Micro-satellite propulsion KOIZUMI Hiroyuki (小泉 宏之) Graduate School of Frontier Sciences, Department of Advanced Energy & Department of Aeronautics and Astronautics (基盤科学研究系 先端エネルギー工学専攻，工学系航空宇宙工学専攻兼担) Propulsion and Energy Systems; Dec 21st (2015) Huge cost

Compensation Failure is by money ant time never excused

No growth of Conservative technology and long-time and human design Small satellite

・Welcome, new service

・Quick technology cycle

・Quick human-resource development

Innovation Small satellite

Small satellites 100 – 500 kg

Microsatellites 10 – 100 kg

Nanosatellites 1 – 10 kg Cubesat Unit: 10 x 10 x 10 cm3 Small propulsion; Resource

Mass Typically 10 – 20% of the satellite mass

Typically If parallel to the mission: < 20% Power If dependent from the mission: < 80% Typical power generation： 1–3 W/kg （e.g 10 kg satellite → 10–30 W） Small propulsion; Resource

Don’t lose the merit of small sat.

Budget Typical budget for propulsion would be 10-20%

Law Strict limitation for High-pressure gas, explosives, toxic materials. ΔV LEO; 100km altitude change 60 m/s

LEO; 1 degree orbit inclination 130 m/s

LEO 300km, 1-year drag compensation （50kg, 50cm x 50cm, CD1.4） 50 m/s

GEO; NSSK (1year) 50 m/s

Lunar orbit from GTO 2000 m/s Small Chemical Propulsion

・Cold-gas thruster ・Gas-liquid equilibrium thruster ・mono- propulsion using hydrogen peroxide ・Micro-solid array ・Solid microthruster Cold-gas thruster Cold-gas thruster；Principle

Blow-down from a high pressure tank by gas and temperature

Heater

Resisto-jet thruster

M/kg Density Isp/s * mol-1 (24 MPa) Isp  CF c / g He 4 0.04 180 N2 28 0.28 80 Xe 131 2.74 31

Propulsion and Energy Systems; Dec 21st (2015) Cold-gas thruster

Merit The simplest Not for Demerit Low specific impulse high ΔV Large high-pressure system

Heritage Already used in micro-/nano- satellites

Propulsion and Energy Systems; Dec 21st (2015) 1) SSTL; Gas Propulsion System

Propellant: 500g Xe or 176g N2 Thrust: 20 – 50 mN Isp : 42 s Xe or 100 s N2 Total impulse: 380 Ns 50 kg S/C ΔV = 6.4 m/s

Dry mass: 6.7 kg Dimensions: 400 x 254 x 215 mm3 Propulsion and Energy Systems; Dec 21st (2015) Cold-gas thruster

For ΔV of ～100 m/s?

SSTL; Microsatellite Gas Propulsion System

Propellant: 12 kg Xe Thrust: 18 mN Isp : 48 s Total impulse: 5644 Ns 50 kg S/C ΔV = 110 m/s Dry mass: 7.3 kg

Propulsion and Energy Systems; Dec 21st (2015) Gas-liquid equilibrium thruster Gas-liquid equilibrium thruster

One of the gold-gas

Propellant storage in liquid phase Specific impulse is the same as cold-gas thruster

Merit No high pressure system →Reducing system volume

Needing a heater for vaporization Demerit Needing a gas/liquid separation device

Propulsion and Energy Systems; Dec 21st (2015) 1) Thruster for IKAROS

Propellant: 20 kg HFC-134a Dry mass: 約20 kg Thrust：400 mN Isp：40 s Total impulse: 7000 Ns

Molecular mass：102 g/mol Vapor pressure: 0.57 MPa Liquid density: 1225 kg/m3

Metal foam for the separation using surface tension and temperature gradient No high-pressure system Propulsion and Energy Systems; Dec 21st (2015) Mono-propellant thruster Hydrogen peroxide thruster

Hydrogen peroxide + catalyst →Isp: 80 s

Propellant feeding →Bladder + High-pressure gas Propellant tank×２＋Pressure tank ×１

Propulsion and Energy Systems; Dec 21st (2015) Thruster for Hodoyoshi-1/3

Thruster for Hodoyosh-3

Power 3.4W Mass 5.8kg, including 2 kg propellant Size 265×270×85 mm3 Thrust 350 mN

