JSC
Earth Moon Libration Point (L1) Gateway Station –
Libration Point Transfer Vehicle Kickstage Disposal Options
Presented to the International Conference On Libration Point Orbits and Applications
June 10-14, 2002, Parador d’Aiguablava, Girona, Spain
G. L. Condon, NASA – Johnson Space Center / EG5, 281-483-8173, gerald.l.condon1@jsc.nasa.gov
C. L. Ranieri, NASA – Johnson Space Center
S. Wilson, Elgin Software, Inc.
1
Acknowledgements
•
•
•
•
JSC
Chris Ranieri* – orbit lifetime analysis
Joey Broome# – STK/Astrogator validation/movie
Sam Wilson+ – software development / analysis
Daniel M. Delwood + – analysis
2
* JSC Co-op
# JSC Engineer
+ Elgin Software, Inc.
Outline
JSC
• Introduction
• Expeditionary vs. Evolutionary Missions
• Libration Point Transfer Vehicle (LTV)
Kickstage Disposal Options
• Geocentric Orbit Lifetime
• Conclusion
3
Introduction
JSC
The notion of human missions to libration points has
been proposed for more than a generation
A human-tended Earth-Moon (EM) libration point
(L1) Gateway Station could support an infrastructure
expanding human presence beyond low Earth orbit
and serve as a staging location for human missions
to:
–
–
–
–
–
The lunar surface
Mars
Asteroids, comets
Other libration point locations (NGST, TPF)
…
The Gateway concept supports an Evolutionary vs.
Expeditionary approach to exploration …
4
Expeditionary vs. Evolutionary JSC
• Single mission or mission set
• Completed mission satisfies
ng
vici
r
e
s
mission objectives
ope
c
s
ele
to t
s
n
a
• Closed-end missions
Hum
SunSun
Earth
Libration
Points
Humans to L1
Examples
Earth Orbit
Operations
Apollo
Skylab
Apollo-Soyuz Test
Project
Columbus’ voyage of
discovery to the
new world
Humans
to Moon
Hu
m
an
st
oM
The
Moon
EarthEarthMoon
Libration
Points
ar
s
Mars
Mars Orbit
Near Earth
Asteroids
Phobos /
Deimos
5
Expeditionary vs. Evolutionary JSC
• Ongoing missions
• Open-end missions on which
other missions can build
• Greater initial capital investment
SunSun
Earth
Libration
Points
Humans (to L1, Moon, Telescope
Servicing, and Mars)
Earth Orbit
Operations
EarthEarthMoon
Libration
Points
The
Moon
Examples
 International Space Station program
 Voyages of Prince Henry the Navigator
of Portugal
 The man chiefly responsible for
Portugal’s age of exploration
Near Earth
Asteroids
Mars
Mars Orbit
Phobos /
Deimos
6
Earth-Moon L1 – Gateway for Lunar Surface Operations
JSC
• Celestial park-n-ride
• Close to home
(3-4 days)
• Staging to:
–
–
–
–
–
Moon
Sun-Earth L2
Mars
Asteroids
…
Mars
Near Earth
Asteroids
NGST
TPF
Sun-Earth L2
7
Gateway Operations – LTV Kickstage Disposal JSC
•
•
Ongoing Gateway operations require robust
capability for delivery & retrieval of a crew
Human occupation of the Gateway Station requires
a human transfer system in the form of a Libration
Point Transfer Vehicle (LTV) designed to ferry the
crew between low Earth orbit and the Gateway
Station.
A key element of such a system is the proper
and safe disposal of the LTV kickstage
8
Purpose
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1. Identify concepts concerning the role of humans in
libration point space missions
2. Examine mission design considerations for an EarthMoon libration point (L1) gateway station
3. Assess delta-V (DV) cost to retarget Earth-Moon L1
Gateway-bound LTV spacecraft kickstage to a
selected disposal destination
9
LTV Kickstage Disposal Options JSC
LTV/Kickstage
Injection Toward L1
LTV / Kickstage
Separation
LTV Crew Cab
Continues to L1
LTV Kickstage
Diverted to Disposal Destination
Options considered for LTV kickstage disposal:
1.
2.
3.
4.
5.
