OCTANE: A LEO Fuel Cache-Tanker

Ivan Figueroa

Pioneers of a Familiar Frontier

• Space Policy Directives (SPD 1-3) - Return to the Moon with a Mars forward agenda
• Private enterprise to play a major role

• Forefront of this new approach is the Lunar Gateway (LOP-G)

A New Gilded Age in Space?

• Commercialization of Space is just around the corner
• Space could be a $3 Trillion dollar industry by 2040s^[1]
• Government push of a Commercial LEO Development Program
• Includes funds to “stimulate the development of private sector entities & capabilities”
• Proliferation of launch systems in the past few years, even more to come

The Issue Facing Us Today

• Doing anything in Space is driven by Delta-V --- i.e. fuel
• A majority of the fuel needed is just to get to Earth orbit --- “Once you get to Earth orbit, you’re halfway to anywhere in the Universe” –Robert Heinlein
• 70% of the mass we move is propellant [1]
• Easy access to plentiful fuel is the key to driving large scale infrastructure at and beyond LEO

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The Fuel of Innovation

“I ascribe the success of Standard [Oil] to its consistent policy to make the volume of its business large through the merits and cheapness of its products….It has placed its manufactories at the points where they could supply markets at the least expense.”

-John D. Rockefeller

• A market gap exists between now and when more permanent fuel storage can come available
• There is opportunity to supply a burgeoning space infrastructure industry with fuel

Desired Characteristics

• Short-term fuel storage capacity
• Basic Subsystems --- storage, rendezvous, power, propulsion
• Ideally should be “Plug-and-Play”
• More akin to an aerial tanker and less of a space tug
• Scaled to meet the demands of operations

Depot/Cache Concept

Propulsion

Thermal Control & MLI

Based on available dimensions and limitations of a Falcon 9 v1.2

What fuel to use in the Cache?

• Cryogenic: LOX/H2, LOX/RP-1
• Pros: Best performance --- common use
• Cons: Requires cooling equipment --- high boil-off rates with long term use
• Cost of producing liquids is low, (~$4-7/kg for LH2 and $0.16/kg for LOX) ^[3]
• Real downside comes from long-term storage at low temps and high pressures
• Non-cryogenic: Hydrazine, MMH/NTO
• Pros: high densities at reasonable temp/pressure --- good performance (Isp ~310sec) --- common use and mature technology
• Cons: toxic --- hazardous to handle --- very volatile

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In the very short term, we can use fuel-oxidizer combos like MMH/NTO

How Useful Would Our Cache Be?

Bundles can be assembled in LEO with support bracings and docking adapters

Applications

ADR

Servicing

Orbit Transfer

LOP-G Resupply / cargo

Lunar infrastructure/ cargo

Evolution of the Fuel Cache/Depot

Merits and Limitations

Pros:

• Harness existing hardware/technology
• Funding not solely dependent on governments
• High technology readiness
• Design simplicity

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Cons:

• Elasticity of demand for this type of mission is unknown, could be inelastic
• Expendable hardware has its downsides
• Non-cryogenic fuels = less performance and larger fuel requirements
• Toxic fuel

Direction of Future Efforts

• Incorporate fuel transfer systems to increase reusability
• Develop cryocoolers and thermal control technologies to switch to cryogenic fuels
• Develop larger capacity depots with use of super heavy launchers

Sources

[1] - “Propellant Depot Requirements Study Status Report”, HAT Technical Interchange Meeting, NASA, July 21st, 2011

[2] - Frank Zegler and Bernard Kutter,“Evolving to a Depot-Based Space Transportation Architecture”, AIAA 2010-8638, AIAA SPACE 2010 Conference & Exposition

[3] - “Missile Fuels Standard Prices Effective Oct 1, 2007.”, Defense Energy Support Center, Fort Belvoir, Virginia, July 2007. [http://www.desc.dla.mil/DCM/Files/MFSPFY08_071107.pdf. ]

[4] - Condon, J. , Williams J., et.al “Libration Point Mission Design Considerations”, Visual Presentation, JSC-CN-30863, NASA Johnson Space Center, Mar 27, 2014

[5] – Whitley R., Martinez R., “Options for Staging Orbits in Cis-Lunar Space”

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Backup Slides

Possible Launchers

Delta-V Relations^[5]

Delta-V to Mass Ratios^[4]

Bundled Cache Mission: Lunar Gateway

Concept Assumptions

• Accelerated development goals of Gateway compared to current timeline of 2026
• Active launchers are not phased out during the present to 2022 timeframe
• Launch vendors maintain current production but there is room for growth
• Priority given to supporting Lunar Gateway and lunar orbit infrastructure
• Mission might consist of lunar free-return trajectory, orbit injection and orbit inclination change

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