1. Space Tug Propellant Options AIAA 2016-vvvv
52th AIAA/SAE/ASEE
Joint Propulsion Conference
Salt Lake City, Utah
John W. Robinson, Propellant Supply Technology, Boeing (ret.), Seal Beach, California
July 25-27, 2016

2. Achieve affordable exploration & habitation of space
Space Tug Propellant Options
Major Goals
Achieve affordable exploration & habitation of space
Evolve to independent propellant supply and operation in space
Preserve Earth resources
Develop space resources … minimize contamination
Provide independent propellant supply and service platform for future space operations.
Space based operations independent from Earth resources
Evolve independently from Earth to total Space Based Operation Complexes
Identify or produce space resources for sustained independent operation
Locate resources, develop propellant acquisition plan and produce propellants
Demonstrate long term in-space operation
Long term propellant storage capability
Propellant transfer with repeated on orbit refueling.
Utilize LOX/LH2 for early space infrastructure development
Evolve to space based resource utilization
Clean pollution free liquid rocket propellants

3. Where do you find usable propellant resources?
Space Tug Propellant Options
Where do you find usable propellant resources?
The wide range of locations to support suggest many sources for space resources
Space Operation Regions
Near earth: Low Earth orbit (LEO), geosynchronous orbit (GEO) and Global Positioning Satelites (GPS).
Moon- Earth: Resources are abundant on the Moon & Astoroids for Moon-Earth based operations including Low Lunar Orbit (LLO) and Earth-Moon Lagraaangian Points
Planetary regions: Mars, Jupiter & Europa; and, Saturn & Titan are varied in resources
Space Resource Development
Mining and commercialization of propellant in space required

4. What is needed to establish in-space propellant resources?
Space Tug Propellant Options
What is needed to establish in-space propellant resources?
Propellant and in-space material source availability including parts manufacturing
Assure adequate inputs available for thorough evaluation process
Thoroughly defined design concept to meet desired cost goals
Moon-Earth regional resources
Near term LOX/LH2 to be provided from Earth
Long term hydrogen & oxygen from Moon
Liquid propellants with varying mission duty cycles (excludes hybrid & solid)

5. Space Tug Propellant Options
DESIGN APPROACH & KEY REQUIREMENTS
Evolve capability with minimum energy access to initial space complex to support space exploration & habitation. (Moon- Earth Lagrange point basing )
Robotic concept w/ propellant development, demonstration & qualification (for manned rating)
Long term space operation.
Pollution free exhaust environment.
TECHNOLOGY NEEDS
Long life universal engine
LOX/LH2 engine that can adapt to alternate space propellants
Earth supported immediate needs
Utilize regional resources for planatary exploration

6. PROPELLANT AND PROPULSION
Space Tug Propellant Options
PROPELLANT AND PROPULSION :
Liquid Propellant System
Varable thrust / burn time capability
Space resource availability
Moon or asteroid for moon –earth region
Desired characteristics
High performance propellants.
Polution free exhaust products.
This chart now shows that when we select the element failure rate as close to 1.5E-6 (chart actual value is E-6) we now have a new System Reliability value of and reading across to the probability of success value close to 0.98 and reading up to the element limitation value it is now 9,100 maximum while allowing one or less failures to occur during the 16 hrs time interval.

7. Provide for the following functions:.
Space Tug Propellant Options
Overall Mission Support Requirements
Provide Propulsion and Reaction Control servicing (insertion/circularization, de-orbit & trans-lunar/mars injection)
Provide for the following functions:
Propellant storage
Propellant management
Propellant/hardware thermal management
Engine control & health management
Complex power generation.
With this chart we are using this same given requirements, but selecting an element failure rate more achievable such as 1.5E-6. It can be seen from the column on the far left (element failure rate) when we select the 1.5E-6 and move across to a MTTR close to our requirement of 5 hrs. we select a MTTR of 3.37 hrs. and read up to the availability value at the top of the table to be 99%.
Now let’s move on the next chart and see what our new elements limitation would be using this new element failure rate.

8. Service Complex Design
Space Tug Propellant Options
Service Complex Design
Designed for long term space operation up to five years without resupply.
LOX/LH2 can enable self-pressurization with GLOX/GH2 tanks reaction control. (minimize fluids)
Engine heat exchanger or the O2H2 burner drawing directly from the LOX and LH2 tanks.
Lithium-ion batteries for primary power (no on-orbit fuel cell servicing or solar array)
Combination of the low self-discharge rate of the lithium-ion batteries and the low boil-off rate will enable dorment extended periods while being immediately available for operation.
LOX/LH2 main propulsion demonstrated successfully on many upper stages.
Micrometeoroid/space debris shields and advanced tank insulation scheme.

9. Early Mission Capabilities
Space Tug Propellant Options
Early Mission Capabilities
Early introduction of the in-space architecture supporting “Roadmap for Long Term Sustainable Space Exploration and Habitation”.
Primary missions:
Placement of objects in near earth locations
Retrieval of LEO objects and move to new orbits
Enable Space Based Enterprise (transportation support, re-supply, etc.)
Establish in-space propellant transfer & universal docking
Secondary missions:
Hardware demonstration for long term in-space use

10. Space Tug Propellant Options
OPERATIONAL SUMMARY
Service Complex an essential element of spaced based architecture will provide:
Infrastructure necessary for the commercial expansion of space activities.
Working vehicle to provide support in developing in-space architecture.
Establish routine propellant transfer for continual operation in space.
Service Complex can be developed using current technologies and operational deployment will provide:
Substantial improvement in mobility and logistics throughout the Earth-Moon system.
Infrastructure element that is paramount to encouraging commercialization in space.
Capability to close the business cases on several applications such as
Satellite servicing
Space debris removal
Mining the moon or the asteroids.

11. Conclusions Space Tug Propellant Options
Technology and resources exist to initiate an evolving Service Complex in Earth moon region
Implementation will provide routine space operations throughout the Earth-Moon system.
Operational deployment will provide substantial improvement in mobility and logistics.