Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Mission Analysis andPerformance Comparison for an
Advanced Solar Photon Thruster
Bernd Dachwald1 and Patrick Wurm2
1Faculty of Aerospace Engineering,FH Aachen University of Applied Sciences, Germany
2Institute of Aeronautics and Astronautics,RWTH Aachen University, Germany
2nd International Symposium on Solar Sailing, New York City2022 July 2010
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 1 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
The Flat Solar Sail
The most extensively discussed solar saildesign concept is the flat solar sail (FSS)
Force acting on the ideal FSS:
FFSS = 2P(r)(A cos) cos n
Flat solar sail is used for light-collection and
thrust-direction Coupling betweenattitude and orbit control:
Effective light-collecting sail area A cosdecreases as the sail pitch angle increases
Changes of thrust direction require rotationof the whole solar sail structure (verydemanding for the attitude control systemdue to the sails huge moment of inertia andthe flexibility of its structure)
Ground deployment test of20 m 20 m solar sail atDLR/ESA in 1999 (imagecourtesy DLR)
Ground deployment test of20 m 20 m solar sail at NASAin 2005 (image courtesy NASA)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 2 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
The Simple Solar Photon Thruster
Alternative solar sail design concept is the compound solar sail orSolar Photon Thruster (SPT)
The SPT decouples light-collection and thrust-direction by usingtwo or three mirror elements
The Simple Solar Photon Thruster (SSPT) has two mirror elements(Collector and Director)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 3 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
The Solar Photon Thruster
The Dual Reflector Solar Photon Thruster (DR SPT) has threemirror elements (Collector, Reflector, and Director)
Force acting on the ideal SPT
FSPT = 2P(r)AC cos n
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 4 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Advantages of the Solar Photon Thruster
To maximize the change of orbital energy, it is usually desirable tohave a large transversal thrust component (perpendicular to theSun-spacecraft direction)
FSS: FFSS,t = 2P(r)(A cos) cos sin
SPT: FSPT ,t = 2P(r)AC cos sin
Norm
alize
d tra
nsve
rsal
thru
st
0
0.1
0.2
0.3
0.4
0.5
Difference
0
0.1
0.2
0.3
0.4
0.5
Pitch angle [deg]0 20 40 60 80
Normalized transversal thrust FSSNormalized transversal thrust SPTDifference
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 5 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Problems of the Solar Photon Thruster
According to previous theoretical studies, the SPT may excel theperformance of a flat solar sail . . . but . . . the previous investigated SPTmodels have several intrinsic oversimplification problems that can notbe disregarded for a thorough performance comparison with the flatsolar sail
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 6 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
The ASPT (Advanced Solar Photon Thruster)
We have developed a new Advanced Solar Photon Thruster(ASPT) design concept that avoids the problems of the SSPT andthe DR SPT
We have set the following requirements for the ASPT design:
1 Multiple reflections should be avoided2 The thermo-optical properties of the sail surfaces should be
considered3 Both the Collector and the Reflector are parabolic surfaces4 To avoid undesired torques, the ASPTs center of mass should
coincide with the Directors center of surface5 The finite size of the Director should be considered6 Shadowing effects should be considered
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 7 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
The ASPT (Advanced Solar Photon Thruster)
Director is located behind the Collector Collector must have a centerclearance
Payload (S/C bus) is located behind the Director ASPTs center of masscoincides with the Directors center of surface no unwanted torquesTo avoid that the Director can reflect some light rays onto the back side ofthe Collector, there is a minimum pitch angle min
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 8 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
ASPT SRP Force Model
The thermo-optical properties are described by the parametersP = {, s, f , b, Bf , Bb}Force acting on the ASPT comprises the force acting on theCollector, the force acting on the Reflector, and the force acting onthe Director
