LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
Low Thrust Transfer to Sun-Earth L1 and L2 Points
with a Constraint on the Thrust Direction
Alexander A. Sukhanov
Natan A. Eismont
Space Research Institute (IKI)
of Russian Academy of Sciences
Moscow, Russia
LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
An experimental low-thrust mission to the Sun-Earth L1 and L2 points is
considered (Module-M mission)
MISSION GOALS
• Solar wind exploration
• Magnetic storm prediction
• Testing new technologies
MISSION STEPS
• Delivery of the spacecraft component to the International Space
Station (ISS) by Progress cargo spaceship
• Assembling the spacecraft at ISS
• Launch from ISS and transfer to L1 using Solar Electric Propulsion
• Transfer to the L1 point and insertion into a halo orbit
• Launch from the halo orbit, transfer to L2 point, and insertion into a
halo orbit
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SPACECRAFT CONCEPT
• Spacecraft is spin-stabilized with spin axis orthogonal to the Sun
• Solar arrays form a cylindrical surface coaxial to the spin axis
• Thrusters are directed along the spin axis in both directions
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
THRUSTER PARAMETERS
Name
Type
Power
Specific impulse
Efficiency (including loss in PPU)
Thrust force
Mass flow rate
Resource
Propellant
D-38
TAL
750 W
2200 s
0.5
0.035 N
1.6⋅ 10-6 kg/s
3000 hours
xenon
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SPACECRAFT PARAMETERS
Wet initial mass
290 kg
Xenon mass
85 kg
Characteristic velocity
7.5 km/s
Solar panel area
110 m2
Effective solar array area
30 m2
Electric power
3 kW
Number of thrusters
8
Number of simultaneously running thrusters
2
Maximum time of the low thrust run
7340 hr
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SPIRAL TRANSFER
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
ORBIT SHADOWING
• Launch in June-July or December-January minimizes the orbit
shadowing down to 7.5 percent of the spiral transfer time
• These optimal launch dates lead to a high (> 50°) inclination to the
ecliptic plane
• Launch in May or November was selected for the further analysis:
the shadowing is 8.5 percent, inclination to the ecliptic plane is 35°
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
PARAMETERS OF THE SPIRAL TRANSFER
Time of flight
280 days
Number of orbits
1330
Consumed characteristic velocity
6850 m/s
Propellant consumption
78.9 kg
Spacecraft mass
211.1 kg
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
TRANSFER TO L1 AND INSERTION INTO A HALO ORBIT
Time of flight (after the spiral)
140 days
Characteristic velocity of the insertion into halo
290 m/s
Propellant consumption
2.8 kg
Spacecraft mass in halo
208.3 kg
62,000 km
Amplitude Ay of the halo orbit
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH ZERO COMPLETE ORBITS
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH ZERO COMPLETE ORBITS
Consumed characteristic velocity
306 m/s
∆v1
50 m/s
196 m/s
∆v2
60 m/s
∆v3
Time between ∆v1 and ∆v2
70 days
The transfer duration
181 days
Propellant consumption
2.9 kg
Final spacecraft mass
205.4 kg
800,000 km
Ay amplitude of the L2 halo
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH ONE COMPLETE ORBIT
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH ONE COMPLETE ORBIT
Consumed characteristic velocity
224 m/s
∆v1
65 m/s
18 m/s
∆v2
141 m/s
∆v3
Time between ∆v1 and ∆v2
82 days
The transfer duration
259 days
Propellant consumption
2.2 kg
Final spacecraft mass
206.1 kg
300,000 km
Ay amplitude of the L2 halo
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH TWO COMPLETE ORBITS
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
L1 TO L2 TRANSFER WITH TWO COMPLETE ORBITS
Consumed characteristic velocity
70 m/s
∆v1
35 m/s
2 m/s
∆v2
33 m/s
∆v3
Time between ∆v1 and ∆v2
70 days
The transfer duration
319 days
Propellant consumption
0.7 kg
Final spacecraft mass
207.6 kg
150,000 km
Ay amplitude of the L2 halo
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SYMMETRIC TWO-IMPULSE L1 TO L2 TRANSFER
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SYMMETRIC TWO-IMPULSE L1 TO L2 TRANSFER
Consumed characteristic velocity
86 m/s
∆v1
43 m/s
43 m/s
∆v2
The transfer duration
307 days
Propellant consumption
0.8 kg
Final spacecraft mass
207.5 kg
62,000 km
Ay amplitude of the L2 halo
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
SUMMARY OF THE TRANSFERS
Flight time,
months
Total ∆v,
km/s
Total xenon
consumption,
kg
S/C mass,
kg
0
0
0
290
Acceleration in the spiral orbit
9.3
6.85
78.9
211.1
Transfer to and insertion in L1 halo
14.0
7.14
81.7
208.3
Transfer to and insertion in L2 halo
20 – 24.5
7.21 – 7.45
82.4 – 84.6
205.4 – 207.6
Rest for the correction maneuvers
–
0.05 – 0.29
0.4 – 2.6
–
Operation
Launch
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LIBRATION POINT ORBITS AND APPLICATIONS
Parador d'Aiguablava, Girona, Spain
10 – 14 June, 2002
CONCLUSIONS
• The low thrust orthogonal to the Sun allows performing:
– transfer to L1 or L2 Sun-Earth point;
– insertion into a halo orbit;
– halo-to-halo transfer.
This makes it possible to simplify the spacecraft design and
control
• Duration of both the Earth-to-halo and halo-to-halo transfers
can be shortened by means of a higher propellant consumption
• Propellant consumption can be reduced by means of the
duration increase for both the Earth-to-halo and halo-to-halo
transfers
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