Lunar Swingby to Heliocentric Orbit (HO)
Lunar Vertical Impact (LVI), typifies any lunar impact
Direct Return to Remote Ocean Area (DROA)
Lunar Swingby to Remote Ocean Area (SROA)
Transfer to Long Lifetime Geocentric Orbit (GO)
10
Methodology
JSC
• Evaluation Timeframe - 2006 Mission Year Chosen
– Survey two week period of L1 arrivals yielding max (80.2o) and min
(23.0o) plane changes ever possible at L1 for crewed spacecraft
• 28.6o lunar orbit inclination; coplanar departure from 51.6o ISS orbit
• Moon goes from perigee to apogee during the chosen 2-week period; begins
and ends on the equator
Maximum L1 Arrival
Wedge Angle @ Libration
Point Arrival = 80.2o
Earth Parking
Orbit
Lunar Orbit Inclination
= 28.6o (max. ever)
Lunar Orbit Inclination
Earth
Moon
28.6o
Earth Equator
Earth Equator
51.6o
L1
80.2o
(Between Earth
And Moon)
• Combine max and min plane changes with arrivals at L1 perigee and apogee
by looking at both choices of arrival velocity azimuth (northerly and
southerly) for every arrival date (requires arbitrary ISS orbit nodes)
11
Methodology (continued)
JSC
• HO, LVI, DROA, SROA, and GO maneuver times
designed to minimize DV for stage disposal subject to
imposed constraints
– Solutions considered to be a practical attempt to minimize these
maneuver DVs (e.g.: coplanar kickstage deflection maneuver
assumed optimal for some disposal options) and not rigorous
global optimizations Analysis
• Analysis Tools
– Earth Orbit to Lunar Libration (EOLL) scanner*
• Four-body model
– Earth, moon, sun, spacecraft
– Jean Meeus's analytic lunar and solar ephemerides
• Overlapped conic split boundary value solutions individually
calibrated to multiconic accuracy
– Validation with STK/Astrogator
12
* Developed and updated by Sam Wilson
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
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E2LP-Based D ata
Earth Parking Orbit to Earth-Moon L1 DV Cost vs. Flight Time
6. Kickstage flies behind trailing
limb of Moon to achieve
geocentric C3>0 (hence
departure from EarthMoon system)
6000
Total D V (m/s), Earth Dep. + L1 Arr.
Initial Circ. Earth Parking Orbit Altitude = 407 km
o
Orbit Incl. Wrt Equator = 51.6
o
Orbit Incl. wrt Earth-Moon Plane = 81
5500
Arrival at Lunar
Apogee
5000
Moon
3.5 day transfer
Arrival at Lunar
Perigee
L1
4500
Min. DV @ 82 Hours = 4040 m/ s
5. Spacecraft arrives
at L1
4000
Min. DV @ 100 Hours = 3940 m/ s
3500
0
10
20
30
40
50
60
70
8084 90
100
110
120
130
140
150
Flight Time (hours)
Nominal crew vehicle trajectory to
Earth-Moon L1
-Trip time = 3.5 days (84 hours)
- Braking maneuver at L1
1. Libration Point Transfer Vehicle (LTV)
spacecraft with Kickstage in
initial 407 x 407 km parking orbit
Earth
2. . Kickstage injects spacecraft
& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performs
maneuver to achieve close
encounter with moon
3. Coast phase;
Kickstage jettison
13
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
Video
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14
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
JSC
Heliocentric Orbit (HO) Transfer DV vs. Libration Point Arrival Time
DV Cost to Deflect LTV Kickstage from L1 Target to Heliocentric Orbit Via Lunar Swingby
140
130
Moon at
Perigee
Moon at
Apogee
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Deflection DV (m/s)
120
110
100
DV for Southerly Lunar Libration
Point Arrival Azimuth
DV for Northerly Lunar Libration
Point Arrival Azimuth
90
80
70
60
50
40
30
20
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Northerly Lunar Libration Point Arrival Azimuth
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Southerly Lunar Libration Point Arrival Azimuth
10
Heliocentric Orbit Achieved Via Lunar Orbit
Geocentric V-infinity > 800 m/s after Lunar Swingby
0
10/6/06 0:00
10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
15
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
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• Advantages
– No Earth or Lunar disposal issues (e.g., impact location, debris
footprint, litter)
– Relatively low disposal DV cost
• Disadvantages
– Heliocentric space litter (kickstage heliocentric orbit near that of
the earth)
– Periodic possibility of re-contact with Earth
16
Option 2. Lunar Vertical Impact (LVI)
JSC
6. Kickstage impacts
Lunar surface
Moon
L1
5. Spacecraft arrives
at L1
1. Lunar Transfer Vehicle (LTV)
spacecraft with Kickstage in
initial 407 x 407 km parking orbit
Earth
2. Kickstage injects spacecraft
& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performs
maneuver to achieve
lunar impact
3. Coast phase
Kickstage jettison
17
Option 2. Lunar Vertical Impact (LVI)
Video
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18
Option 2. Lunar Vertical Impact (LVI)
