The document proposes a Pluto Orbital Mission that would use a direct fusion drive (DFD) for propulsion and power. Key aspects include: 1) A DFD spacecraft would enter Pluto orbit 4 years after launch to map the surface with a laser-powered lander. 2) The DFD uses a field reversed configuration (FRC) plasma with D-He3 fuel to provide high power for science instruments and laser communications. 3) Experiments at PPPL are developing the FRC plasma and magnetic nozzle concepts, while Princeton Satellite Systems is performing mission design and engineering studies.

1. 1
Pluto Orbiter Mission
Direct Fusion Drive
Stephanie Thomas, PSS
Michael Paluszek, PSS
Dr. Samuel Cohen, PPPL
2015

2. 2
Pluto Orbital Mission
10/7/13
! Enter Pluto orbit 4 years after Earth departure
! Carry a lander
- Deliver power to the lander from the orbiter
! While at Pluto change orbits to cover the entire
planet
! High power available onboard allows advanced
science and communications
- Provide high bandwidth laser communications back to
Earth
! Advance space propulsion and space and
terrestrial power

3. 8/4/15
DFD Reactor Design
KEi
Nozzle

4. 4
PFRC Experiments at PPPL
8/4/15
! Princeton Plasma Physics Laboratory
performing experiments with DOE funding
- Concluded PFRC-1 a, b, c in 2011
- PFRC-2 operating now; goal is to demonstrate keV
plasmas with pulse lengths to 0.3 s
- MNX studies on plasma detachment in nozzle
! Princeton Satellite Systems performing mission
and trajectory design, space balance of plant
studies under IR&D
- Four joint PPPL/PSS patents
3 ms pulse*
0.15 kG field*
e-temp = 0.3 keV*
Machine
Objectives
Goals/
Achievements*
Plasma Radius
PFRC-1 PFRC-2 PFRC-3B
Electron Heating Ion Heating D-He3 Fusion
4 cm
0.1 s pulse*
1.2 kG field
i-temp = 1 keV
10 s pulse
80 kG field
i-temp = 50 keV
8 cm 16 cm
Time Frame 2008-2011 2011-2015 2019-2020
Total Cost $2M $6M $20M
PFRC-3A
Heating above 5 keV
10 s pulse
10 kG field
i-temp = 5 keV
16 cm
2015-2019
$20M
Fuel H H D-3HeH

5. 5
DFD Components
8/4/15
Heat Engine
Shielding
Radiator
Plasma
RF
Generator
SynchBremss
n
Spacecraft
Power Bus
Radiator
HTS Coil Blanket
Coil
Refrigerator
SpaceRF
GeneratorHelium Coolant
Magnetic Nozzle
Auxiliary
Power UnitD
3He
O
2
Electrolysis
D
2
O
Power Recycling
Restart
Gas
Box
3He
Injector
D
Injector

6. 6
Thrust Augmentation
• H or D is used as a propellant- it flows along the magnetic field lines outside of the separatrix;
scrape-off layer (SOL) e- are heated by the fusion products that are ejected into the SOL;
e- energy transferred to ions in plume expansion
• This reduces the exhaust velocity of the fusion products from 25,000 km/s to ~50 km/s and
increases thrust to >20 N
• Thrust/Isp is adjustable based on rate that gas is injected into the gas box
• The exhaust plume is directed by a magnetic nozzle, consisting of a throat coil and nozzle coils to
accelerate the flow.

7. 7
Princeton Field Reversed Configuration (PFRC)
8/4/15
! Field Reversed Configuration (FRC) is core of
DFD
- Simple geometry with fewer coils
! RF heating with odd-parity rotating magnetic
fields naturally limits reactor size
- Plasma radius in range 20-40 cm
- Size of 1-10 MW which is ideal for space
! Confinement with high temperature
superconducting coils
! Burns aneutronic D and 3He with beta greater
than 0.8
! Linear configuration allows for
configuration as a rocket engine
! Magnetic Nozzle
! Add H or D+ to augment thrust
! Variable exhaust velocity
! 50 to 20,000 km/s
! P = 0.5 TuE/η, with η ∼0.5
Gas Box
Exhaust Plume
SOL Heating Section
Field Shaping
Box
Separatrix
Closed Field
Nozzle Coil
Propellant
D-He3 Fusion
Coils
Coil
Fueling
RMFo
Antenna
Region
Shielding

8. 8
Steerable Magnetic Nozzle
8/4/15
! Plume needs to be steered for momentum
management
- 1-2 degrees of deflection needed
! Seek magnetic methods as alternative to mechanical
gimbals for entire engine
- Expensive and heavy
! Steering coils downstream of nozzle throat, or
perhaps a tiltable plate to direct the flow

9. 9
Heat Engine
8/4/15
! Brayton cycle shown
- Ericsson cycle would have multi-stage
compressors and turbines
! Helium working fluid
! Mass is sum of heat engine
components and radiators
- Brayton efficiency of 63% possible
- Ericsson 74%
! Generator
- 28 V DC Generators used on aircraft
" Should be the same voltage as
required by the RF generator

10. 8/4/15
Pluto Mission

11. 11
Mission Plan
8/4/15
! Direct insertion into interplanetary orbit by a Delta IV Heavy
or other launch vehicle
! 20 N thrust to change the velocity by 55 km/s
! Coast
! 20 N thrust to decelerate to intercept Pluto
! Spiral into polar Pluto orbit
! Map surface with altimeter
! Lander detaches and lands on surface
- Powered by laser from the orbiter
- Navigation uses maps generated during mapping phase
! Orbiter changes orbit as needed to survey the entire planet
! Possibly departs Pluto for the Kuiper belt

