Electric Propulsion for Future Space Missions

Part I

Bryan Palaszewski

Digital Learning Network

NASA Glenn Research Center

at Lewis Field

Introduction

• Why electric propulsion?– Types– Applications

• Some history

• Future missions and vehicles

• A very cool future

Solar Electric Propulsion Module

Why High Exhaust VelocityIs Important

Ve Vs/c

CHEMICAL PROPULSION

ELECTRIC PROPULSIONROCKET EQUATION

Mfinal

Minitial= EXP

– ²V s/c

Ve

Isp =Ve

gc

PayloadPropellant

Power Supply

PayloadPropellant

Chemical

Electric

Energy Limited

Power Limited

Propellant Velocity

Total Impulse

Thrust

Time

Chemical

Chemical

Electric

Electric

Chemical & Electric Propulsion Have Intrinsic Differences

Solar and Nuclear Electric Propulsion Subsystems

Power Conditioning

Solar Cells

Thrust

Electric Thruster

PropellantExhaust

Sun

Thermal-to-Electric Power

Conversion

Nuclear Reactor

Electric PropulsionHistorical Overview

1903 -- K. E. Tsiolkovsky derived the “Tsiolkovsky” or “Rocket” Equation commonly used to show the benefits of electric propulsion

1906 -- R. Goddard wrote about the possibility of electric rockets

1911 -- K. E. Tsiolkovsky independently wrote about electric rockets

1929 -- World’s first electric thruster demonstrated by V. P. Glushko at the Gas Dynamics Laboratory in Lenningrad

1960 -- First “broad-beam” ion thruster operated in the U.S. at the NASA Lewis (now Glenn) Research Center

Electric PropulsionHistorical Overview

1964 -- First successful sub-orbital demonstration of an ion engine (SERT I) by the U.S.

1964 -- First use of an electric thruster on an interplanetary probe (Zond 2) by the USSR

1970 -- Long duration test of mercury ion thrusters in space (SERT II) by the U.S.

1972 -- First operation of a xenon stationary plasma thruster (SPT-50) in space (Meteor) by the USSR

1993 -- First use of hydrazine arcjets on a commercial communications satellite (Telstar 401) by the U.S.

The First Electric Thruster

• Developed by V. P Glushko at the Gas Dynamics Laboratory in Lenningrad, 1929 - 1933

• Solid and Liquid Conductors Were Vaporized by High Current Discharges in the Plenum Chamber and Expanded Through the Nozzle

• Power Provided by 40 kV, 4 mF Capacitors

Types Of Electric Thrusters

• Electrostatic– Ion– Hall

• Electrothermal– Arcjet– Resistojet

• Electromagnetic– Magneto plasma dynamic (MPD)– Many others

Types Of Electric Thrusters

THRUSTER POWER RANGE SPECIFIC IMPULSE (s)

Electrothermal 100s of watts 300 to 400

Resistojets

Arcjets

Hydrazine kilowatts 500 to 600

Hydrogen 10s of kilowatts 900 to 1200

Ammonia kilowatts to 10s of kilowatts 600 to 800

Electrostatic

Gridded Ion Engines watts to 100 kilowatts 2000 to 10,000

Stationary Plasma Thrusters (SPT) 100s of watts to 10’s of kilowatts 1000 to 2500

Thruster with Anode Layer (TAL) 100s of watts to 10’s of kilowatts 1000 to 4000

Electromagnetic

Magnetoplasmadynamic (MPD)

Pulsed kilowatts (average) 1000 to 4000

Steady-State 100s of kilowatts to megawatts 3000 to 7000

Pulsed Plasma Thruster 10s to 100s of watts (average) 1000 to 1500

Pulsed Inductive Thruster 10s of kilowatts 3000 to 5000

Electron Cyclotron Thruster kilowatts to 10s of kilowatts 2000 to 4000

Many Others

Ion Thruster

Ion Thruster

POSITIVE GRID (AT 1070 V)

NEGATIVE GRID (AT -200 V)

ANODE (AT +1100 V)PROPELLANT FEED

NEUTRALIZER KEEPER (AT +5 V)