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Lunar Vertical Impact (LVI) Transfer DV vs. Libration Point Arrival Time
DV Cost to Deflect LTV Kickstage from L1 Target to Lunar Vertical Impact
140
DV for Northerly Lunar Libration
Point Arrival Azimuth
130
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
120
110
Deflection DV (m/s)
100
DV for Southerly Lunar Libration
Point Arrival Azimuth
90
80
70
60
50
40
30
20
10
0
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Northerly Lunar Libration Point Arrival Azimuth
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Southerly Lunar Libration Point Arrival Azimuth
Moon at
Perigee
10/6/06 0:00
Moon at
Apogee
10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
19
Option 2. Lunar Vertical Impact (LVI)
JSC
• Advantages
– No Earth disposal issues (e.g., impact location, debris footprint,
litter, possible recontact)
• Disadvantage
– Lunar litter
– Relatively high disposal DV cost
20
Option 3. Direct Return to Remote Ocean Area (DROA)
5. Spacecraft arrives
at L1
JSC
Moon
L1
1. Lunar Transfer Vehicle (LTV)
spacecraft with Kickstage in
initial 407 x 407 km parking orbit
Earth
2. Kickstage injects spacecraft
& kickstage onto transfer
trajectory toward L1
6.
Kickstage returns to
Earth for ocean
impact
4. Jettisoned kickstage performs
maneuver to achieve 20 atmospheric
entry angle and mid-ocean impact
3. Coast phase;
Kickstage jettison
21
Option 3. Direct Return to Remote Ocean Area (DROA)
DV Budget Gives 240o Longitude Control
•
Entry flight path angle = -20o selected
–
•
Confines surface debris footprint
Impact latitude is determined by:
1.
2.
Spacecraft date of arrival at L1 and
Choice of northerly or southerly velocity azimuth at L1 arrival
•
•
JSC
From an established (e.g., ISS) earth orbit, these two degrees of freedom typically yield
two or three transfer opportunities to L1 every month.
Impact longitude depends on (1.) and (2.) above, plus
3. Atmospheric entry time chosen for the kickstage
•
•
Minimizing the kickstage deflection DV determines an unique (and essentially random)
impact longitude for an arbitrary transfer opportunity.
Kickstage budget gives 240 degrees of longitude control
–
–
If kickstage disposal is not to constrain the primary mission, the kickstage DV
budget must be sufficient to allow the impact point to be moved from its
minimum-DV location to an Atlantic or a Pacific mid-ocean line.
At any latitude, the maximum longitude difference between the chosen midocean lines is 240 degrees (see next chart).
22
Option 3. Direct Return to Remote Ocean Area (DROA)
Shaded Region Contains Max Longitude Difference (240o) Between
Mid-Atlantic and Mid-Pacific Target Lines
JSC
x
x
x
x
x
x
x
x
x
x
x
x
x
xx
x
Ocean Impact
demo location
x
x
x
x
23
Option 3. Direct Return to Remote Ocean Area (DROA)
Video
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24
Option 3. Direct Return to Remote Ocean Area (DROA)
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Direct Remote Ocean Area (DROA) DV vs. Libration Point Arrival Time
140
Deflection DV (m/s)
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
130
DV Cost to Deflect LTV Kickstage from L1 Target to Remote Ocean Area Impact
Moon at
Perigee
Moon at
Apogee
120
Upper Stage Disposal into Remote Ocean Area
-----------------------------------------------------------------Direct entry (No Lunar Swing-by)
20 deg Entry Flightpath Angle
240 deg Impact Longitude Spread
110
100
90
DV for Southerly Lunar Libration
Point Arrival Azimuth
80
70
60
50
DV for Northerly Lunar Libration
Point Arrival Azimuth
40
30
20
10
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Northerly Lunar Libration Point Arrival Azimuth
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Southerly Lunar Libration Point Arrival Azimuth
0
10/6/06 0:00
10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
25
Option 3. Direct Return to Remote Ocean Area (DROA)
JSC
• Data shown represent best of two solution subtypes
– Generally there are two local optima for the location of the
kickstage maneuver point in the earth-to-L1 transfer trajectory, of
which the better one was always chosen
• Advantages
– Assuming kickstage disposal is not allowed to constrain the
primary mission, this option is one of three (HO,DROA,GO)
requiring the lowest DV budget that could be found (slightly more
than 90 m/s in all three cases)
– Avoidance of close lunar encounter, combined with steep entry
over wide areas of empty ocean minimizes criticality of navigation
and maneuver execution errors
• Disadvantages
– Not appropriate if kickstage contains radioactive or other
hazardous material
26
Option 4. Lunar Swingby to Remote Ocean Area (SROA)
JSC
5. Spacecraft arrives
at Earth-Moon L1
L1
6.
