[Space, Spaceships] Mars Semi-Cycler?

[DaltonS]

I've been studying the idea of the Mars Cycler, and I have to say that it's a lot more complicated that it looks at first glance. Part of it is the orbital mechanics and the rest of it is the logistics. While the cycler itself would use much less ∆V that other Mars mission profiles, it's more than made up for by the "taxi" craft that shuttle passengers to and from the cycler during flybys . (Since the "taxis" would be much smaller than cycler, the absolute amount of propellant expended would be less.) Still, the idea of traveling on an interplanetary "Flying Dutchman" is a bit daunting.

I've come to prefer the idea of the free-return semi-cycler. Instead of using an orbit based on the Earth-Mars synodic period (780 days), the ship would use a free-return orbit of exactly 2 years (730.5 days) which would require two 3.16 mps burns to leave and re-enter Earth orbit, where it stay for 49.5 days being refueled and refurbished for the next mission. According to my calculations, the taxis would require a ∆V of 5.68 mps between the cycler and Mars orbit each way because the transfer orbit crosses that of Mars at an angle of 21.6 degrees. Below is my example of a TL9 cycler.

Perdue-Class Medium Interplanetary Transport

PILOTING/TL9 (LOW-PERFORMANCE SPACECRAFT)

TL  Spacecraft  dST/dHP  Hnd/SR  HT       Move        LWt.     Load    SM      Occ      dDR  Range    Cost   
 9    Perdue       70     -4/5   13  0.0002G/10 mps  1,000  396.4 [1]  +8  10ASV [2,3]   10    —    $18.74M

Length: 50 yd. (150 ft.) Crush Depth: 30.3 Atmospheres (1,000 ft.)
Power Points: +1 / -1
Space Performance: sAccel: 0.0002Gs/10 mps


SHIP SYSTEMS

 FRONT  
[1]     Armor - Metallic Laminate
          dDR 10
[2-3]   Cargo Hold
          100 Tons / SM+3 Bay Doors
[4-6]   Hangar Bay
          Cap.: 90 Tons / SM+5 / Launch: 50 Tons/min
[Core]  Control Room
          Computer: C6 / Comm/Sensor: 6 / 4 Stations

CENTER  
[1]     Armor - Metallic Laminate
          dDR 10
[2]     External Clamp
          1,000 Tons
[3-6]   Vehicle Dock
          200 Ton Capacity / SM+0 [4]
[Core]  Habitat
          6 Cabins

 REAR   
[1]     Armor - Metallic Laminate
          dDR 10
[2†]    Power Plant - Fission Reactor
          1 Power Point / 50 yr Fuel [5]
[3!]    Reaction Engine - VASIMR Electric Rocket
          0.0002Gs / 10 mps / 0.002Gs / 0.5 mps / 95 days Fuel [6,7]
[4]     Engine Room
          1 Workspace
[5]     Fuel Tank
          50 Tons of Hydrogen
[6]     Habitat
          6 Cabins

User Notes: The modular Vehicle Docks can hold two SM+6 auxiliary craft, usually atmospheric craft such as Midnight-Sun or Condor class shuttles used as orbital taxis. (Modularity allows the customized docks to be swapped in and out as required.)
Design Switches, Features, & Notes: 4 Airlocks (Capacity: 4 people each), Refueling Cost: $100,000, Food Supplies: $15,000
[1] Load includes: 1.4*tons of Crew & Passengers, 15*tons of Standard Food (7,500*man-days / 750*days), 90*tons of Cargo Hold, 200*tons of Vehicle Dock, 90*tons of Hangar Bay
[2] Plus 4 in Hibernation Chambers, [3] Crew Requirement (9 total): 4 Control Stations (1 Captain/Pilot, 1 Operations
Officer, 1 Chief Engineering, 1 Navigator/Comm/Sensor Operator), 1 Technician, 2 Entertainment, 2 Lab Workers
[4] Modular
FUEL USED: [5] Fissionables, [6] Hydrogen (50 tons)
PERFORMANCE PROFILES: [7] Space Profile #1


AUXILIARY CRAFT

Qty.                   Ship                     Cost         Mass  
   1  Sling Liner Passenger Barge                  $216k       30
   1  Kobold Work Bug                          $1.12515M       30
   1  Aurora Orbital Transfer Vehicle (OTV)      $811.6k       30

HABITATS

Qty.   Location             Type           SM         Notes         
   3  Center [C]  Cabin                    +0             6 person
   1  Center [C]  Bunkroom                 +0             4 person
   1  Center [C]  Establishment: Rec Room  +0  20 patrons, 2 staff
   1   Rear [6]   Lab: Standard            +0   2 person, +1 Skill
   4   Rear [6]   Hibernation Chamber      +0           4 chambers
   1   Rear [6]   Sickbay                  +0      1 bed; +2 Skill
   1   Rear [6]   Minifac: Fabricator      +0         $500 per Hr.
   1   Rear [6]   Steerage Cargo           +0               5 tons

Created using GURPS Spaceship Design Spreadsheet v2.0 RC 7. GURPS Spaceships Design Spreadsheet is copyright © 2009-2013 Eric B. Smith. This spreadsheet is based on information contained in the GURPS Spaceships series of books.

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