FASPT = FC + FR + FD (1)
Each force component was calculated with the method developed byL. Rios-Reyes and D. L. Scheeres (L. Rios-Reyes and D. L. Scheeres:Generalized Model for Solar Sails. Journal of Spacecraft and Rockets,42(1):182-185, 2005)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 9 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Force on the Collector
Force on the Collector:
FC = 2P(r)piR2C
[2a1,C
1
ln
(4 +
4 +
)+
+ 2a2,C1
(4 +
4 +
)+
a3,C2
(1 )]
r
P(r) : solar radiation pressure at distance r from the sunRC : radius of the Collector
RR : radius of the Reflector , radius of the Collectors center clearing : inverse of the light concentration ratio, =
(fRfC
)2=(RRRC
)2=
ARAC
fC : focal distance of the CollectorfR : focal distance of the Reflector
AC : effective Collector area, AC = piR2C
AR : effective Reflector area, AR = piR2R
: measure for design compactness, =(RCfC
)2=(RRfR
)2ai,C : derived thermo-optical properties of the Collector (i {1, 2, 3})
PC = {C , sC , f ,C , b,C , Bf ,C , Bb,C} {a1,C , a2,C , a3,C}r : Sun-spacecraft unit vector
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 10 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Force on the Reflector
Force on the Reflector:
FR = 2P(r)piR2C[a1,Ca1,R
1
ln
(4 +
4 +
)+
+ a1,Ca2,R1
(4 +
4 +
)+
a1,Ca3,R4
(1 )]
r
P(r) : solar radiation pressure at distance r from the sunRC : radius of the Collector : inverse of the light concentration ratio : measure for design compactnessai,j : derived thermo-optical properties (i {1, 2, 3}, j {Collector, Reflector})r : Sun-spacecraft unit vector
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 11 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Force on the Director
Force on the Director:
FD = 2P(r)AD,i
[a1,Ca1,R
8
((a1,D cos + a2,D)n + a3,D r
)]
P(r) : solar radiation pressure at distance r from the sunAD,i : effective light collecting area of the Director : inverse of the light concentration ratioai,j : derived thermo-optical properties (i {1, 2, 3}, j {Collector, Reflector, Director}) : Director pitch anglen : Sail normal (unit) vectorr : Sun-spacecraft unit vector
For the computation of AD,i , three different cases have to be considered(see paper).
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 12 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
ASPT Engineering Challenges
Although the light isnot concentrated inone single point onthe Reflector surface(as for the SSPT),the Reflector and theDirector are exposedto an enormousradiation flux
0.5
0.5
1
1
1
1.5
1.5
1.5
1.5
2
2
2
2.5
2.5
2.5
33
3.53.5
4
RC/R
R = f
C/f
R = 1/1/2
r [AU]
5 10 15 20 25 300.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
0.5
1
1.5
2
2.5
3
3.5
4 [TeU]
= 4
Radiator temperature as a function of lightconcentration and solar distance
1 TeU , 933 K: Melting temperature of aluminum
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 13 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
ASPT Engineering Challenges
To avoid the destruction of the Reflector sail film, its temperaturemust remain much below 1 TeU
At 1 AU solar distance, a light concentration ratio as small as 11.2results in T > 0.5 TeU for = 4
For the Reflector of an ASPT with a reasonable light concentrationratio, these results show that the commonly projected sail filmmaterials can not be used without having an active cooling system ormuch better reflective properties
In any case, demanding thermal and/or structural requirements forthe Reflector and Director mirror elements (that we have consideredby a (moderate) mass penalty)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 14 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
ASPT Parameters and Mass Calculation
We have used a complex model to calculate the ASPT mass for agiven characteristic acceleration (see paper)
The ASPT launch mass for a given characteristic acceleration isobtained from the solution of a constrained non-linear optimizationproblem
We have used the following input parameters (see paper):
Parameter Dimension FSS ASPTmin [deg] 0 35max [deg] 90 55SA [g/m
2] 22.7 22.7 - 0.05R [g/m
2] - 80D [g/m
2] - 80CB [g/m] - 150mPL [kg] 75 75min - 1/400RR,max [m] - 2.285Optical model real variableac [mm/s2] variable variable
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 15 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Comparison of the Solar Sail Launch Masses
Laun
ch m
ass [
kg]
100
120
140
160
180
200
220
240
260
Characteristic acceleration [mm/s2]0.1 0.12 0.14 0.16 0.18 0.2