1. Lunar Transfer Vehicle (LTV)
spacecraft with Kickstage in
initial 407 x 407 km parking orbit
Kickstage passes in
front of Moon’s
leading limb and
returns to Earth for
ocean impact
4. Jettisoned kickstage performs
maneuver to achieve close
encounter with moon
2. Kickstage injects spacecraft
& kickstage onto transfer
trajectory toward L1
3. Coast phase;
Kickstage jettison
27
Option 4. Lunar Swingby to Remote Ocean Area (SROA)
JSC
28
Option 4. Lunar Swingby to Remote Ocean Area (SROA)
JSC
Swing-by Remote Ocean Area (SROA) Transfer DV vs. Libration Point Arrival Time
DV Cost to Deflect LTV Kickstage from L1 Target to Remote Ocean Area Impact via Lunar Swing-by
140
* DV represents lower bound
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Deflection DV* (m/s)
130
120
DV for Southerly Lunar Libration
Point Arrival Azimuth
110
100
90
DV for Northerly Lunar Libration
Point Arrival Azimuth
80
70
60
50
40
30
20
10
0
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Northerly Lunar Libration Point Arrival Azimuth
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Southerly Lunar Libration Point Arrival Azimuth
Moon at
Perigee
10/6/06 0:00
Moon at
Apogee
10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
29
Option 4. Lunar Swingby to Remote Ocean Area (SROA)
•
•
JSC
Advantages
– None identified
Disadvantages
– This option requires a greater DV budget than any other one examined.
• The DV values shown are minimum values for impact at an essentially random
location.
• The DV required for longitude control will be even higher
– Inherent sensitivity of this kind of trajectory is almost certain to require
extended lifetime of the control system to perform midcourse corrections
before and after perisel passage
30
Option 5. Transfer to Long Lifetime Geocentric Orbit (GO)
JSC
4b. Alternatively, kickstage may raise perigee with maneuver
at/near apogee of Earth-L1 transfer orbit
Moon
L1
5. Crew module arrives
at L1
1. Lunar Transfer Vehicle (LTV)
crew module with Kickstage in
initial 407 x 407 km parking orbit
6.
Earth
2. Kickstage injects crew module
& kickstage onto transfer
trajectory toward L1
Kickstage
continues on
parking orbit
4a. Jettisoned kickstage performs
retargeted Earth parking orbit
maneuver
3. Coast phase
Kickstage jettison
31
Option 5. Transfer to Long Lifetime Geocentric Orbit (GO)
Video
JSC
32
Option 5. Transfer to Long Lifetime Geocentric Orbit (GO)
JSC
GO DV vs. Libration Point Arrival Time
Cost to Deflect LTV Kickstage from L1 Target to Long Lifetime Geocentric Orbit
140
Deflection DV (m/s)
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
130
Moon at
Perigee
Moon at
Apogee
120
110
100
Perigee: 6,600 km
Apogee Range: 300,000 - 370,000 km
DV for Southerly Lunar Libration
Point Arrival Azimuth
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Northerly Lunar Libration Point Arrival Azimuth
90
80
70
60
DV for Northerly Lunar Libration
Point Arrival Azimuth
50
40
30
20
10
Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
Southerly Lunar Libration Point Arrival Azimuth
0
10/6/06 0:00
10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
33
Option 5. Transfer to Long Lifetime Geocentric Orbit (GO)
•
JSC
Advantages
– Preferable to deliberate ocean impact if kickstage carries hazardous material
– In 4 of the 22 cases studied, the DV requirement for GO disposal (into an orbit
having a perigee altitude of 6600 km and an apogee altitude in the range of 300000
– 370000 km) was less than 12 m/s, which is much lower than that found for any
other option considered.
– Assuming the 22 cases represent an unbiased sample of all possible transfers
between earth orbit and L1, this implies that a 12 m/s budget would suffice if it
were permissable to forgo all but about 20% of the otherwise-available transfer
opportunities.