Isp >80 s ΔV 30m/s

Propulsion and Energy Systems; Dec 21st (2015) Hydrogen peroxide thruster

Merit High Isp as CP

Demerit Toxity of H2O2 Rejected for H2A secondary payload (UNIFORM1) Needing on-site charge

Heritage Hodoyoshi-1/3

Propulsion and Energy Systems; Dec 21st (2015) Solid-propellant thruster Micro-solid array

Digital control of micro-solid propellant MEMS fabrication Micro Electro Mechanical Systems using semiconductor device fabrication technologies

Propulsion and Energy Systems; Dec 21st (2015) マイクロソリッドアレイ

長所 Ultra miniaturization without gas system Easy fabrication of arrayed structure 短所 Small ΔV e.g. 30 μNs by 1shot

300 mNs by 100x100 array

ΔV = 0.3 m/s @ 1kg S/C

Propulsion and Energy Systems; Dec 21st (2015) Laser ignition, solid microthruster

Laser ignition of multiple pellets

Boron & potassium nitrate

Propulsion and Energy Systems; Dec 21st (2015) Laser ignition, solid microthruster

Merit Cubesat compatible 10 m/s class ΔV Demerit ΔV less than 100 m/s Needing rotating mechanism

Isp:150s, 60 shots, 300-cc ΔV : 30 m/s for a 3kg Cube-sat

Propulsion and Energy Systems; Dec 21st (2015) Small Electric Propulsion

・ ・ ・Arc-jet thruster ・ ・Electrospray ・Microwave engine ・Hollow cathode thruster Pulsed Plasma Thruster Pulsed plasma thruster

Pulsed discharge of capacitor energy Solid propellant (not explosive), passive feed Electromagnetic acceleration

Propulsion and Energy Systems; Dec 21st (2015) パルス型プラズマスラスタ；特徴

Merit Simple feeding mechanism High specific impulse（500-1000 s）

Demerit Geometric limitation of propellant and ΔV EMI (electro magnetic interference) Component life time of 1 billion shots Heritage Several verifications

Propulsion and Energy Systems; Dec 21st (2015) Thruster on EO-1

Spacecraft EO-1 by NASA Launch: 2000 Mass: 570 kg Propulsion Impulse bit: 0.86 mNs Isp：1370 s Power：70 W (1Hz) Total mass: 4.95 kg Propellant: 0.14 kg ←!! Total impulse: 460 Ns →ΔV = 0.81 m/s

Propulsion and Energy Systems; Dec 21st (2015) Concept by Univ. Surrey for 3U- Propulsion module: ¼U Pulsed power module: ¼U

Mass 0.34 kg Power 1.5 Volume 480 cm3 Isp 320 s Propellant 1.1 g ΔV for 4.5 kg 2.7 m/s

Propulsion and Energy Systems; Dec 21st (2015) PROITERES by OIT (大阪工大)

PROITERES Launch by PSLV (Indian ) in 2012 10 kg, 30x30x30 cm3, 10 W Coaxial pulse plasma thruster Electrothermal acceleration, no feeding system Wet mass: 2.0 kg (Head:0.3kg, Cap.:0.2kg PPU:1.0kg, Cables:0.5 kg) Total impulse: 5 Ns（ΔV 0.5 m/s）

Propulsion and Energy Systems; Dec 21st (2015) Pulsed plasma thruster; Summary

• Compatible from cubesat to 100 kg S/C • High technical maturity

• Few actual usages, so far • ΔV limitation • Electromagnetic interference

Propulsion and Energy Systems; Dec 21st (2015) Ion thruster Ion thruster

Electrostatic acceleration of ions

Inevitable electron emission Neutral Ion

Plasma source Ion acceleration Electron Propellant

Power

electron emission

Propulsion and Energy Systems; Dec 21st (2015) Ion acceleration

Example of the ion beam Outside Beam Inside trajectory Ion beam

Electrostatic potential

Appropriately-designed grids system converges the ion beam

Propulsion and Energy Systems; Dec 21st (2015) Types of the plasma generators

• Direct current (DC) electron discharge

• Radio frequency (RF) discharge

• Microwave discharge

Propulsion and Energy Systems; Dec 21st (2015) DC-discharge ion thruster

Gas injection magnetic field

Electron emission

30 V Anode

Propulsion and Energy Systems; Dec 21st (2015) RF-discharge ion thruster

RF coil

Gas injection ICP

Induced magnetic field Insulating body Induced current

Propulsion and Energy Systems; Dec 21st (2015) Microwave discharge ion thruster

Gas injection magnetic field

Microwave emission Coaxial cable Antenna or waveguide Electron cyclotron resonance