real FSSOCIRID ASPTOCORID ASPTOCOROD ASPT
Optical models: OCIRID stands for a (real) optical Collector, an idealReflector, and an ideal Director (. . . and so on)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 16 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-Venus Rendezvous:Mission Description
The solar sails are launched from Earth onto an interplanetarytrajectory with zero hyperbolic excess energy (C3 = 0)
The solar sails have to spiral towards the Sun
Orbit-to-orbit rendezvous (to obtain the constellation-independentabsolute flight time minimum)
Final constraints for successful rendezvous:
Distance to Venus 6.0 105 km (< mean SOI)Relative velocity to Venus 0.5 km/s
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 17 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-Venus Rendezvous:Results
Flight time overcharacteristicacceleration Flig
ht ti
me
[day
s]
400
600
800
1000
1200
1400
Characteristic acceleration [mm/s2]0.1 0.12 0.14 0.16 0.18 0.2
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 74.7 - 78.3 %OCORID: 83.3 - 87.4 %OCOROD: 96.8 - 98.8 %
ASPT flight times w.r.t.FSS flight times
Flight time overlaunch mass
Fligh
t tim
e [d
ays]
400
600
800
1000
1200
1400
Launch mass [kg]100 120 140 160 180 200 220 240 260
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 92.0 - 97.8 %OCORID: 111.4 - 117.2 %OCOROD: 137.6 - 143.9 %
ASPT flight times w.r.t.FSS flight times
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 18 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-Mars Rendezvous:Mission Description
The solar sails are launched from Earth onto an interplanetarytrajectory with zero hyperbolic excess energy (C3 = 0)
The solar sails have to spiral away from the Sun
Orbit-to-orbit rendezvous
Final constraints for successful rendezvous:
Distance to Mars 5.5 105 km (< mean SOI)Relative velocity to Mars 0.1 km/s
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 19 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-Mars Rendezvous:Results
Flight time overcharacteristicacceleration Flig
ht ti
me
[day
s]
1000
1500
2000
2500
3000
3500
Characteristic acceleration [mm/s2]0.1 0.12 0.14 0.16 0.18 0.2
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 73.2 - 81.5 %OCORID: 83.6 - 88.6 %OCOROD: 96.3 - 99.6%
ASPT flight times w.r.t.FSS flight times
Flight time overlaunch mass
Fligh
t tim
e [d
ays]
1000
1500
2000
2500
3000
3500
Launch mass [kg]100 120 140 160 180 200 220 240 260
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 91.3 - 102.6%OCORID: 112.2 - 121.3 %OCOROD: 137.2 - 153.5 %
ASPT flight times w.r.t.FSS flight times
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 20 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Mission Description
1996FG3 is of great scientific interest and can be accessed relativelyeasily
The solar sails are launched from Earth onto an interplanetarytrajectory with zero hyperbolic excess energy (C3 = 0)
The solar sails have to perform a considerable change of orbitaleccentricity (eEarth = 0.0167 e1996FG3 = 0.3499)Orbit-to-orbit rendezvous
Final constraints for successful rendezvous:
Distance to 1996FG3 3.0 105 kmRelative velocity to 1996FG3 0.1 km/s
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 21 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Results
Flight time overcharacteristicacceleration Flig
ht ti
me
[day
s]
800
1000
1200
1400
1600
1800
2000
2200
2400
Characteristic acceleration [mm/s2]0.1 0.12 0.14 0.16 0.18 0.2
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 87.6 - 89.0 %OCORID: 95.8 - 98.5 %OCOROD: 108.4 - 111.3 %
ASPT flight times w.r.t.FSS flight times
Flight time overlaunch mass
Fligh
t tim
e [d
ays]
800
1000
1200
1400
1600
1800
2000
2200
2400
Launch mass [kg]100 120 140 160 180 200 220 240 260
real FSSAkimaInt real FSSOCIRIDAkimaInt OCIRIDOCORIDAkimaInt OCORIDOCORODAkimaInt OCOROD
OCIRID: 101.1 - 114.0%OCORID: 122.4 - 136.6 %OCOROD: 149.4 - 165.8 %
ASPT flight times w.r.t.FSS flight times
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 22 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Trajectory and Steering Angles
21
01
2 21
01
2
0.04
0.02
0
0.02
0.04
y [AU]x [AU]
z [AU]
TrajectoryEarth orbit1996FG3 orbit
FSS withac = 0.10 mm/s
2
Pitch
ang
le [d
eg]
0
20
40
60
80
Clock angle [deg]
0
50
100
150
200
250
300
350
Flight time [days]0 500 1000 1500 2000
Steering angles(black: pitch angle, blue: clock angle)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 23 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Trajectory and Steering Angles
