Youre Going to Burn it Anyways

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Youre Going to Burn it Anyways

• Expendables and Bulk Cargo Lift
• George William Herbert
• Retro Aerospace
• Presented at Space Access 2004

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Bulk Cargos

• Propellant and related (LOX, LH2, Propane,
  Methane, Kerosene, Hydrazine, N2O4, Xenon,
  Nitrogen, Helium, Water, )
• Life Support Consumables (Water, Oxygen,
  Nitrogen, Food, Entertainment)
• May be shipped in a form different than use form
• Similar cargo types
• High volume spare parts, components, etc
• TBD

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Some Economics Considerations

• Bulk Cargo is, relative to any credible launch
  cost, Free
• Excepting the insane exotic propellants Please
  report to torture chamber before proposing their
  use.
• Nobody cares if you lose a load.
• Opportunity Costs of lost operations and schedule
  are more painful, though.

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Bulk Cargo Users

• Payload is NOT a standalone vehicle
• Must be gently delivered to users
• International Space Station
• Orbital Hotel
• Orbital Assembly Point or Fuel Depot
• Luna
• Mars
• Note that User is probably in High LEO or beyond

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Orbital Fuel Depot

• Probably at 0-28 deg
• Altitude TBD
• High payload penalty up
• Low drag penalty continuous
• Optimum depends on many component factors in
  launch costs and rates
• Probably manned robots not dexterous enough
  (yet)
• General purpose station
• Dedicated Fuel Depot only

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Reusable Vehicle Characteristics

• Expensive to develop, and long time
• Cheap(er) marginal flight costs
• Must be highly reliable to be safe and economic
• Likely manned
• Fewer stages, and high payload penalty beyond low
  LEO

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Expendable Vehicle Characteristics

• Cheap(er) to develop, and shorter time
• More expensive marginal flight cost
• Traditionally highish reliability, but
  reliability vs cost tradeoff is fairly easy
• Probably unmanned
• Typically more stages and moderate payload
  penalty beyond low LEO

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Reusable vs Expendable

• Reusables are
• Expensive to develop, and long time
• Cheap(er) marginal flight cost
• Must be highly reliable to be safe and economic
• Likely manned
• Fewer stages and high payload penalty beyond low
  LEO

• Expendables are
• Cheap(er) to develop (shorter time)
• More expensive to operate, marginal cost
• Traditionally highish reliability, but could be
  lower cost and lower reliability
• Probably Unmanned
• Typically more stages and moderate payload
  penalty beyond low LEO

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Reusable v Expendable vBulk Cargo Requirements
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ELV Cost vs Reliability Trades

• Single string
• Lower margins
• Simpler systems
• Design for disposability systems
• Possibly recover the GNC equipment

• Big Dumb can be high reliability, but doesnt
  have to be, and it will save noticeably on cost
  per launch and cost per delivered pound.
• Overall Bulk Cargo mission may optimize that
  direction or not
• But at least its an option

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Orbital DeliverymanA Mixed Blessing

• Hig her reliability
• Easier rendezvous and docking, maybe
• Autonomous vehicles are flight proven.
• But make operations people nervous. Were doing
  it anyways
• Robots may be more reliable than people.

• Astronauts delivering water are not sexy
• Astronauts dying delivering water are definitely
  not sexy
• Astronauts are heavy
• Astronauts are impatient

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To Tug or Not to Tug

• An Orbital Transfer Vehicle (OTV) or Space Tug
  may optimize the system
• Space-based, platform cargo platform
• Or, Carried with each payload
• Reusable Tug
• Expendable Tug
• Tug will need accurate guidance, control,
  maneuvering, and high reliability
• Characteristics push towards reusable

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How Big a Tank?

• Each unit delivered requires an OTV run or a OMS
  capable RLV flight
• OTV cost only weakly dependent on size
• At small total volumes it wont matter
• Past that point, if multiple OTVs or RLVs are
  required, drives up cost.
• Smaller units drives cost up a lot faster
• Bigger units lower flight rate
• There is no single optimum without looking to
  Launch Vehicle Initial and Marginal costs for a
  LV concept

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Docking vs Berthing

• Hard docking requires hard, strong vehicles
• Berthing requires cooperative target or
  arm/grapple on the Tug
• Berthing is probably cheaper, easier, and safer
• Even if we need an arm on the OTV

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Conclusions 1

• Expendable launch vehicles are a better match to
  Bulk Cargo in the nearterm
• Theyre available already, no dev cost.
• Lower marginal prices if you do dev.
• Little penalty if you lose a vehicle.
• User project can get on with its space
  operations sooner and more directly
• Launch solution development is not the critical
  path.
• Can evolve towards cheaper ELVs with moderate RD
  investment and NO schedule hit.

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Conclusions 2

• Its not clear if manned delivery makes sense or
  not.
• Makes much less sense if you trade away
  reliability to lower cost, which may
  significantly lower overall cost
• May simplify operations, may not reliability of
  automated systems is an issue
• Getting people into space is the point, though
• Need to look at specific user and mission

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Contact Info

• George William Herbert
• Retro Aerospace
• gherbert_at_retro.com
• www.retro.com

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