MAGNET RINGS - ELECTRONS ARE REMOVED FROM THE DISCHARGE CHAMBER AT THE MAGNETIC FIELD CUSPS

NEUTRALIZER CATHODE (AT -15 V)

KEEPER ELECTRODE (AT +1075 V)

PROPELLANT FEED

MAGNETIC FIELD LINES (USED TO IMPROVE IONIZATION EFFICIENCY)

HOLLOW CATHODE (AT +1070 V) EMITS ELECTRONS INTO THE DISCHARGE CHAMBER

PROPELLANT FEED

IONS ACCELERATED ELECTROSTATICALLY THROUGH A NET VOLTAGE OF 1100 V

PLASMA BRIDGE

ION BEAM (AT THE AMBIENT SPACE

PLASMA POTENTIAL) ( 0 V )

ELECTRONS EMITTED BY AN EXTERNAL CATHODE ARE INJECTED INTO THE ION BEAM FOR NEUTRALIZATION

PLASMA (AT +1100 V)

ION PRODUCTION VOLUME

ELECTRONS IMPACT ATOMS TO CREATE IONS

Ion Thruster Layout

Hall Thruster

SPT-1001350 W

1600 lbf-s/lbm (Nominal)

SPT-70700 W

1450 lbf-s/lbm (Nominal)

SPT-1404000 W

1700 lbf-s/lbm (Nominal)

SPT-50300 W

1200 lbf-s/lbm (Nominal)

Thrusters designed and fabricated by the Design Bureau Fakel,

Kaliningrad (Baltic Region), Russia, and

offered by International Space

Technology, Inc.

Hall Thruster

Magnet Coils

Dielectric Walls

Cathode

Power SupplyPower SupplyXe

Xe

Anode

Ez

Br

Hydrazine Arcjet

Primex Aerospace Hydrazine Arcjet: 1.8 kW, 200 mN, 500 lbf-s/lbm

Arcjet Thruster

CATHODE

ANODE

CURRENT ARC

PROPELLANT IN

THRUSTER EXHAUST

Arcjet ThrusterShip Set of Four Olin Aerospace 500 lbf-s/lbm Hydrazine Arcjets

and Power Processing Unit

Magneto Plasma Dynamic (MPD) Thruster

Pulsed MPD Thruster Operating on Argon Propellant at Princeton University

Magneto Plasma Dynamic (MPD) Thruster

J x B Propellant

Insulator Backplate

B

J

Anode

Anode

Propellant

Cathode

Current Streamlines

Self-Induced Magnetic Field

PlasmaCL

Pulsed Plasma Thruster

Pulsed Plasma Thruster

Pulsed Plasma Thruster

NASA Glenn Electric Propulsion Laboratory (EPL)

NASA Glenn Electric Propulsion Laboratory (EPL) Contributions

• On September 23, 2001, the Deep Space 1 ion thruster set a record of 16,000 hrs. of operation while propelling the spacecraft on its encounter with Comet Borrelly.

• In preparation of MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) probe mission, VF-6 was used to characterize components under a 10-sun solar insolation environment.

• On December 3, 2000, hollow cathodes, which were developed at GRC and tested in VF-5 as part of the Plasma Contactor Unit, began protecting the International Space Station from harmful space plasma voltage potentials.

NASA Glenn Electric Propulsion Laboratory (EPL) Contributions

• A refractive secondary concentrator (RSC) achieved temperatures of 1455 Kelvin with an 87% throughput in VF-6.

• On January 4, 2002, a pulsed plasma thruster on Earth Observing 1 demonstrated a highly fuel efficient method of controlling spacecraft attitude and "pointability."

• Conducted first integrated solar dynamic system test from solar input to electrical power in VF-6.

Jupiter

Saturn

Uranus

Neptune

Neptune and Ion Thruster

Pluto

Deep Space 1

Deep Space 1 Thruster / Spacecraft Compatibility Testing

Deep Space 1 Thruster

• Launch of Deep Space 1

• Boeing Delta II (7326) Rocket

• October 24, 1998

DS-1 Trajectory

Autonomous Navigation

Comet Borrelly

Comet Borrelly