1. Deputy, Washington Operations
Highly Efficient In-Space Propulsion for a Capabilities-Based Exploration Architecture
November 3, 2011
Joe Cassady
Deputy, Washington Operations

2. 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.

3. 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

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

5. 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

6. 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

7. 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.

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

9. 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

10. 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 (ISS) to 280 W/m2 (SLA - Entech) in 5 years
Array specific mass - 45 to 180 W/kg since W/kg projected
Extensive Ongoing Research, continuously improving performance and cost in photovoltaic power production

11. 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

12. 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.

13. 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

14. 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

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

16. 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