1. THE RESEARCH OF AEROBRAKE TECHNOLOGY USING ELECTRODYNAMIC TETHER
Master Thesis Presentation
THE RESEARCH OF AEROBRAKE TECHNOLOGY USING ELECTRODYNAMIC TETHER
Kazuhiko Yotsumoto
Space Systems Dynamics Laboratory
Department of Aeronautics and Astronautics

2. Contents Introduction Objective Background
EDT (Electro-Dynamic Tether)
Simulation
Simulation Models
Initial and Final Conditions in Simulation
Comparison Differences
Simulation Results
Conclusions

3. (Geostationary Transfer Orbit)
Objective
To verify the
Use of EDT
Aerobraking due to the Earth’s Atmosphere
from GTO to LEO around the Earth.
GTO
(Geostationary Transfer Orbit)
LEO
(Low Earth Orbit)

4. Background Tether and Aerobraking are Attractive Orbit Transfer Means
A 50-kg class Tether Satellite
named “QTEX” is developed in SSDL
Demonstrating this Concept around the Earth
QTEX (Kyushu University Tether Satellite Experiments), H-IIA Rocket

5. Principle of EDT Induced EMF ： Decelerating Force ： Earth
@Equatorial Plane
Induced EMF ：
Decelerating Force ：
EMF (Electro-Motive Force)

6. Tether Dynamics Tether Conditions Assumptions
Tether is rigid and straight
Tether has Mass
Assumptions
Point mass
Derivative of Moment of
Inertia is assumed Constant
Inclination is Constant
f : True Anomaly

7. Simulation Models 1 Target Satellite QTEX ： Summary of Configuration
Emitter
Field Emitter Array Cathode
Collector
Bare (Conductive) Tether

8. Simulation Models 2 Orbital Perturbation
Only Atmospheric Drag is considered
Atmospheric Density used Exponential Model
Plasma Model
Original Model based on Test Case of
International Reference Ionosphere 2001

9. Original Plasma Model
Test Case Results

10. Simulation Models 3 Magnetic Field Model
International Geomagnetic Reference Field 2005
Numerical Integration Method
Adams-Bashforth-Moulton Method
Procedure to obtain Solutions
“Prediction→Evaluation→Correction→Evaluation”

11. OML Current per unit Length
Simulation Models 4
Current Estimation Method
OML (Orbital-Motion Limited) Theory can be adopted if Debye Length (2.3mm) ＞ Tether Radius d/2 (1mm)
Tether e e
Debye Length
OML Current per unit Length

12. Initial and Final Conditions
Initial Conditions
At Perigee, is 0 [deg] and is 0 [deg/s]
Starting Date and Time is January 1, 2000, at 0:00 a.m.
Initial Attitude at Perigee is shown below
m : Mother Satellite
d : Daughter Satellite
: Loading Emitter
-90 < ψ [deg] < 90
Final Condition
QTEX Altitude reaches 80 [km]

13. Comparison Differences
Comparisons:
[A] Between EDT and NOT EDT Satellite
[B] Among various Tether Lengths
[C] Among various Tether Diameters
[D] Between “one-way current” Mode and
“two-way current” Mode

14. Comparison Differences
Assumed Tether Parameters
Assumed QTEX Weight
40kg
Constraints of H-IIA Rocket
≦ 50kg
Available Tether Weight
10kg

15. Due to only Atmospheric Drag
Simulation Results 1
[A] Between EDT and NOT EDT Satellite
EDT Satellite
NOT EDT Satellite
35920 [km] / 53.8 [hours]
750 [km] / 1 [year]
Due to only Atmospheric Drag
Around Apogee
“one-way”
750 [km]

16. Case 1 Results

17. Simulation Results 2 [B] Among different Tether Lengths
“one-way”
[B] Among different Tether Lengths
Case 1
Case 2
Longer Length is more effective
Induced Electromotive Force
Case 3
Decelerating Force

18. Simulation Results 3 [C] Among different Tether Diameters
“one-way”
[C] Among different Tether Diameters
Case 1
Case 4
Wider Diameter is more effective
OML Current
Case 7

19. Simulation Results 4 Fs : Drag
[D] Between “one-way current” Mode and “two-way current” Mode
“one-way”
“two-way”
Fs : Drag

20. Simulation Results 5 Fs : Drag
[D] Between “one-way current” Mode and “two-way current” Mode
“one-way”
“two-way”
Fs : Drag

21. (Geostationary Transfer Orbit)
Conclusions
Orbit Transfer using the
Electrodynamic Tether
Aerobraking due to the Earth’s Atmosphere
from GTO to LEO around the Earth is very effective.
Efficiency of EDT depends mainly on Angle
GTO
(Geostationary Transfer Orbit)
LEO
(Low Earth Orbit)

22. Thank you for your attention