•
Disadvantages
– More orbital debris in the earth-moon system
– The 12 m/s budget described above would increase the average interval between
usable transfers to something like 50 days, as opposed to 10 days if transfer
utilization were not allowed to be constrained by the disposal DV budget (which
would then have to be more than 90 m/s).
– To achieve acceptable orbit lifetime, lunar and solar perturbations may necessitate a
higher perigee and/or lower apogees, either of which will increase the required DV.
34
Summary Results
140
Moon at
Perigee
HO, LVI, DROA, SROA, GO Transfer Delta-V vs. Libration Point Arrival Time
DV Cost to Deflect LTV Kickstage from L1 Target to Disposal Destination
JSC
Moon at
Apogee
130
SROA N
120
SROA S
LVI N
110
LVI S
Deflection DV (m/s)
100
HO N
DROA S
90
HO S
80
70
GO N
60
50
40
30
20
10
DROA N
Key:
HO
LVI
DROA
SROA
GO
N=North L1 Arrival Azimuth
S=South L1 Arrival Azimuth
=
=
=
=
=
Heliocentric Orbit
Lunar Vertical Impact
Direct Remote Ocean Area
(Lunar) Swingby Remote Ocean Area
Geocentric (Parking) Orbit
GO S
0
10/6/06 0:00 10/8/06 0:00 10/10/06 0:00 10/12/06 0:00 10/14/06 0:00 10/16/06 0:00 10/18/06 0:00 10/20/06 0:00
Libration Point Arrival Time (mm/dd/yy
hh:mm)
35
JSC
Geocentric Orbit Lifetime Study
Geocentric Orbit Lifetime
JSC
• Spacecraft (kickstage) initial condition – Apogee
of LEO to EM L1 transfer orbit
– Apogee range: 300,000 km – 371,000 km
– Perigee range: 6600 km – 20,000 km
• 45 test case runs
• Results
– 56% of the test cases impacted the Earth within 10
years
– Spacecraft cannot be left on transfer orbit
– Further study to determine safe Apogee and Perigee
Ranges
37
LTV Orbit Lifetime
JSC
Lifetime for LTV Placed in Geocentric Orbit (GO)
50
40
20
Orbit
Lifetime
(yrs)
0
-16
36
86
25
52
96
09
35
35
10
51
35
36
11
34
29
36
34
00
67
34
83
36
32
78
29
32
06
26
32
37
64
31
00
92
30
06
56
30
64
02
30
31
67
31
15000
7500
Perigee (km)
6600
Apogee (km)
00
Note: A negative lifetime
indicates LTV kickstage
experienced either heliocentric
departure from the Earth-Moon
system or Lunar impact
38
45 transfer orbits in sample space
Summary
JSC
• Recommend Direct Remote Ocean Area impact disposal for cases
without hazardous (e.g., radioactive) material on LTV kickstage
–
–
–
–
Controlled Earth contact
Relatively small disposal DV
Avoids close encounter with Moon
Trajectories can be very sensitive to initial conditions (at disposal
maneuver)
•
DV to correct for errors is small
• Recommend Heliocentric Orbit disposal for cases with hazardous
material on LTV kickstage
– No Earth or Lunar disposal issues (e.g., impact location, debris footprint,
litter)
– Relatively low disposal DV cost
– Further study required to determine possibility of re-contact with Earth
39
JSC
Additional Slides
Summary Results
JSC
SWW:dmd
Earth-to-LL1 Transfer and Upper Stage Disposal Data
11-May-02
All transfers involve coplanar departure from circular earth parking orbit having an altitude of 407 km and an inclination of 51.6 deg
GO,DROA, LVI, HO, and SROA maneuver times selected to minimize delta-v for stage disposal
Arr Time
(Nominal)
2006 Oct
10/6/06 4:00
10/7/06 4:00
10/8/06 4:00
10/9/06 8:00
10/11/06 0:00
10/12/06 8:00
10/13/06 18:00
10/15/06 18:00
10/17/06 4:00
10/18/06 12:00
10/19/06 18:00
Lunar L1
RA
deg
-1.0
12.4
26.2
42.9
68.1
88.5
109.2
135.4
151.8
166.2
179.2
RA
RAN
RANo
iEMP
EOD
LPA
GO
DROA
LVI
HO
SROA
OC
MC
Decl.
deg
-0.1
7.2
14.0
20.7
27.1
28.7
27.2
20.7
14.0
6.9
-0.1
Dist.
