Space Infrastructure III: IPVs

In The Black Desert, This is the Mars Express

 Space Infrastructure III: IPVs         

         In the last two posts, we pretty much nailed down how many tons of cargo a developed trade network in the Solar System would need to move and how many small rockets would be needed to unload the billions of kilograms of freight that asteroid cyclers would be bringing on their biannual trips between Mars and Terra.  Today, we'll be looking at the Interplanetary vehicles that move people across the void and their military equivalents.

        One thing about IPVs in the context of The Black Desert that's worth remembering is that they didn't appear on the scene until the Great War broke out in 2152.  That means that they've only been a part of the trade culture for half a century and only about thirty years as far as civilian transport goes.  Because of their size (tiny, compared to an asteroid) and expense, they are only good for really high value, low mass cargo and passenger service, where speed means less consumables.  Because of this, the IPV service accounts for only a fraction of the total tonnage that move between Earth and Mars annually. 

        That being said, the Trojan asteroid nodes that follow and precede the two planets in their orbits must be supplied by the IPVs, because the cyclers do not come close enough often enough to keep the Nav Laser installations supplied with food, to say nothing of new equipment or personnel.  All of these factors put together lead us to our next Table, seen here below:

Table 7: IPV Cargo and Propellant Requirements by Planet

Surface to Orbit Transport Requirements	Total (all IPVs x4)	Terra/ Luna	Hektor	Paris	Mars	Agamem- non	Achilles	Aldrin
Propellant (H2O)	1,024,000	512,000	3,000	3,000	1,024,000	3,000	3,000	1,000
Tanker trips	-	2,045	8	8	852	8	8	3
No. Tankers	-	2 (10)	2	2	212	2	2	1
Cargo	1,022,520	511,260	2,679	3,258	12,066	3,750	2,649	2,433
Transport trips	-	2,045	11	13	48	15	11	10
No. Transports	-	3 (15)	3	4	12	4	3	3
Indepen-dent	-	-	0	0	9	1	1	0

         The total column (all IPVs x 4) is there because the IPVs can make a maximum of four trips between Mars and Terra a year, on average.  Some of the Trojan nodes take nearly six months to reach, depending on where you start from, while Mars to Terra at conjunction take only a month and a half; it evens out.  All IPVs pretty much hit Terra and Mars in their annual schedule, as these are the main hubs of interplanetary transport.  You'll see that the number of rockets and tankers needed to haul the IPVs cargo from orbit to the surface is so low that it barely counts as a rounding error compared to the asteroid freight that moves every day, so the idea of a separate service just for IPVs is a little far-fetched.

       The above table might make more sense if we nailed down just how many classes of IPVs there are, what they can haul, and how much gas they guzzle on the trip.  Those figures are found below:

Table 8: Interplanetary Vehicles

IPV Statistics	Heavy (Carrier)	Medium (Cruiser)	Light (Escort)
Dry Mass (Tonnes)	14000	8000	5000
Propellant	6000	3000	1000
Cargo	6000	3000	1000
Crew	50	40	20
Passengers (typ.)	55	40	5

       These numbers are base on the designed I've showed off on the site before, ans are admittedly pretty arbitrary.  There just isn't any hard data at all as to how a magnetopheric plasma sail would perform in real life, and the speculations vary wildly depending on who you ask and how they feel about solar sails.  The crew requirements are based on my Mission Control model, the cargo and propellant is practically made up, and the passengers follows my logic for what military spacecraft would need, which is what pretty much all IPVs currently in service started out as.    While the numbers may be based on a scarcity of hard data, they do let us figure how many spacecraft we need to have in service:

Table 9: Interplanetary Vehicles by Type and Origin

IPVs	HTL (Carriers)	MTV (Missile Craft)	LTV (Escorts)
Tonnage	511,260	340,840	170,420
Capacity per craft	6,000	3,000	1,000
Flights Annually	85	114	170
Number of craft (Merchant)	21	29	43
UACS	1	2	6
Brazil	5	8	14
Siberia	3	3	13
EAP	-	-	10
Mars	10	15	-
NuRom	1	1	5
Number of craft (Military)	5	7	10
UACS	1	1	6
Brazil	3	3	2
Siberia	1	2	1
EAP	-	1	1
Mars	4	8	-

         So, here we are; a breakdown of how many IPVs there are in The Black Desert, who owns them, and how many haul deadly Kinetic Killers as opposed to cargo.  The number of military vehicles is based on Rick Robinson's assumption that the amount of cargo craft tonnage/5 will give us a good round figure for the size of the Navy/Space Force needed to protect the trade routs in question.  The divisions between the different nations comes from my future history; we know that Mars has more IPVs than any body, Brazil has more than the rest of Terra, and UACS created the escort class originally and would therefore have more of them.  The rest of the data are just fiddly math, but serve to make future scenarios more precise.  I can now calculate the probability of a military IPV from a specific polity being in orbit around a specific planet at any given point.  I can also figure how long PCs will have to wait at L5 before they can get a lift to the Aldrin cycler node.  In short, I can really provide some plausible, hard data to my fantastical setting, which will boost the realism and make the future a more fun place to play.

         Besides, I had a lot of fun with this.

         Tomorrow, I'll be wrapping up this series with a look at the implications this hard data has on my previous assumptions, and on how all of this will effect future spacecraft designs and my other products.  See you then!