Analysis of Electric Propulsion Systems for DragCompensation of Small Satellites in

Low Earth OrbitsThe Universtiy of Manchester

Teodor Bozhanov, ID: 9023890Supervisor: Dr. Peter C.E. Roberts

Final Report

02 May 2017

Abstract

Small satellites, in particular CubeSats, have been the study focus of many major

space agencies, universities and private organisations. Recent studies have shown

that small satellites can reach up to 95% of the operational capabilities of large

satellites, for only 5% of the cost.

One drawback however, is that CubeSats have no onboard propulsion system and

therefore no orbit maintenance and manoeuvre capabilities. This, coupled with the

fact that they are usually inserted at very low Earth orbits (VLEO (under 400 km)),

means that orbital lifetime is extremely limited. Consequently, small satellites and

CubeSats have reduced lifetime and operational capabilities, limiting the range of

their missions.

Electric propulsion systems can generate the required thrust for drag compensation,

while being extremely efficient. This results in a relatively low propellant fraction,

reducing the negative impact on the available payload.

This study focuses on using various Electric Propulsion (EP) and Atmosphere Breath-

ing Electric Propulsion (ABEP) systems to increase the lifetime and usefulness of

the satellites.

The scope of the study is limited to VLEO ranging from 100 to 300 km. This zone is

ideal for Earth observation and reconnaissance missions. In addition, it falls within

the range of the ABEP system, where higher atmospheric density is more favourable.

The computer model generated for this study accounts for 6 different types of per-

turbations and is able to model the change of orbital parameters with high degree

of accuracy. Preliminary results from several different types of EP show an increase

of orbital lifetime between 200 and 600%. In some cases the associated velocity

change is sufficient for performing small orbital transfers, rendezvous and docking

manoeuvres. Orbit raising of about 900 - 1200 km was observed from a couple of

thrusters.

It was seen that a trade-off zone, between EP and ABEP, starts to form from about

250 km below, where ABEP thrusters become more effective.

1

Contents

1 Introduction 9

1.1 History of Electric Propulsion . . . . . . . . . . . . . . . . . . . . . . 9

1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.3 Aims and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.4 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2 Physical Background 17

2.1 Space Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.1.1 Atmosphere and Vacuum Environment . . . . . . . . . . . . . 17

2.1.2 Neutral Environment . . . . . . . . . . . . . . . . . . . . . . . 19

2.2 Electric Propulsion Systems . . . . . . . . . . . . . . . . . . . . . . . 20

2.2.1 Electrothermal Acceleration . . . . . . . . . . . . . . . . . . . 21

2.2.2 Electrostatic Acceleration . . . . . . . . . . . . . . . . . . . . 23

2.2.3 Electromagnetic Acceleration . . . . . . . . . . . . . . . . . . 24

2.3 Atmosphere Breathing Electric Propulsion . . . . . . . . . . . . . . . 25

3 Literature Review 27

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.2 Relevant Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.2.1 Electric Propulsion . . . . . . . . . . . . . . . . . . . . . . . . 27

3.2.2 Atmosphere Breathing Electric Propulsion (ABEP) . . . . . . 30

3.2.3 Drag and Atmosphere Models . . . . . . . . . . . . . . . . . . 33

3.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4 Methodology 37

4.1 Mission Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.3 Assumptions and Limitations . . . . . . . . . . . . . . . . . . . . . . 38

5 Preliminary Analysis 41

5.1 Atmosphere Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.1.1 Drag Variation With Altitude . . . . . . . . . . . . . . . . . . 43

2

CONTENTS Teodor Bozhanov

5.1.2 Drag Variation With Latitude and Longitude . . . . . . . . . 43

5.1.3 Drag Variation With Solar Activity . . . . . . . . . . . . . . . 46

5.2 Orbital Propagators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.2.1 Energy Methods . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.2.2 Gausss Planetary Equations (GPE) . . . . . . . . . . . . . . 50

