NASA Technical Reports Server (NTRS) 20170009412: Lighting Condition Analysis for Mars' Moon Phobos Lighting Condition Analysis for Mars' Moon Phobos Lighting Condition Analysis for Mars' Moon Phobos Lighting Condition Analysis for Mars' Moon Phobos

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by  NASA Technical Reports Server (NTRS)

Lighting Condition Analysis for Mars’
Moon Phobos
Zu Qun Li
Guy de Carufel
Edwin Z. Crues
Paul Bielski

NASA Johnson Space Center
Li, Carufel, Crues, Bielski 1/6/16 1
Overview
•  Motivation
•  Phobos Overview
•  Simulation Development
•  Phobos Lighting Conditions
•  Usage Example:
–  Robotic Lander Preliminary Power Subsystem Analysis
•  Conclusion
Li, Carufel, Crues, Bielski 2/17/16 2
Motivation
•  Need a comprehensive understanding of Phobos’
environment
•  Solar radiation plays crucial role in power and
thermal subsystems
•  Developed a simulation to investigate lighting
conditions on Phobos over one Martian year (July 05
2030 to May 22 2032)
Zu Qun Li 2/17/16 3
Simulation Development
•  Simulation Overview
State vector of Sun
Environment and the planets Phobos
Model Model
Occultation
Model
State vector of State of Phobos and
Sun and Mars its surface information
Output:
Radiation intensity & flux
Li, Carufel, Crues, Bielski 2/17/16 4
Phobos Overview
•  Martian Season
•  Phobos Characteristics
Semi-major axis 9376 km Eccentricity 0.0151
Orbital period 7 h 39.2 min Avg orbital speed 2.138 km/s
1.093° wrt Mars’ equator
Inclination
26.04° wrt ecliptic
Rotation period Synchronous
Li, Carufel, Crues, Bielski 2/17/16 5
Phobos Lighting Conditions
•  Radiation Intensity and Solar Eclipse Time
Eclipse Time and Radiation Intensity: 2462687.5 JD
60 750
•  Radiation intensity
50 700 –  Smaller during
n) 2) northern hemisphere
mi m
t(40 650 W/ summer
bi
Or y (
r sit –  Higher during winter
e n
p30 600 e
e nt •  Solar eclipse time
m I

Ti on –  Longer eclipse time
e ti
s20 550 a
p di during spring and fall
cli a
R
E
–  NO eclipse during
10 500
summer and winter
0 450
00 110000 220000 330000 440000 550000 660000
Sim Time (Earth day)
L =0 L =90 L =180 L =270 L =0
S S S S S
Note: 1 Phobos’ Orbital Period = 7hr 39 mins
Zu Qun Li 2/17/16 6
Phobos Lighting Conditions
View from direction of the Sun Ls = 0
•  Radiation Intensity and Solar Eclipse Time
Eclipse Time and Radiation Intensity: 2462687.5 JD
60 750
•  Radiation intensity
50 700 –  Smaller during
n) 2) northern hemisphere
mi m
t(40 650 W/ summer
bi
Or y (
r sit –  Higher during winter
e n
p30 600 e
e nt •  Solar eclipse time
m I

Ti on –  Longer eclipse time
e ti
s20 550 a
p di during spring and fall
cli a
R
E
–  NO eclipse during
10 500
summer and winter
0 450
00 110000 220000 330000 440000 550000 660000
Sim Time (Earth day)
L =0 L =90 L =180 L =270 L =0
S S S S S
Note: 1 Phobos’ Orbital Period = 7hr 39 mins
Zu Qun Li 2/17/16 7
Phobos Lighting Conditions
View from direction of the Sun Ls = 0
•  Radiation Intensity and Solar Eclipse Time
Eclipse Time and Radiation Intensity: 2462687.5 JD
60 750
•  Radiation intensity
50 700 –  Smaller during
n) 2) northern hemisphere
mi m
t(40 650 W/ summer
bi
Or y (
r sit –  Higher during winter
e n
p30 600 e
e nt •  Solar eclipse time
m I

Ti View from direcontion of t–h eL Sounng er eclipse tiLmse = 90
e ti
s20 550 a
p di during spring and fall
cli a
R
E
–  NO eclipse during
10 500
summer and winter
0 450
00 110000 220000 330000 440000 550000 660000
Sim Time (Earth day)
L =0 L =90 L =180 L =270 L =0
S S S S S
Note: 1 Phobos’ Orbital Period = 7hr 39 mins
From Cosmographia
Zu Qun Li 2/17/16 8
Phobos Lighting Conditions
•  Each frame represents instantaneous surface radiation flux
W/m2
Julian Date: 2462592.5
90
600
60
500
30
)
g 400
e
d
(

e
0
d
u 300
t
i
t
a
L
-30
200
-60
100
-90 0
-180 -135 -90 -45 0 45 90 135 180
Li, Carufel, Crues, Bielski 2/17/16 9
Longitude (deg)
Phobos Lighting Conditions
•  Each frame represents radiant exposure (kJ/m2) for one Phobos orbit (7hr 39min)
KJ/m2
Sub-Mars point
Zu Qun Li 2/17/16 10