, especially considering all the ancillary expenses (docking/landing fees, hotel stays (can't use the centrifuge while landed), inspection fees and fines, insurance, etc.). Of course, since most of the well-paying jobs are already taken up by big corporate franchises and the rest don't pay very well (considering operating expenses, a million bucks won't support three adults on a spaceship for a month), so most independent space crews tend to take a few illegal jobs here and there in order to make ends meet.

    Oh, and here are the Kestrel pics I promised:

  2. J. Lovell, huh? I thought he flew Banshees and space capsules... ;)

  3. Wrong Lovell, but probably a distant relative or a great-great-great-great-great grandchild or something.


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