5.3 EP Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

5.3.1 Pulsed Plasma Thrusters . . . . . . . . . . . . . . . . . . . . . 53

5.3.2 Ion Thrusters . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

5.3.3 Field Emission Electric Propulsion . . . . . . . . . . . . . . . 56

5.4 ABEP systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

5.4.1 Intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

5.4.2 Thrusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

6 Results and Discussion 62

6.1 Drag Compensation With EP . . . . . . . . . . . . . . . . . . . . . . 62

6.1.1 ARC PPT Thruster . . . . . . . . . . . . . . . . . . . . . . . 64

6.1.2 RIT Ion Thruster . . . . . . . . . . . . . . . . . . . . . . . . . 65

6.1.3 IFM Nano FEEP Thruster . . . . . . . . . . . . . . . . . . . . 67

6.1.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

6.2 Drag Compensation With ABEP . . . . . . . . . . . . . . . . . . . . 74

6.2.1 Theoretical Predictions . . . . . . . . . . . . . . . . . . . . . . 74

6.2.2 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . 77

6.3 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7 Conclusion 81

8 Project Management 83

8.1 Semester I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.2 Semester II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

3

List of Figures

1.1 Number of Commercial Satellites with on-board EP system (Hoskins,

W.A. et al. 2013). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.2 Small satellites trends (2016-2022) (Doncaster and Shulman 2016). . . 14

1.3 Space Debris Population at different altitudes. Active Debris Re-

moval (ADR05) of 5 objects per year needs to be conducted to main-

tain current debris density (Liou, Johnson, and Hill 2010). . . . . . . 15

2.1 Variation of atmospheric layers with altitude (km) (Tewari 2007) . . . 18

2.2 Single particle momentum transfer. (Tribble 1995) . . . . . . . . . . . 19

2.3 Oxidised silver which is flaked off, exposing the underlying fresh ma-

terial which is oxidised again (Rooij 2010). . . . . . . . . . . . . . . . 20

2.4 1D Schematic of an Electrothermal Thruster (Jahn 2006) . . . . . . . 22

2.5 1D Schematic of Electrostatic Acceleration (Sforza 2016) . . . . . . . 23

2.6 Schematic of MPD accelerator (Sforza 2016) . . . . . . . . . . . . . . 24

2.7 Schematic of a typical PPT (Sforza 2016) . . . . . . . . . . . . . . . . 25

2.8 Atmosphere Breathing Ion Engine (Nishiyama 2003) . . . . . . . . . 26

3.1 Two Air Intake concepts: Funnel Concept a); Bypass Concept b). . . 31

3.2 Variation of the different atmospheric constituents with altitude (Schon-

herr et al. 2015) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3.3 Variation of Relative Density with Solar Activity (Tribble 1995) . . . 34

4.1 Analysis of Electric Propulsion Systems: Flowchart . . . . . . . . . . 39

5.1 Variation of Density With Altitude for 5 Different Atmosphere Models 42

5.2 Variation of Drag Force With Altitude for NRLMSISE and MSIS. . . 43

5.3 Drag Variation With Latitude, at Constant Longitude and Solar Flux,

for Every Hour at 300 km Altitude. . . . . . . . . . . . . . . . . . . . 44

5.4 Drag Variation With Longitude, at Constant Latitude and Solar Flux,

for Every Hour at 300 km Altitude. . . . . . . . . . . . . . . . . . . . 45

5.5 Maximum Drag Variation With Solar Flux, at Constant Longitude,

Latitude and Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4

LIST OF FIGURES Teodor Bozhanov

5.6 Solar Flux Drag Variation at 116 km altitude. . . . . . . . . . . . . . 47

5.7 Orbital Decay for 1U, 2 kg CubeSat . . . . . . . . . . . . . . . . . . . 49

5.8 Orbital Decay for 1U, 2 kg CubeSat using GPE . . . . . . . . . . . . 51

5.9 Orbital Decay for 1U, 2 kg CubeSat Using Extended GPE . . . . . . 52

5.10 Extended GPE Propagator: Orbital Decay of a 1U Cubesat (different

mission types) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

5.11 NASA S-iEPS thruster: tank configuration (left) and thruster circuit

arrangement (Krejci, Mier-Hicks, et al. 2015). . . . . . . . . . . . . . 55

5.12 IFM Nano Thruster Family (Reissner et al. 2015). . . . . . . . . . . . 56

5.13 BUSEK long annular intake (Hohman 2012). . . . . . . . . . . . . . . 58

5.14 JAXA long annular bypass intake with a conical diffusion region (Fu-

jita 2004). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

5.15 DSMC analysis with i