12. 12
Spacecraft
8/4/15
! Fits within Delta IV
Heavy fairing
! Within the mass
allowance for the Delta
IV
! Dual radiators
! Dual JPL Deep-Space
Optical Communication
System (DSOC) units
! Lander mounted on the
front

13. 13
Trajectory to Pluto
8/4/15
! July 2028 departure date
! Red line on second plot is the
Delta IV Heavy payload into
interplanetary orbit
! 4 year transfer shown below
- Blue circle is Earth orbits
! 110 km/sec Delta-V
! Nearly straight line
! No gravity assists

14. 14
GN&C
8/4/15
! Optical navigation used
throughout mission
- Developed under NASA SBIR
- Uses articulated camera
shown to the right and a new
sun radiance/chord sensor
! Attitude control uses RCS
system and DFD magnetic
nozzle steering

15. 15
GN&C
8/4/15

16. 16
Lander
8/4/15
! ECAPS 220 N engine
! 4 m2 solar panels for
orbital laser power
system
! Begins descent from 15
km
! Optimal guidance law
switches to combination
bang-bang/linear
controller for final
descent

17. 17
Laser Lander Power System
8/4/15
! Beam power by fiber laser
at 1080 nm
- Same as Navy LaWS
! Standard solar cells to
receive the power
- 30 kW transmitted power
- 0.4 m mirror
- 4 m2 solar cells on lander
- 2 DOF steerable array
! 31.9 Wh per pass
- Store in batteries
Princeton Satellite Systems
Power Per Pass = 31.9 Wh Wavelength 1080.0 nM
0 5 10 15 20 25
Power(kW/m
2
)
0
5
10
15
20
25
Time (min)
0 5 10 15 20 25
Distance(km)
0
500
1000
1500
2000
2500
3000

18. 18
High Power Communications with Earth
8/4/15
! JPL Deep Space Optical Communications System
(DSOC)
! Compatible with the laser power system
! 135 Mbps from Pluto with 30 kW

19. 19
Work Plan
8/4/15
! Ion heating experiment at
PPPL (DOE Funding)
! Magnetic nozzle research at
PPPL (DOE Funding)
- Magnetic nozzle steering
! Mission analysis for the Pluto
mission
- Optimize power, thrust and
exhaust velocity for different
launchers
- Optimize trajectory
- Science payloads
! Spacecraft design
- System design
- Detailed designs
" Fuel tanks
" DFD engine design
" Radiator system
" GN&C
" Communications
! Lander Design
- GN&C
- Propulsion
- Power
- Science payloads

20. 20
Conclusions
8/4/15
! The Pluto Orbital Mission would be a new class of
exploration missions
- Cannot be achieved with any other technology
! Would expand on the knowledge gained by the New
Horizons mission
! The propulsion and power system would be applicable to
a wide range of missions and applications
- Human missions to Mars
- Robotic missions to the gas giants
- Interstellar missions
- Space and terrestrial power generation

21. 21
For More Information
8/4/15
Stephanie Thomas
sjthomas@psatellite.com
Michael Paluszek
map@psatellite.com
Dr. Samuel Cohen
scohen@pppl.gov
Princeton Satellite Systems
6 Market St. Suite 926
Plainsboro, NJ 08536
(609) 275-9606
http://www.psatellite.com
21

22. 22
References
8/4/15
Papers/Conferences
! Y. Razin et al., A direct fusion drive for rocket propulsion, Acta Astronautica, Vol. 105, Issue 1, December
2014, pp. 145-155
! M. Paluszek et al, Direct Fusion Drive for a Human Mars Orbital Mission , 65th INTERNATIONAL
ASTRONAUTICAL CONGRESS, Sept. 29-Oct. 3, 2014
! Joseph B. Mueller et al, Direct Fusion Drive Rocket for Asteroid Deflection, 33rd International Electric
Propulsion Conference, October 6–10, 2013
! G. Pajer, Y. Razin, M. Paluszek, A. H. Glasser, S. Cohn, Modular Aneutronic Fusion Engine, Space
Propulsion 2012, May 2012
! Modular Aneutronic Fusion Engine for an Alpha Centauri Mission, M. Paluszek, S, Hurley, G. Pajer, S.
Thomas, J. Mueller, S. Cohen, D. Welch, DARPA 100 Year Starship Conference, September 2011.
Patents
! M. Buttolph, D. Stotler and S. Cohen, “Fueling Method for Small, Steady-State, Aneutronic FRC Fusion
Reactors,” 61/873,651, filed September 4, 2013
! M. Paluszek, E. Ham, S. Cohen and Y. Razin, “In Space Startup Method for Nuclear Fusion Rocket Engines,”
61/868,629, filed August 22, 2013.
! S. Cohen, G. Pajer, M. Paluszek and Y. Razin, “Method to Produce High Specific Impulse and Moderate Thrust
From a Fusion-Powered Rocket Engine,” PCT/US2013/40520, filed May 10, 2013.
! S. Cohen, G. Pajer, M. Paluszek and Y. Razin, “Method to Reduce Neutron Production in Small Clean Fusion
Reactors,” PCT/US13/33767, filed March 25, 2013.