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transcript
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JSCEarth 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.govC. L. Ranieri, NASA – Johnson Space Center
S. Wilson, Elgin Software, Inc.
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JSCAcknowledgements
• Chris Ranieri* – orbit lifetime analysis• Joey Broome# – STK/Astrogator validation/movie• Sam Wilson+ – software development / analysis• Daniel M. Delwood + – analysis
* JSC Co-op # JSC Engineer + Elgin Software, Inc.
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JSCOutline
• Introduction
• Expeditionary vs. Evolutionary Missions
• Libration Point Transfer Vehicle (LTV) Kickstage Disposal Options
• Geocentric Orbit Lifetime
• Conclusion
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JSCIntroduction
The notion of human missions to libration points has been proposed for more than a generation
The Gateway concept supports an Evolutionary vs. Expeditionary approach to exploration …
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)– …
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JSCExpeditionary vs. Evolutionary
• Single mission or mission set
• Completed mission satisfies mission objectives
• Closed-end missions
Humans to L1
Humans to telescope servicing
Humans to Mars
The The MoonMoon
Near Earth Near Earth AsteroidsAsteroids
SunSun--Earth Earth
Libration Libration PointsPoints
PhobosPhobos / / DeimosDeimos
Mars Orbit
MarsMars
Earth Orbit Earth Orbit OperationsOperations
EarthEarth--Moon Moon
Libration Libration PointsPoints
Humans to Moon
Humans to L1
Humans to telescope servicing
Humans to Mars
The The MoonMoon
Near Earth Near Earth AsteroidsAsteroids
SunSun--Earth Earth
Libration Libration PointsPoints
PhobosPhobos / / DeimosDeimos
Mars Orbit
MarsMars
Earth Orbit Earth Orbit OperationsOperations
EarthEarth--Moon Moon
Libration Libration PointsPoints
Humans to Moon
ApolloSkylabApollo-Soyuz Test
ProjectColumbus’ voyage of
discovery to the new world
ApolloSkylabApollo-Soyuz Test
ProjectColumbus’ voyage of
discovery to the new world
Examples
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JSCExpeditionary vs. Evolutionary
• Ongoing missions
• Open-end missions on which other missions can build
• Greater initial capital investment
International Space Station program Voyages of Prince Henry the Navigator
of Portugal The man chiefly responsible for
Portugal’s age of exploration
International Space Station program Voyages of Prince Henry the Navigator
of Portugal The man chiefly responsible for
Portugal’s age of exploration
The The MoonMoon
Near Earth Near Earth AsteroidsAsteroids
SunSun--Earth Earth
Libration Libration PointsPoints
PhobosPhobos / / DeimosDeimos
Mars Orbit
MarsMars
EarthEarth--Moon Moon
Libration Libration PointsPoints
Humans (to L1, Moon, Telescope Servicing, and Mars)
Earth Orbit Earth Orbit OperationsOperations
The The MoonMoon
Near Earth Near Earth AsteroidsAsteroids
SunSun--Earth Earth
Libration Libration PointsPoints
PhobosPhobos / / DeimosDeimos
Mars Orbit
MarsMars
EarthEarth--Moon Moon
Libration Libration PointsPoints
Humans (to L1, Moon, Telescope Servicing, and Mars)
Earth Orbit Earth Orbit OperationsOperations
Examples
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JSC
LTV transfers crew from
Earth orbit to L1 station
L1 Gateway Station
Lunar Lander
Moon
Earth
Libration Point Transfer
Vehicle (LTV)
Lunar Lander transfers crew from L1 station to lunar surface
Earth-Moon L1 – Gateway for Lunar Surface Operations
• Celestial park-n-ride• Close to home
(3-4 days)• Staging to:
– Moon– Sun-Earth L2– Mars– Asteroids – …
Sun-Earth L2
NGST TPF
Near Earth Near Earth AsteroidsAsteroids
MarMarss
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JSCGateway Operations – LTV Kickstage Disposal
• 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
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JSCPurpose
1. Identify concepts concerning the role of humans in libration point space missions
2. Examine mission design considerations for an Earth-Moon libration point (L1) gateway station
3. Assess delta-V (V) cost to retarget Earth-Moon L1 Gateway-bound LTV spacecraft kickstage to a selected disposal destination
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JSC
LTV KickstageDiverted to Disposal Destination
LTV Kickstage Disposal Options
Options considered for LTV kickstage disposal:1. Lunar Swingby to Heliocentric Orbit (HO)
2. Lunar Vertical Impact (LVI), typifies any lunar impact
3. Direct Return to Remote Ocean Area (DROA)
4. Lunar Swingby to Remote Ocean Area (SROA)
5. Transfer to Long Lifetime Geocentric Orbit (GO)
LTV/KickstageInjection Toward L1 LTV Crew Cab
Continues to L1
LTV / KickstageSeparation
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JSCMethodology• 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
• 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)
Lunar Orbit Inclination
51.6o
28.6o
80.2o
Earth Equator
Earth ParkingOrbit
Moon
Earth
L1(Between Earth
And Moon)
Maximum L1 ArrivalWedge Angle @ Libration
Point Arrival = 80.2o
Earth Equator
Lunar Orbit Inclination= 28.6o (max. ever)
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JSCMethodology (continued)
• HO, LVI, DROA, SROA, and GO maneuver times designed to minimize V for stage disposal subject to imposed constraints– Solutions considered to be a practical attempt to minimize these
maneuver Vs (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
* Developed and updated by Sam Wilson
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JSC
Earth Parking Orbit to Earth-Moon L1 V Cost vs. Flight Time
3500
4000
4500
5000
5500
6000
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Flight Time (hours)
To
tal
V
(m/s
),
Ea
rth
De
p.
+ L
1 A
rr.
E2LP-Based D ata
Arrival at Lunar Perigee
Arrival at Lunar Apogee
Initial Circ. Earth Parking Orbit Altitude = 407 km
Orbit Incl. