Presentation on theme: "Jonathan Goff, Masten Space Systems"— Presentation transcript:
1 Near-Term Propellant Depots: Implementation of a Critical Spacefaring Technology Jonathan Goff, Masten Space SystemsBernard Kutter and Frank Zegler, ULADallas Bienhoff and Frank Chandler, BoeingJeffrey Marchetta, University of MemphisPresented by Jonathan Goff at AIAA SPACE 2009Pasadena, CA September 17, 2009
2 What are Propellant Depots Facilities in space that can receive, store, and transfer propellants and other fluids to visiting vehicles.Can be located in LEO, at Lagrange Points, around other planetary bodies or at any other points of interestCan be supplied from earth, offworld sources, and maybe even from planetary atmospheresCan handle different sorts of fluids ranging from LOX/LH2 cryogenics to “space storables” to hypergolsCan range in size from a Falcon-1 launched single-use fuel tank with a docking adapter to massive, ISS-sized transportation nodes.
3 Historical Solutions to the Propellant Logistics Problem Rocket-powered spaceflight isn’t the only historical example of logistically challenging transportation.Similar Historical AnalogiesAntarctic ExplorationFood/Fuel CachesSteam-powered NaviesNaval Coaling Stations and ColliersSteam-powered railroadsCoaling and watering stationsLong-range jet powered military planes and helicoptersMid-air refuellingThe historical solution to this problem has always been to cache propellants along the way.Early visionaries of the Space Age, including von Braun, recognized this reality as well.Propellant Depots are the Solution to Space Transportation Logistics Challenges Most In-line with Historical Precedent
4 Propellant Depot Questions Key Questions about Propellant DepotsAre they technologically feasible at this time?How would you go about doing depots?What’s the best way to use them in a space transportation architecture?What sort of missions/capabilities to depots enable?How do they compare economically versus other options?How do you handle the logistics of running a depot?} This Paper
5 Overview Prop Depot Technologies Depot Concepts m-gravity Cryo Fluid ManagementThermal ControlRendezvous and Propellant TransferDepot ConceptsDepot Technology Maturation ToolsConclusions/Future Work
6 Propellant Depot Technologies m-gravity Cryo Fluid Management While mg fluid handling is feasible, and sometimes desirable, settled handling is much higher TRLThere are many settling options, including: inertial (propulsive), tether-based, and electromagneticInertial settling is highest TRL, with decades of operational experience (Saturn SIV-B, Centaur, DIV-US, Ariane-V, etc)Fluid handling options interact with other depot design decisionsED-tether based systems can use tether for reboost and settling.Inertially settled depots can use boiloff from passive thermal control systems for settling and stationkeeping.
7 Propellant Depot Technologies Thermal Control Passive versus Active, Zero Boiloff (ZBO) Thermal ControlZBO propellant storage is technologically feasible, and greatly simplified by settling propellantsWith settled propellants, active cooling is a lot closer to terrestrial experience than in mg conditions.Passive systems can tend to be a lot simpler and more reliable than active cooling systemsGood passive thermal control is important even if active cooling is usedLowers the amount of heat that has to be actively rejectedActs as a backup in case of problems with active coolingInteresting Observation #1: Boiled propellants can be reused for stationkeeping propulsive purposes, meaning that for LEO depots, ZBO might not be necessary.Interesting Observation #2: Many of the features that make LH2 a headache for long-term storage make it useful in multi-fluid depots—LH2 is a wonderful “heat sponge”Interesting Observation #3: Due to stationkeeping demands and the challenging thermal environment LEO depots push you towards a “use it or lose it”, high throughput mode of operations.Interesting Observation #3a: Depots at L-points are more suited for long-term storage and less frequent use.
8 Propellant Depot Technologies Rendezvous and Transfer Recent research into orbital servicing (such as Orbital Express, XSS-11, FREND, etc) has significantly advanced the TRL of needed propellant transfer technologiesEfficient and safe depot operations require extremely reliable prox-ops and transferNeed to minimize possibility of damage to depot or tanker from rendezvous/transfer operationsBerthing using robotic arms or Boom Rendezvous may be preferable to traditional dockingMany options for how to handle propellant deliveryProgress/ATV/COTS-like tanker spacecraftIntegrated-stage tanker spacecraft“Dumb” tankers plus tugsPersonal Preference: Tugs for prox-ops plus dumb tankers (based on or integrated with the delivery stage) with standardized docking/propellant transfer interfacesThe most expensive bits get reused multiple timesThey don’t have to be launched every timeMinimizes the amount of engineering an particular launch provider needs to provide propellant delivery servicesMaximizes competition in propellant launch
9 Near-Term Depot Concepts Single-Use “Pre-Depot”Simple, typically 2-launch architectureEnables unmanned and limited manned exploration missions using existing and near-term EELVsSingle-Launch Single-Fluid “Simple Depot”Typically LOX-only, simpler than multi-fluid depotsMuch larger depot capacity than the single-use pre-depotSingle-Launch “Dual-Fluid” DepotLH2 tank is built integral to LV fairing, upper stage LH2 tank is converted to depot LOX tank after deploymentCan be based on existing or stretched versions of existing upper stages, or can be based on future upper stages like ACES or Raptor.Doesn’t require orbital assembly to provide large propellant capacity (75-115mT of LOX/LH2)Sufficient capacity to enable manned exploration without requiring HLVsSelf-deployable throughout the inner solar systemWith a depot at L1/L2 as well as LEO, manned ESAS-class exploration feasible with existing upper stages (with mission kits)Multi-Launch Modular DepotsLargest propellant capacity (200+ mT feasible)Integral robotic arm for easier berthingCan be combined with the above Dual-Fluid concept to reach 450+ mT capacitiesCan be built up modularly
10 Depot Technology Maturation Tools Low-cost, iterative technology maturation and demonstration testbeds reduce the cost and risk of reducing depots to practiceThey enable demonstrating the few first-generation depot technologies that still need demonstrationThey allow other promising options to be evaluatedCRYOTE (CRYogenic Orbital TEstbed) allows long-duration experiments in the space environmentIntegrated with the ESPA ring for use with EELVsLarge experiment volume makes results easier to scale than previous CFM experimentsRelatively frequent flight opportunities as a secondary payloadSuborbital testbeds (CRYOSOTE) flown on reusable suborbital vehicles enable short duration, but very low-cost experimentsmin mg time per flightFlight costs <$50kRapid reflight capabilitiesLarge payload fairing compared to sounding rockets (60+in diameter)Proof-of-concept experiments for various subsystemsPre-fly orbital experiments for debugging before committing to expensive orbital missions
11 Conclusions/Future Work There are several approaches to depots that are both useful for manned space transportation beyond LEO, while also being near-term feasible.Recent development work on autonomous rendezvous and docking, orbital servicing and propellant transfer, orbital CFM testbeds, and suborbital RLVs lower the technological hurdles for implementing depotsAvenues for Future Investigation:A lot of these recent concepts drastically change the picture for how depots would be used in space transportation, which suggests further research into how best to integrate these conceptsMore investigation is needed to evaluate which approaches to tanker design and prox-ops are best, and how the economics of a multi-launch depot-centric architecture compares with alternatives
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