Busek Electrospray Thrusters Aboard LISA Pathfinder

All-Electric CubeSat Propulsion Technologies

6th International Interplanetary CubeSat Workshop May 31st 2017

Dan Courtney Michael Tsay Nathaniel Demmons

Approved for public release; distribution is unlimited. Copyright May 2017.

HOW WELL WE DO IT … WHAT WE DO • Established the Domestic Hall Thruster Industry • Engines for Spacecraft • First US designed/built Hall thruster in space • Compact Power Electronics • First micro-pulsed plasma thruster in space • Space Environment Testing • First flight-demonstrated electrospray thrusters • Terrestrial R&D • First iodine fueled Hall thrusters & Ion engines

Largest Staff in the Industry devoted to Electric Propulsion

Five propulsion technologies; design, development, manufacture in-house ISO 9001:2008 and AS9100C certified Close cooperation with universities

Registered Manufacturer and Exporter with the US Dept. of State/DDTC

Approved for public release; distribution is unlimited. Copyright May 2017. 2 Missions: Past and Present

Approved for public release; distribution is unlimited. Copyright May 2017. 3 Busek CubeSat Propulsion Systems

BET-100: Mini Electrospray BIT-3: 3 cm Micro RF Ion • Passive feed • No internal cathode • No pressure vessel, valves • Tested up to 3,500s Isp BGT-X5 System: 1U/0.5N • Low Power • Iodine compatible Green Monoprop • High thrust (high acceleration) • High density Isp • Low-toxicity propellant BHT-200: 200W Hall Effect • Flight heritage • High thrust-to-power • Suitable for MicroSats BmP-220: Micro Pulsed Plasma • No moving parts, valves Compatible with >12U CubeSats • No pressure vessel • Teflon propellant • Low Power • System volume <1/3U Compatible with 3U or 6U CubeSats

Approved for public release; distribution is unlimited. Copyright May 2017. 4 Busek BIT-3 RF Ion Thruster

• Unprecedented performance per volume – Up to 2.9km/s deltaV for 6U/14kg CubeSat – >35kNs total impulse – 1.6U system envelope – 3.0kg wet, 1.5kg propellant loading – 0.66-1.24mN thrust and 1,400-2,640sec Isp (56-80W throttleable system input )

• 2-axis, ±10o gimbal integrated to thruster

• Volume efficient, conformal iodine tank – Lightweight, 22.5psig proof pressure Cathode • Rad-tolerant, miniaturized PPU – 28V regulated input, RS-485 comm – SOA, 90% efficiency RF power generators Thruster – “Rad-Hard Fence” providing 37MeV SEU immunity

• 80W power draw fits within capability of SOA solar arrays (120W for 6U)

Prototype BIT-3 Thruster Firing on I2

Approved for public release; distribution is unlimited. Copyright May 2017. 5 Busek BIT-3 RF Ion Thruster Performance

Adaption of Iodine Technology by Busek’s Mini RF Ion Thrusters (Engines) Latest BIT-3 System Performance (Calculated) • Iodine stored as a solid low pressure, high density propellant storage 1.4 y = 0.0242x - 0.6968 • The BIT series thrusters (1-7cm sized) are inherently iodine compatible 1.3 • The 3cm BIT-3 thruster is the world’s first gridded ion thruster using iodine 1.2 1.1 1.0 0.9 0.8

Thrust, Thrust, mN 0.7 0.6 0.5 0.4 56 58 60 62 64 66 68 70 72 74 76 78 80 Prototype BIT-3 Thruster Firing on Xe Prototype BIT-3 Thruster Firing on I2 Est. PPU Input Power within Throttleable Range, W

1.4 Xe I2 2800 1.3 y = 51.6700x - 1,487.1953 2600 1.2 2400 1.1 2200 1.0 2000

0.9 1800

Measured Measured Thrust, mN 0.8 1600 Total Total Isp, sec 0.7 1400 1200 0.6 28 30 32 34 36 38 40 42 44 46 48 50 52 1000 56 58 60 62 64 66 68 70 72 74 76 78 80 Measured Thruster Head Power (Not System Input Power), W Est. PPU Input Power within Throttleable Range, W Xe vs. I2 Thrust Comparison per Thruster Head Power

Approved for public release; distribution is unlimited. Copyright May 2017. 6 Busek BIT-3 RF Ion Thruster Mission Applications

BIT-3 System Enables New Mission Concepts via High ΔV

Two lunar missions, to be launched via NASA EM-1 (SLS, 2019) • Busek BIT-3 RF to achieve lunar capture and science orbits • 6U CubeSats

Lunar IceCube • Morehead State University Img: NASA, D. Folta • Detection of water / other volatiles from LLO

LunaH-Map • Arizona State University • Detection of hydrogen (water)

BIT-3 entering CDR for flight hardware deliveries end of CY17 6U/14kg Lunar IceCube in Stowed and Flight Configurations

Approved for public release; distribution is unlimited. Copyright May 2017. 7 Busek Electrospray Thrusters Aboard LISA Pathfinder

NASA/JPL Disturbance Reduction System Flown on ESA LISA Pathfinder mission • Technology demo for future gravity wave mission • Delivered 2008, launched 2015, • On-orbit success, >1500hrs/thruster 8 Busek systems in total

Null disturbances • Maintain spacecraft position to test masses Required to hold position <10 nm/Hz1/2

Other Missions • Comet ‘crumb’ detection Img: NASA/JPL • Full LISA mission Img: NASA/JPL

Approved for public release; distribution is unlimited. Copyright May 2017. 8 Busek’s BET-100 and BET-300-P Passive Thrusters

Compact / high performance Fully integrated, unpressurized propellant supply thrusters for CubeSats Low power, highly variable thrust BET-100