21
01
2 21
01
2
0.04
0.02
0
0.02
0.04
y [AU]x [AU]
z [AU]
TrajectoryEarth orbit1996FG3 orbit
OCIRID withac = 0.10 mm/s
2
Pitch
ang
le [d
eg]
35
40
45
50
55
Clock angle [deg]
0
50
100
150
200
Flight time [days]0 500 1000 1500
Steering angles(black: pitch angle, blue: clock angle)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 24 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Trajectory and Steering Angles
21
01
2 21
01
2
0.04
0.02
0
0.02
0.04
y [AU]x [AU]
z [AU]
TrajectoryEarth orbit1996FG3 orbit
OCORID withac = 0.10 mm/s
2
Pitch
ang
le [d
eg]
35
40
45
50
55
Clock angle [deg]
0
50
100
150
200
250
300
350
Flight time [days]0 500 1000 1500 2000
Steering angles(black: pitch angle, blue: clock angle)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 25 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Earth-1996FG3 Rendezvous:Trajectory and Steering Angles
21
01
2 21
01
2
0.04
0.02
0
0.02
0.04
y [AU]x [AU]
z [AU]
TrajectoryEarth orbit1996FG3 orbit
OCOROD withac = 0.10 mm/s
2
Pitch
ang
le [d
eg]
35
40
45
50
55
Clock angle [deg]
0
50
100
150
200
250
300
350
Flight time [days]0 500 1000 1500 2000
Steering angles(black: pitch angle, blue: clock angle)
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 26 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Discussion of the Results
Mean ASPT flight time with respect to FSS flight time for the samecharacteristic acceleration:
Earth-Venus Earth-Mars Earth-1996FG3
OCIRID 76.6 % 78.3 % 88.4 %OCORID 85.7 % 85.9 % 97.3 %OCOROD 97.8 % 98.4 % 109.2 %
For the same characteristic acceleration, the ASPT performsgenerally better than the FSS
Worse ASPT performance for the Earth-1996FG3 rendezvous than forthe Earth-Venus and the Earth-Mars rendezvous
For the Earth-1996FG3 rendezvous, optimal solar sail steering requiressmall and large pitch angles due to the large eccentricity change
Because of the constrained ASPT pitch angle(35 deg 55 deg), the eccentricity can not be changedeffectively
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 27 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Discussion of the Results
Mean ASPT flight time with respect to FSS flight time for the samelaunch mass:
Earth-Venus Earth-Mars Earth-1996FG3
OCIRID 94.4 % 97.1 % 108.8 %OCORID 115.1 % 117.7 % 131.6 %OCOROD 141.6 % 145.1 % 160.3 %
For the same launch mass, the ASPT performs generally worse thanthe FSS
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 28 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Summary and Conclusions
According to previous theoretical studies, the compound solar sailmay excel the performance of a flat solar sail
We have introduced a realistic design concept and simulation modelfor a compound solar sail, termed Advanced Solar Photon Thruster,or ASPT, that does not suffer from oversimplifications
To compare its performance with respect to the conventional flatsolar sail, we have calculated time-optimal transfer trajectories toVenus, Mars, and a near-Earth asteroid
The ASPT typically achieves shorter flight times than a flat solar sailwith the same characteristic acceleration
However, it is not superior to the flat solar sail, if one compares thelaunch masses when realistic optical properties and structural massesare assumed
Our results show that the smart idea of a compound solar sail doesnot withstand closer scrutiny. Based on technical complexity,scalability, and performance, the flat solar sail seems to provide thebetter design choice
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 29 / 30
Introduction
FSS
SPT
ASPT
ASPT Model
SRP ForceModel
EngineeringChallenges
PerformanceParameters
MissionAnalysis
Earth-VenusRendezvous
Earth-MarsRendezvous
Earth-NEARendezvous
Discussion
Summary andConclusions
Mission Analysis andPerformance Comparison for an
Advanced Solar Photon Thruster
Bernd Dachwald1 and Patrick Wurm2
1Faculty of Aerospace Engineering,FH Aachen University of Applied Sciences, Germany
2Institute of Aeronautics and Astronautics,RWTH Aachen University, Germany
2nd International Symposium on Solar Sailing, New York City2022 July 2010
Bernd Dachwald and Patrick Wurm Advanced Solar Photon Thruster 30 / 30
IntroductionThe Flat Solar Sail (FSS)The Solar Photon Thruster (SPT)The Advanced Solar Photon Thruster (ASPT)
ASPT ModelSRP Force ModelEngineering ChallengesPerformance Parameters
Mission AnalysisEarth-Venus RendezvousEarth-Mars RendezvousEarth-NEA RendezvousDiscussion of the Results
Summary and Conclusions
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