MinMars/InSpace Transportation

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This section requires further editing to include all previous efforts.

Repository of Working Models

http://svn.developspace.net/svn/minmars/users/arthur/Transportation/

Minimalist Transportation Concept

Transportation Challenges

  • How do we transport crew and cargo to the Martian surface using 25 mt launch vehicles?
    • 25 mt is “worst-case scenario”
    • Larger payload capabilities would facilitate transportation and also lead to scaling benefits
  • Specific challenges:
    • Launch and LEO orbit assembly
    • Mars aerocapture and EDL
      • Ballistic coefficient (entry body mass, diameter, shape)
      • Altitude at Mach 3 / aeroshell separation
    • Propulsive descent (800 m/s assumed for now)
    • Final landing GN&C, landing error reduction
    • Hazard avoidance
  • Falcon 9 Heavy assumed as reference LV
    • ~28 mt to 300 km LEO
    • ~4 m x ~10 m cylinder of usable volume in shroud

Mars Aerocapture and Entry Vehicle

  • Entry vehicle is based on conic blunted body
    • 20 degree side-wall angle
    • Drag coefficient: ~1.6
    • L/D: ~0.3
  • Total mass is 12 mt, leading to a ballistic coefficient of around 600 kg/m2
    • Mach 3 altitude ~ 5 km
  • Final descent propulsion based on MMH / N2O4
    • Isp = 320 s
    • 8 tanks (4 fuel, 4 oxidizer)
  • Cargo to surface: ca. 5 mt

Cargo Transportation Concept

  • Transportation concept based on dual blunt-shaped entry bodies
    • Reduces ballistic coefficient per entry body (~ 600 kg/m2)
    • Allows for simple blunt-body shape
  • Entry bodies are launched together with additional cruise systems
    • Solar arrays, batteries, radiators
    • Entry bodies separate prior to aerocapture and aeroentry
  • 2 Earth departure stages are launched after the entry bodies
    • Stages dock to entry bodies for dual burn Earth departure
  • Initial analysis indicates that ~25 mt can be injected towards Mars using LOX / kerosene stages
    • ~10 mt useful cargo mass on Mars surface (~ 5 mt per entry body)
  • Crew transportation with entry body (cargo) and additional transit habitat
    • 2 sets of solar arrays, batteries, and radiators
    • Transit habitat is jettisoned prior to aerocapture
  • 2 Earth departure stages are launched separately and docked
    • Dual burn Earth departure
    • LOX / kerosene propulsion
  • Initial analysis indicates that 2-3 crew can be delivered to Mars surface this way
    • Crew can be sustained for 30+ days on surface after landing
    • Unpressurized mobility delivered with crew

Transportation Results & Future Work

  • 4-6 crew can be transported to Mars with 6 Falcon 9 heavy launches
    • Launch cost of ca. $ 600 Mn (ca. $ 100 Mn per launch)
  • 3 Falcon 9 heavy launches can deliver a minimum of 10 mt of useful mass to the Martian surface
    • Equivalent to 26-month consumables demand for 4 crew
  • Forward work:
    • More detailed design of aeroshell and descent stage
    • More detailed design of Earth departure propulsion
      • Including propellant type trade
    • Investigation of different entry body shapes

Transportation Update

  • Previous transportation strategy was based on use of ~12 mt aeroshells with diameters around 5 m
  • This leads to a significantly increased number of aeroshells that need to be built, as well as to reduced maximum volume of items that can be transported to Mars
  • Analysis was carried out to determine whether it is possible to use a single ~24 mt aeroshell

Aerodynamic Properties

  • Basic shape is blunted cone with 20-degree side-wall angle
  • Achieves L/D of 0.3 at 18.5-degree angle of attack
  • Drag coefficient of ~1.5 at 18.5-degree angle of attack
  • Shape is similar to SpaceX Dragon capsule
    • May be possible to utilize aerodynamic database from Dragon
    • Possibly use Dragon derivative?

Preliminary Transportation Cost Assessment

  • Falcon 9 Heavy [FY 2008 $]
    • $ 94.5 Mn per shot for LEO mission
  • Lander costs [FY 2004 $]
    • Dry mass: 2453 kg
    • Development: $ 1482 Mn
    • Production (1st unit): $ 112 Mn
  • Aeroshell costs [FY 2004 $]
    • Dry mass: 8000 kg
    • Development: $ 2839 Mn
    • Production (1st unit): $ 245 Mn
  • TMI stage [FY 2004 $]
    • Dry mass: ~5000 kg
    • Development: $ 560 Mn
    • Production (1st unit): $ 32 Mn
  • Approximate marginal cost for transporting 10 mt to the surface of Mars:
    • (3 x 94.5 + 2 x 32 + 112 + 245)*1.2 = 845.4
    • $ 84540 / kg on the surface of Mars

Concept Overview for 2 mt Case

  • “2 mt case”: integrated payloads of no more than 2 mt can be landed on the surface of Mars; extension of current Mars EDL technology
  • Cargo transportation
    • All cargo packages are landed on the surface of Mars using scaled-up MSL-type vehicles
    • Each cargo package and the associated cruise stage and EDL system is launched and injected towards Mars using an EELV-class launch vehicle (Falcon 9 heavy, Delta IV heavy, Atlas V heavy, etc.)
  • Crew transportation
    • Similar approach as for 10 mt case, but different hab / EDL design
    • Mars Transfer Vehicle is assembled in LEO out of 3 payloads of ~25 mt
      • 1st payload: habitat + Mars entry vehicle (same entry vehicle as for cargo)
      • 2nd and 3rd payloads: each one ~25 mt propulsion stage for TMI
    • 2 crew are transported using this transfer vehicle