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

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

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

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)

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

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 1.4716E-6) we now have a new System Reliability value of 0.954 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.

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 row @ 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.

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.

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

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.

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.