Sa08 Prop Depot Panel Frank Zegler

Cryogenic Propellant Depots for the Real World March 27 2008 United Launch Alliance

Depots Amplify Performance
EDS Topping from orbital depot amplifies lunar payload
EDS is half full in LEO for ESAS
Accommodates mission delays or high propellant boil-off
Small variations in fabrication have large impacts to tank heating
Untestable prior to launch
Centaur experience shows 2:1 variation in heating, same mission
Likelihood of launch delays is historically very high
Opens the door for more capable exploration architectures
Indefinite surface stays, autonomous asset/consumables delivery
Simplified vehicle design, increased systems commonality
Payload Increase, mT Propellant Transfer Mass(mT) Pictures Credit: NASA 123126 EDS LSAM CEV

Historic Propellant Depot Paradigm NASA 9902019
Propellant transfer has been associated with:
Large scale propellant depots
Zero Boil off fluid transfer
Zero Boil off Storage
Propellant depots imply:
Large infrastructure
Zero-G cryo fluid management
Currently at low TRL
Huge initial hurdle to cryo fluid transfer implementation
Historic Architectures are an Insurmountable Barrier

Simple Cryo Depot Concept
Exploration is mostly about moving LO2 around
Simple depot sidesteps barriers
Single propellant (LO2), single unit, single launch
Based on existing tanks/upper stages
Simplified thermal management
Geometry isolates cold and hot elements (long conductive paths);
Sun Shield, MLI, vapor cooling
Liquid Gas Gas Solar Array Sun Shield Hot Equip Deck Dock Port Hot Side Cold Side Rotational Settling SUN
Settled (rotational) propellant management
Settled Propellant transfer
Gas reservoir provides thermal barrier, expulsion gas

Two Obvious Options
Depot based on Modified Upper Stage
Least possible Non-recurring investment
Compromised onboard systems
Bound to a single launch supplier- minimal competition
Inevitably leads to higher recurring costs
Restricted propellant capacity
Depot as a Dedicated Payload
Higher Non-recurring Investment
Optimized onboard systems
Much larger propellant capacity, greater utility
Supplied/replenished by multiple launchers
Enables direct competition for orbital propellant delivery
Best chance for market-driven lower costs

Upper Stage Based Depot 1 or 2 additional burns for phasing
Existing Vehicles deliver 12-16 tons: Lunar cargo increase 3-4t
Baseline ACES delivers 17-25 tons
Extended tank designs deliver 40-42 t
ACES BASELINE 200 nm circ orbit 1 or 2 additional burns for phasing 1 200k 1 2 2 4 4 6 6 200k 1 1 Number of RL10 engines

Upper Stage Based Depot Integrated 6 DOF LO2/LH2 Attitude Control Solar Power System Baseline ACES Upper Stage, 41t Propellant Load at Launch Deployable Multiple-Petal Open-Cavity Sunshield (2 petals removed for clarity) EDS docking interface Long Duration Avionics with Rendezvous, Docking, Propellant Mgt functions Vapor Cooled Depot Systems Interface LO2 Tank
A dedicated ACES on Atlas HLV delivers 25t Propellant to LEO
Equivalent to Altair Cryogenic propellant load (24t)
LH2 Tank

Dedicated Depot Depot shown uses Identical sunshade to ACES upper stage version
Launched partially filled to maximum launcher capability
Refilled via commercial LO2 delivery to LEO
Falcon, Delta, Atlas, Ariane, SSTO/RLV
Capacity:
230 t LO2 or 167% of EDS capacity
14.3t LH2 or 63% of EDS capacity
Extended Upper Tank (LO2 or LH2) Truncated Lower Tank (GO2 or GH2)

Depot Location
LEO location poses orbital inclination/launch opportunity limitations
Complex mission planning
Depots in Lunar orbit or at Earth-Moon L1/L2 have even greater utility
Easier thermal management (Solar heating dominated)
Propellants confirmed safely delivered at destination
Thermal performance is known via daily operation
Delivery of unmanned Altair to LLO an obvious next step
Drastically reduces performance demand for ARES, EDS, Altair
ARES V can be far simpler- 65-80t @ LEO vehicle
Altair optimized for lunar operations- no LOI function

Depot Technologies are In Hand
Autonomous Rendezvous and Docking
XSS-11 and Orbital Express show ARD to be straightforward, cost effective
Cryogenic Propellant Storage, Thermal Management
Settled-Propellant design is critical to eliminating complexity and risk
Existing designs/data/analyses directly applicable
LO2-only design decreases thermal storage complexity and risks
Foundation for LH2-only systems as needs evolve
Analysis shows 0.01%/day boil-off is possible, supporting long, passive cryo storage
Cryogenic Propellant Gaging, Interconnection, Transfer, Control
Settled operation takes all the risk out
Transfer identical to engine propellant feed
High capacity interconnects based on slip-joint ducting
Mass gaging simple and accurate without exotica
Vent control based on existing designs, proportional valving

ULA Technology Development
Gas Strut Deployable Sunshield
Full scale demo in 2007. Continued 2008
Intermediate Bulkhead Load Bearing Insulation
Compressive load cryostat completed, testing underway
Insulation selection 2008
Bulkhead concept definition 2008
Rotational Propellant Settling Flight Demonstration
Using 11kLbm residuals on Centaur spring 2008
H2 Para-Ortho Hardware Demonstration
Completed baseline demo, more work 2008
H2/O2 Catalytic Thruster
>1 hour hotfire time 2007, continued development 2008
Integrated H2/O2 propulsion/fluids system
No Ghe, No Hydrazine, Long Duration capable
Concept validated 2007, continued work 2008
Cryogenic proportional valving, Cryo-compatible regulator array
Development start 2008
Ullage Liquid

Cryo Transfer Extensibility
Transfer of cryogens is mandatory for exploration
Real exploration implies long stay durations, indeterminate mission design
Routine handling of tons of LH2 and LO2 for fuel cells, ECLSS
Scavenging of propellants from expended stages and landers
Allows practical sizing for vehicles with wider range of missions
ISRU has large-scale cryogenic propellant handling at its heart
Mars implies routine and unlimited fill/transfer/refill operations
Accumulation of Mars-bound assets at L1/L2 is essentially mandatory for even a skeleton exploration crew
Near-continuous pre-departure propellant delivery missions
Propellant Synthesis, densification and storage on the surface
Orbital and endoatmospheric operations
Mars is a near-perfect SSTO location
Replenishment of Earth-return assets in Mars orbit
Enhances science missions through orbital replenishment and servicing
This Technology is Essential

Summary
Propellant transfer is a powerful tool
Amplifies existing ESAS capabilities (doubling or tripling of cargo)
Removes unrealistic demands on proposed vehicle designs
Hardware simplification  lowered risk  lowered cost  faster schedule  higher rate  better science  more popular support
Simple depots can be done NOW
Single propellant, single launch, single unit
Simple, proven thermal management, propellant xfer techniques
Provides a mission all launch suppliers can participate in
High density, low intrinsic value cargo with simple mission
Ideal cargo for first generation SSTO/reuseable vehicles
SSTO vehicles have low inherent lift capability but depot demands provide high launch rate for economic operations
Must support multiple SSTO vehicles for viability
Sets the stage for later LEO lift of propellant for Mars missions

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Sa08 Prop Depot Panel Frank Zegler

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Sa08 Prop Depot Panel Frank Zegler — Presentation Transcript