Deputy, Washington Operations Highly Efficient In-Space Propulsion for a Capabilities-Based Exploration Architecture November 3, 2011 Joe Cassady Deputy, Washington Operations joe.cassady@aerojet.com

Aerojet HLPT Architecture Study Aerojet was one of the companies selected to study exploration architectures for NASA MSFC Focus was on affordability and sustainability Need to incrementally develop capability to stay within budget Lox-RP booster propulsion for launch identified commonality with multiple users provides performance required to achieve 130MT SLS Several in-space propulsion technologies identified Solar-electric propulsion for cargo transport Nuclear-thermal propulsion for human transfer ISRU for sustained human operations at Mars Focus of this presentation is on near-term in-space technology Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this proposal.

Launch Delta V versus In-Space Delta V More emphasis has typically been on Earth-to-orbit (launch) As we aim to go further, the emphasis should switch Need strategies to reduce the amount of propellant required for in-space transportation For GEO birds half the launch mass is propellant Propellant costs just as much to launch as useful stuff! New paradigm needs to include waypoints and incremental capability increases to match budget constraints We are not going to Mars right away, it’s too big a leap SLS and MPCV decisions have laid a good foundation, But now we need to think about what to build on that foundation Distribution Unlimited / Public Release Approved

For Beyond LEO Missions, In-Space Dominates Less than 1/3 of the total delta V required is Earth to LEO

Which Would you Rather Use to Move? Sports cars are cool and fast, but for hauling freight you want a truck Distribution Unlimited / Public Release Approved

SEP Tug Used to Preposition Cargo ISP = 3000 Sec Prepositioning Cargo with High Performance Solar Electric Propulsion Significantly Reduces Costs SEP Tug Used to Preposition Cargo ISP = 3000 Sec IMLEO Reduced by 60% Compared to Cryo Cargo Pre-positioned Cargo Exploration Habitats Consumables for exploration and return Earth Return Stages/Propellant Exploration Equipment Landers and Ascent Vehicles ISRU plant 150 kW SEP Module SEP is Required for a Sustainable Exploration Cargo Transportation System

NTR and Lox-Methane for Crew and Lander Propulsion Complements SEP First ground demonstration in 2020 First demonstration flight in 2023 Short Duration Human Flight in 2027 Key Characteristics High ISP (900+ seconds) Thrust = 20,000 lbf Leverages NERVA and ROVER development work Utilizes existing turbo-machinery Lox-Methane Lander Propulsion Leverages NASA investment from PCAD Can take advantage of ISRU for Mars Soft cryo reduces long term storage issues Key Characteristics Isp = 350 seconds Thrust = 35,000 lbf Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this proposal.

Architecture Studies Recognize the Value of SEP STCAEM (Boeing 1991) HEFT (NASA 2010) Heavy Lift Propulsion Technology (Aerojet 2011)

Operational Use of EP Has Dramatically Expanded In 1996, there were less than 30 spacecraft flying EP, mostly low power resistojets ( < 1 kW). Today, more than 200 spacecraft fly a a variety of EP devices at power levels up to 5 kW. Then (1996): Avg S/C Power – 8 kW Avg. S/C Life – 7 years Now (2011): Avg. S/C Power – 15 kW Avg. S/C Life – 14 years

Power Technology Is Also Dramatically Improving Dramatic Improvements in solar array technology in recent years Efficiency - from 29% to 42% in past 9 years (lab) - 28% flight production (2x ISS) Power density - 170 (ISS) to 280 W/m2 (SLA - Entech) in 5 years Array specific mass - 45 to 180 W/kg since 1998 - 350 W/kg projected Extensive Ongoing Research, continuously improving performance and cost in photovoltaic power production

Propulsion Developments to Support HSF Common element of many architectures is a high power solar electric propulsion (SEP) space tug Power levels between 300 kWe and 1 Mwe at the vehicle level Thruster modularity needs to be at the 50 – 150 kWe level NASA GRC Tank 5 Thruster development work has been done at power levels up to 100 kW; 5 kW thrusters are flying on AEHF 150 kW 5 kW Images courtesy NASA

Array Technology and Mechanisms Exist Aurora Solar Array Structure GEO Comsats now routinely flying 20 kW arrays ISS arrays provide over 150 kW at full illumination Old cell technology (~ 12%) Better than 2x power with improved PV cells Tailorable stiffness New array technology for the future (300+ kW) Square rigger (ATK Goleta) FAST(Boeing) Solarosa (ENTECH) Partially Deployed Square Rigger Array Structure Current array / mechanisms can meet full scale requirements when combined with triple junction cells Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this proposal.

SV Configuration for SEP Demo SEP Spacecraft configured for a variety of launch vehicles using standard 32-inch adapter interface Falcon 9 Delta IV Atlas V 26

AEHF Provides Existence Proof 4.5 kW Hall thrusters used on AEHF-1 for orbit transfer “rescue” $2B asset will have full lifetime and mission utility 15

Capabilities Based Evolution Missions: Prepositioning, Resupply, Servicing Missions: Prepositioning, Resupply, Return Missions: Cargo transport Missions: Debris Remediation, Servicing, Satellite Rescue, Military 30 kW Class SEP Tug 90 kW Class SEP Tug 200 kW Class SEP Tug 300 kW + SEP Tug

Summary Exploration missions will require large amounts of material to be moved over vast distances Analogy to earth surface is freight shipment via rail and ship SEP provides tremendous leverage for all exploration missions beyond LEO Consistent finding of architecture studies is that IMLEO is key FOM Other proposed solutions do not reduce IMLEO as much as SEP Technology readiness is high for all subsystems – need to do an integrated demonstration Provide confidence to potential users that critical operations such as RPO and spiral orbit transfers will not be an issue Demo can proceed now with technology insertion as it becomes available Incremental capability comes on line when needed to support more ambitious missions – this maintains affordability