1000
km
304
304
305
309
317
324
332
339
343
344
345
Earth
Park Orbit
RAN Epoch
2006 Oct
10/2/06 16:00
10/3/06 16:00
10/4/06 16:00
10/5/06 20:00
10/7/06 12:00
10/8/06 20:00
10/10/06 6:00
10/12/06 6:00
10/13/06 16:00
10/15/06 0:00
10/16/06 6:00
Northerly LL1 Arrival Azimuth
Park
Xfr
Maneuver Delta-V, m/s
Orbit Orbit EOD LPA GO DROA
LVI
HO
RANo iEMP MC MC MC MC MC OC OC
-1.0 23.7 3061 782 52 50
87 88 66
6.7 24.0 3059 784 59 45
87 88 66
14.7 24.3 3060 781 61 42
87 88 65
25.0 28.7 3060 781 65 43
93 94 71
43.0 35.0 3063 776 63 53 101 101 78
61.2 44.0 3063 787 62 59 110 109 86
84.0 55.2 3066 810 59 61 115 115 92
117.6 69.2 3071 851 61 58 117 118 96
140.3 75.4 3072 875 63 53 116 117 95
160.7 78.7 3074 890 65 51 115 117 95
179.3 80.1 3074 900 66 49 114 117 94
SROA
OC
106
106
111
117
126
132
135
134
132
132
131
Southerly LL1 Arrival Azimuth
Park
Xfr
Maneuver Delta-V, m/s
Orbit Orbit EOD LPA GO DROA
LVI
RANo iEMP MC MC MC
MC MC OC
178.9 81.0 3060 984 91
55 104 106
198.1 79.8 3061 980 91
55 105 106
217.7 75.9 3059 960 90
58 106 106
240.9 68.2 3059 916 87
55 107 108
273.2 54.4 3064 838 77
58 109 109
295.8 44.3 3063 786 61
62 110 109
314.5 35.9 3066 748 33
69 109 109
333.3 28.0 3070 726
7
83 107 107
343.4 24.9 3072 724
5
89 105 106
351.8 23.3 3073 727 10
92 104 105
359.2 23.3 3073 733 11
93 104 106
Right Ascension
Right Ascension of Ascending Node
Right Ascension of Ascending Node at RAN Epoch
Inclination of Xfr Orbit wrt Earth-Moon Plane
Earth Orbit Departure to L1 Lunar Libration Point
Libration Point Arrival (3.5 days after EOD)
Upper Stage Disposal in "Safe" Geocentric Orbit (6600 km Perigee Alt, 300000 - 370000 km Apogee Alt)
Upper Stage Disposal in Remote Ocean Area (Direct,20 deg Atmospheric Entry Angle, 240 deg Longitude Spread)
Upper Stage Disposal on Lunar Surface (Vertical Impact)
Upper Stage Disposal in Heliocentric Orbit (via Lunar Swingby)
Upper Stage Disposal in Remote Ocean Area (via Lunar Swingby)
Overlapped Conic Trajectory
Multi-Conic Trajectory
LVI: Use none on abort
41
HO SROA
OC
OC
87 124
88 126
87 128
87 131
86 132
87 132
83 129
83 124
82 120
82 120
81 121
Earth Moon L1 - Orbit Lifetime Study
JSC
• Possible future missions to Earth-Moon
(EM) L1 Libration Point – Gateway Station
• Need to develop safe disposal guidelines for
such a mission
– Do not want nuclear payloads crashing into
Earth
42
Earth Moon L1 Study
•
JSC
Three orbit lifetime studies using
STK/Astrogator:
1. S/c left on transfer orbit to EM L1 with low perigee
and an apogee near EM L1 (343,000 km)
2. S/c left at EM L1 with no relative velocity to EM L1
and no station keeping
3. S/c left at EM L1 with a parametric scan of impulsive
delta-Vs of varying magnitudes and directions (0 360 degrees; 0 - 500 m/s)
•
Propagation utilizes multiple gravitation sources
– Earth (central), Sun, Moon, Mars, and Jupiter
•
Coordinate System defined with origin at EM L1
43
Earth-Moon L1 - Orbit Lifetime
Spacecraft Initially at L1
JSC
• The spacecraft possesses zero initial position and velocity
relative to Earth-Moon L1
• With no station-keeping maneuvers, spacecraft drifts from
L1 position
• EM L1 location shifts as the Earth and Moon positions
change
– EM L1 Earth distance: 302830 km – 345298 km
• No Earth Impacts found – Either lunar impacts or the s/c
uses the lunar gravity to go heliocentric
– Un-discernable pattern (given data sample space)
44
L1 Orbit Lifetime vs. EM L1 Position in Lunar Cycle
JSC
Orbit Lifetime and Earth-Moon L1 Distance vs. Days In a Lunar Cycle
Based on a free-drifting (uncontrolled) spacecraft with initial conditions at the Earth-Moon L1 point
120
350000
Moon at
Perigee
Moon at
Apogee
300000
100
EarthMoon L1
Distance
250000
200000
60
150000
40
100000
