1

Pluto Orbiter Mission Direct Fusion Drive

Stephanie Thomas, PSS Michael Paluszek, PSS

Dr. Samuel Cohen, PPPL

2015

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

8/4/15

DFD Reactor Design

KEi

Nozzle

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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 pulse80 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 pulse10 kG field

i-temp = 5 keV

16 cm

2015-2019

$20M

Fuel H H D-3HeH

5

DFD Components

8/4/15

Heat Engine

Shielding

Radiator

Plasma

RFGenerator

SynchBremssn

Spacecraft Power Bus

Radiator

HTS Coil Blanket

CoilRefrigerator

SpaceRF

GeneratorHelium Coolant

Magnetic Nozzle

Auxiliary Power UnitD

3He

O2Electrolysis

D2O

Power Recycling

Restart

Gas Box

3He Injector

D Injector

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.

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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

BoxSeparatrix

Closed FieldNozzle Coil

PropellantD-He3 Fusion

Coils

Coil

Fueling

RMFo Antenna

Region

Shielding

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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

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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

8/4/15

Pluto Mission

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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

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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

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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

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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

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GN&C

8/4/15

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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

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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

Pow

er (k

W/m

2 )

0

5

10

15

20

25

Time (min)0 5 10 15 20 25

Dis

tanc

e (k

m)

0

500

1000

1500

2000

2500

3000

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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

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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

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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

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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

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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.