푓microwave = 푓cyclotoron Propulsion and Energy Systems; Dec 21st (2015) Ion thruster

Merit

High Isp (1000-3000 s) High ΔV mission Storage in a tank

Demerit High-pressure tank and feeding system Complicated = a number of parts

Heritage The most heritage in standard-size S/C Small ion thruster: Hodoyoshi-4, PROCYON

Propulsion and Energy Systems; Dec 21st (2015) μRIT by Univ. Giessen

The smallest thruster in RIT series RF plasma Developed for LISA

RIT for (four thruster heads) Dry mass: 14 kg Propellant: 0.4 kg Xe Thrust: 7 – 100 μN Power: 60-86 W (PCU: 26 W)

Max. thrust 600 μN

Propulsion and Energy Systems; Dec 21st (2015) Research by JPL & UCLA

DC-discharge, 30 mm of beam diameter Thrust：3.0 mN Specific impulse：1700 – 3200 s Ion production cost: 400 – 600 V/ion *not included the neutralizer

DC-discharge = two cathodes Inside for plasma Outside for neutralizer

Propulsion and Energy Systems; Dec 21st (2015) Research by KU (九州大学)

Microwave discharge (μ10’s neutralizer based plsma source) Thrust 790 μN Isp 4100 s Microwave power 8 W *not included the neutralizer Beam power 20 W システムには45W必要 (8/0.4 + 20/0.8)

Propulsion and Energy Systems; Dec 21st (2015) MIPS, flight model

MIPS Flight Model

Performance Mass: 8.1 kg (incl. 0.9 kg Xe) summary Volume: 39 x 26 x 15 cm3 Power: 27 W Thrust: 210 μN Isp: 740 s Delta V: 140 m/s (50 kg S/C)

Propulsion and Energy Systems; Dec 21st (2015) A small secondary payload of HAYABUSA-2 Earth Flyby observation of a small asteroid PROCYON needs

1. Wheel unloading by RCS Multiple thrusters

2. High ΔV for orbit transfer Electric propulsion

3. Trajectory correction maneuver Chemical propulsion

©Google MIPS Miniature Ion Propulsion System Controller

Control

Xenon-gas Gas system Ion thruster

Power supplies Microwave High voltages I-COUPS Ion thruster and COld-gas thruster Unified Propulsion System Controller

Cold-gas Control thrusters Xenon-gas Gas system Ion thruster

Power supplies Microwave High voltages Cold-gas thruster Thrust (single) 22 mN Specific impulse 24 s Number of thrusters 8 7 W Power consumption (2 thrusters)

Cold-gas thruster Thruster valve Sharing gas system is superior to increasing Isp

Xenon 2.57 kg Gas system1 (Tank) 2.01 kg Gas system

Cold-gas 4.5 kg !! thrusters 0.41 kg Gas system2 (others) Power supplies 2.25 kg 1.31 kg Controller Ion thruster 0.95 kg 0.38 kg

I-COUPS; ITU全運転(5分平均プロット ) 論文用 from Dec 28 (2014) to Mar 12 (2015); 運転判定条件:SPS-I (mA)>1.00

250

200 223 h

150

100

50

Total operating time/hours operating Total 0 Accumulated operation time/hours operation Accumulated The miniature propulsion system of PROCYON has operated for more than 6 months, as the first interplanetary micropropulsion.

COTS-based micro-EP subsystems, including the high-pressure gas system, have been in good health.

The cold-gas-thruster RCS are successfully working over 103 operations

The ion thruster operated in 223 hours.

©Hodoyoshi-3&4, The University of Tokyo Iodine ion thruster by Busek

Thrust 600 μN Specific impulse 2000 s Power 30 W System Dry Mass 1.7 kg Propellant Mass 1.5 kg

Lunar Ice Cube; launch in 2018

Propulsion and Energy Systems; Dec 21st (2015) 54 Ion thruster; summary

• Studies are increasing, but fewer than PPT

• Few thrusters completed as a system

• UT launched/operated the first one, and may be followed by Busek.