Orbit lifetimes <100 years result in either lunar impact or heliocentric trajectory (via lunar fly-by)
No Earth impacts occurred (for these 18 sample propagations)
20
50000
0
0
0
4
8
12
16
20
24
28
32
36
40
Days
45
Earth-Moon L1 Distance (km)
Orbit
Lifetime
80
Orbit Lifetime (yrs)
Moon at
Perigee
EM L1 Orbit Lifetime w/ Delta-Vs
JSC
• Seven Total Earth Impacts
• Earth Impact for a case with a Δv as small as
10 m/s
• No discernible pattern to results by either
magnitude, direction, or epoch for
maneuver
46
Orbit Lifetime for Spacecraft at L1
Initial DV of 10-500 m/s; 360o Range Relative to Initial Velocity
JSC
Lifetime Results For Satellite Starting at EM L1
100+ Years in
Geocentric Orbit
Earth Impact following
Heliocentric Departure
44%
Heliocentric
Departure
1%
2%
2% Earth Impact
51%
Lunar
47
Maneuver at Earth-Moon L1 (345,187 km apogee)
JSC
DV = 100 m/s Over 360o Range of Direction
100 Years
1.71 Years
100 Years
0.033 years
100 Years
In Earth
Orbit
L1 Velocity
Direction
Earth Impact
Lunar Impact
0.618 Years
100 Years
0.402 years
Escape to Heliocentric Orbit
48
EM L1 Orbit Lifetime – Future Work
JSC
• Further studies to better define safe disposal
guidelines for s/c launched to EM L1
– Further examine lifetimes for s/c at or near EM
L1 position and velocity
– Examine transfers to other disposal orbits,
possibly b/w GEO and EM L1 that are less
affected by lunar perturbations
– Write for paper to be possibly presented in
Spain on this work
49
Human Presence in Space
JSC
• Demonstrated
benefit to human
presence
– Hubble Space
Telescope deploy
and repair
– Retrieval of Long
Duration Exposure
Facility
– Retrieval of Westar
and Palapa satellites
50
Libration Point Missions
JSC
• Earth-Moon L1
– Gateway station
• Sorties to the Moon
• Satellite deploy, servicing
– Next Generation Space Telescope
– Terrestrial Planet Finder
– Staging area for interplanetary and asteroid missions
• Earth-Moon L2
– Robotic relay satellites for backside operations
• Bent pipe communications
• Navigation aid
• Sun-Earth L2
51
Lunar Mission: Libration Point vs. LOR
JSC
Mission Scenario Advantages
Earth-Moon L1
– No lunar departure
injection window
– Reusability
– Protection from failed
station-keeping
– Specialized vehicle
design
Lunar Orbit
Rendezvous (LOR)
Shorter mission
duration
Lower overall DV cost
Fewer critical
maneuvers required
52
Considerations for Human Lunar L1 Missions
JSC
• 18 year lunar inclination cycle
• Eccentricity of lunar orbit
• Performance cost versus time
• Frequency of outbound & inbound
opportunities
53
18 Year Lunar Inclination Cycle JSC
54
18 Year Lunar Inclination Cycle JSC
L1
23.0o
(Between Earth
And Moon)
Lunar Orbit
Inclination
Earth
Lunar Orbit Inclination
51.6o
28.6o
Earth Equator
Earth Equator
Moon
Earth Parking
Orbit
Minimum L1 Arrival
Wedge Angle @ Libration
Point Arrival = 23o
Maximum L1 Arrival
Wedge Angle @ Libration
Point Arrival = 80.2o
Earth Parking
Orbit
Lunar Orbit Inclination
Earth
Moon
28.6o
Earth Equator
51.6o
L1
80.2o
(Between Earth
And Moon)
55
Eccentricity of Lunar Orbit
JSC
E2LP-Based Data
Earth Parking Orbit to Earth-Moon L1 DV Cost vs. Flight Time
6000
Total D V (m/s)
Initial Circ. Earth Parking Orbit Altitude = 407 km
Orbit Incl. Wrt Equator = 51.6 o
Orbit Incl. wrt Earth-Moon Plane = 28.15 o
5000
Arrival at Lunar
Apogee
Arrival at Lunar
Perigee
4000
3000
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Flight Time (hours)
56
Performance Cost vs. Time
JSC
E 2LP -B ased Dat a
Earth Parking Orbit to Earth-Moon L1 D V Cost vs. Flight Time
Initial Circ. Earth Parking Orbit Altitude = 407 km
6000
Orbit Incl. Wrt Equator = 51.6
o
Orbit Incl. wrt Earth-Moon Plane = 28.15
o
5000
EOD+LPA+Libration Point Dep.