4.3cm

9.5cm Precision thrust control • <5 to 65μN @ 1μN resolution • Closed loop thrust control via PPU Highly scalable technology Compact 0.5U system • BET-300-P thruster head • Fully integrated propellant reservoir • Directly measured 300μN @ <6W • Unpressurized propellant tank • 50Ns+ total impulse Modular/distributable form factor

Low power, <6W max. system power In active development • Presently at TRL 3 Under development • Qual. Testing Q2 2017 • Flight in 2018 on 6U AMES Pathfinder

Approved for public release; distribution is unlimited. Copyright May 2017. 9 Electrospray Thrusters as a Precision CubeSat RCS

Small Form Factor Retains LISA-Proven High Precision

e.g. 6U S/C

Passive Electrospray Thrusters as Precision RCS • 100’s of nN resolution; 10’s of nNm torque on CubeSats

• Stable output, no sources of mechanical vibration

• Highly throttleable • Precision low thrust maneuvers and fast slews • Slew a 6U S/C through 180o in minutes

• Numerous applications: Compare with reaction wheels • Pointing for observations, laser comms… ~0.5uNm resolution • Formation flights, disturbance reduction Mech. jitter > 10mNm

Approved for public release; distribution is unlimited. Copyright May 2017. 10 Applications to CubeSat Attitude Control : Example Mission Scenario

6U CubeSat observatory tasked with taking long exposure inertial-stare images • Precision ACS via electrospray holds target centroid to sub-arcsec (w/appropriate feedback sensor) over 10’s of seconds • Same ACS used to slew to next image position Images 100/day Impulse /image 1.7mNs/img

Impulse /year 125Ns/yr

Margin 100% Total impulse 250Ns/yr

Mprop @ 1650s Isp 15g/yr

Mprop @ 65s Isp 400g/yr (e.g. cold-gas)

High Isp, highly throttleable electrosprays could serve as sole ACS

Approved for public release; distribution is unlimited. Copyright May 2017. 11 Applications to Small Spacecraft Trajectory Control: Formation Flight

Precision Formation Flight • Maintain static or dynamic separation in LEO or beyond earth • Offset environmental disturbances

Circular relative motion example

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BIT-3 system • Advancing towards TRL-6 in 2017 • High impulse density ~20kNs/U • Thrust up to 1.24mN • Iodine propellant • Compact, low pressure tanks • Scheduled for two 6U lunar missions launched via EM-1 Busek Electrospray Thrusters • Unique precision trajectory and attitude control capabilities • Extremely quiescent, no moving parts • Applications to precision pointing, formation flight, disturbance compensation… • BET-100uN • Highly throttleable precision thrust from <5 to 65μN • Fully integrated, unpressurized propellant supply • Advanced PPU with thrust control • Scheduled for flight on NASA Ames Pathfinder Tech. Demonstrator, 2018 • Upcoming developments • Scaled up thrust up to 300μN demonstrated • Compact, multi-axis system architecture

Approved for public release; distribution is unlimited. Copyright May 2017. 13 Facilities

Approved for public release; distribution is unlimited. Copyright May 2017. 14 Thruster Space Qualification and Simulation Chambers

T4 T6

T6 T8 T9 T8 T18

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DesignationDesignationArea (SF) Area (SF) Image Image CertificationCertification Function/MajorFunction/Major Equipment Equipment Used for assemblyUsed for of assemblyelectrosprays/flight of electrosprays/flight HW. Contains HW. an Contains an ISO-5 laminarISO-5 flow laminar hood for flow enhanced hood for cleanliness enhanced cleanliness operations'. operations'. Propellant drying Propellant station, drying various station, special various tools, special tools, CR-1 CR-1 ISO-8 ISO-8 200 200 microfluidic microfluidicdiagnostics. diagnostics.Nikon SMZ-10 Nikon stereoscopic SMZ-10 stereoscopic MicrofluidicsMicrofluidics (Class 100,000)(Classmicroscope 100,000) withmicroscope fiber-optic with illumination, fiber-optic illumination, Olympus BH2 Olympus BH2 binocular microscopebinocular withmicroscope video output, with video GR-202 output, laboratory GR-202 laboratory balance, 0.0001gbalance, resolution 0.0001g and resolution 104X ultrasonic and 104X cleaner ultrasonic cleaner

CR-2 CR-2 Used for incomingUsed for parts incoming inspection parts w/ inspection CMM & optical w/ CMM 3D & optical 3D Metrology Metrology ISO-8 microscope. ISO-8 microscope. Assembly, calibration, Assembly, testingcalibration, of micro-valves. testing of micro-valves. 300 300 Welding Welding (Class 100,000)(ClassContains 100,000) orbitalContains & laser orbital welder, & laser inductive welder, brazing inductive unit, brazing unit, Specialty OperationsSpecialty Operations optical particleoptical counter, particle and counter, xenon loading and xenon cart loading cart

Used for assembly,Used for integration assembly, andintegration testing ofand major testing flight of major flight CR-3 CR-3 HW. ContainsHW. electronic Contains GSE, electronic instrumentation, GSE, instrumentation, test test ISO-8 ISO-8 Assembly Assembly 1,000 1,000 benches, overheadbenches, gantry. overhead 100 SF gantry. parts 100cleaning SF parts annex cleaning annex (Class 100,000)(Class 100,000) Integration &Integration Test & Test accessible fromaccessible within fromCR3, automatedwithin CR3, 3-axis automated transition 3-axis 3- transition 3- axis magneticaxis probe magnetic probe

Approved for public release; distribution is unlimited. Copyright May 2017. 16 Selected Customers

Busek is proud to serve a variety of academic, government and commercial customers in the U.S. and abroad.