• Xenon limits the dry mass as >3 kg

• The highest ΔV potential

Propulsion and Energy Systems; Dec 21st (2015) Other Electric Propulsions Microwave engine

Developed in Hokkaid Univ. (北海道大学) μ10’s neutralizer based plasma source Electrostatic acceleration, no grids = Double discharge, cusped field Hall effect thruster

Endurance test Components development for Hokkaido satellite (no information update)

Propulsion and Energy Systems; Dec 21st (2015) Microwave engine

Including PPU eff.

18.5W

38.5W

57 W total power

T: 0.6 mN Isp: 1015 s

Propulsion and Energy Systems; Dec 21st (2015) Small arc-jet thruster

Micro-Multi-Plasma-jet Array

Small arrayed nozzle by laser etching Needing high pressure feeding system

Thrust 1.1 mN by 3x3 array Power < 10 W Isp 70 s (N2)

Propulsion and Energy Systems; Dec 21st (2015) Electrospray thruster

Emission of charged particles from liquid surface by strong electric field ～100 kV/mm MEMS, μm-needle → array No plasma → High efficiency

Isp depends on specific charge and mass liquid metal Oil Ionic liquid FEEP

10,000 s 100 s 1000 s

Propulsion and Energy Systems; Dec 21st (2015) FEEP: Field Emission Electrostatic Prop.

In-FEEP: using Indium LMIS (Liquid Metal Ion Source) is not a thruster but has a lot of space utilization heritage

9 LMIS Assembly Thrust：0.1 – 100 μN Isp: 5,800 s @ 25 μN Total Impulse: 6100 Ns Propellant: 15 g Indium

Ultra-accurate

Propulsion and Energy Systems; Dec 21st (2015) Vacuum-arc thruster

Surface discharge in vacuum Propellant: electrodes ＋ insulator (dielectric material) One type of the pulsed plasma thrusters （using a capacitor, but not using an ignitor） Merit/demerit is similar as PPT

Propulsion and Energy Systems; Dec 21st (2015) Hollow cathode thruster

Hollow cathode（electron source）as thruster Acceleration: electrothermal ＋ plasma potential Merit: already developed for space utilization Thrust 1.6 mN Power 55 W Isp 85 s PPU: 260 x 86 x 23 mm3

Needing high pressure Similar with resisto-jet

Propulsion and Energy Systems; Dec 21st (2015) Microthruster

Motivation of small sat: Easy, Quick, Cheep

Motivation of small prop.の魅力: same

Abundant researches for microthrusters （more than standard sized propulsion）

Few flight heritage

Propulsion and Energy Systems; Dec 21st (2015) Check points for microthrusters

Point 1: Don’t trust specific impulse Point 2: Total system mass & power

Point 3: Check the sub-components Specific impulse

Case 1) EP; Isp 3000s, Max Prop. 10 g, Dry M. 5 kg Case 2) CP; Isp 30s, Max Prop. 1000 g, Dry M. 4 kg Which is better? Both have the same wet mass, but Case 2 has shorter firing time

Total impulse is the most important

ITotal = Isp * g * MProp

Case 3) Isp 300 s, Max Prop. 1 kg, Dry M. 4 kg Quite attaractive Propulsion and Energy Systems; Dec 21st (2015) System mass and power

No thruster operate without sub-components System (total) mass and power are important

Thruster: 10g, Sub-component: 1 kg ??

Gas-feeding system has dominant mass Does it have a neutralizer?

Few direct drive by satellite bus voltage Needing PPU (high vol.，DC→AC, etc） High voltage supplies: 50-90% efficiency Mcirowave ：20-40% efficiency

Propulsion and Energy Systems; Dec 21st (2015) Sub-components e.g. ion thruster of HAYABUSA-1/2 Ion thruster by NEC (research by ISAS) Power and system assembling by NEC High-pressure system by MHI

Who is responsible for the microthruster?

Completeness of the subcomponents

Simple subcomponents are merits

Propulsion and Energy Systems; Dec 21st (2015) Summary

No standard microthrusters My perspective:

ΔV > 100 m/s → Ion thruster S/C of >20 kg ΔV < 100 m/s → Cold-gas thruster Pulsed plasma thruster ΔV > 10 m/s → No candidate S/C of <20 kg ΔV < 10 m/s → Pulsed plasma thruster Solid microthruster

Important: non high-pressure and non toxic

Propulsion and Energy Systems; Dec 21st (2015) Thank you