D V (m/s)
4000
EOD + LPA
3000
Earth Orbit Departure (EOD)
2000
1000
Libration Point Arrival (LPA)
0
0
10
20
30
40
50
60
70
80
90
100
110
120 130
140
150
Flight Time (hours)
57
Frequency of Outbound and Inbound Opportunities
JSC
EARTH-MOON L1 MISSION OPPORTUNITIES
Coplanar Depart From / Return To ISS
rs
rs s
o u Ho u our s
H
H
r
8
4
32
16 82 Houur s
2
o
8 H rs
4
16 Ho u
8
32
EO H=407.00,I=51.60,RAN=0.00 @ 2009 Jan 09\00:00
LPA/LPD
days
since2009
2009 Jan
Jan 09\00:00
LPA/LPD
Time,Time,
days
since
09\00:00
140
120
OUTBOUND
TRAJECTORIES TO
EARTH-MOON L1
100
Arrival-time
Arrival-time position
position of
of
L1
lies
in
the
departureL1 lies in the departuretime
time ISS
ISS orbit
orbit plane
plane
Earth-to-L1
Earth-to-L1 Opportunity
Opportunity
L1-to-Earth
L1-to-Earth Opportunity
Opportunity
80
60
Co
ta
ns
n
utb
O
t
n
ou
ns
Co
40
h
lig
F
d
t
tan
In
(82
(82 hr.
hr. transfer)
transfer)
(82
hr.
(82 hr. transfer)
transfer)
im
tT
u
bo
e
nd
gh
F li
t
KEY
EOD = Earth orbit departure
EOA = Earth orbit arrival
LPA = Libration point arrival
LPD = Libration point
departure
e
T im
Departure-time
Departure-time
position
position of
of L1
L1 lies
lies in
in
the
the arrival-time
arrival-time ISS
ISS
orbit
orbit plane
plane
20
INBOUND
TRAJECTORIES FROM
EARTH-MOON L1
0
0
20
40
60
80
100
EOD/EOA Time,
daysdays
since since
2009 Jan
09\00:00
EOD/EOA
Time,
2009
Jan 09\00:00
120
140
58
Frequency of Outbound and Inbound Opportunities
JSC
59
JSC
60
Total Transfer DV vs LPA Time
JSC
Total Transfer Delta-V vs. Libration Point Arrival Time
Total transfer DV = EOD DV + LPA DV; LPA Plane Change = 80.2
o
4050
Total Transfer Delta-V (m/s)
4000
Northerly Lunar Libration Point Arrival Azimuth
3950
3900
3850
3800
Southerly Lunar Libration Point Arrival Azimuth
3750
10/6/2006
0:00
10/8/2006
0:00
10/10/2006
0:00
10/12/2006
0:00
10/14/2006
0:00
Libration Point Arrival Time (mm/dd/yy
10/16/2006
0:00
hh:mm)
10/18/2006
0:00
10/20/2006
0:00
61
Transfer DV vs LPA Time
JSC
Transfer Delta-V vs. Libration Point Arrival Time
Total transfer DV = EOD DV + LPA DV
3.5 Day Trip Time
4000
3500
Total Transfer DV
Northerly Lunar Libration Point Arrival Azimuth
Transfer Delta-V (m/s)
3000
Total Transfer DV
Southerly Lunar Libration Point Arrival
Azimuth
Earth Parking Orbit Departure
Northerly and Southerly Lunar Libration Point Arrival Azimuth
2500
2000
1500
Libration Point Arrival DV
Southerly Lunar Libration Point Arrival Azimuth
1000
Libration Point Arrival DV
Northerly Lunar Libration Point Arrival Azimuth
500
0
10/6/2006
0:00
10/8/2006
0:00
10/10/2006
0:00
10/12/2006
0:00
10/14/2006
0:00
Libration Point Arrival Time (mm/dd/yy
10/16/2006
0:00
hh:mm)
10/18/2006
0:00
10/20/2006
0:00
62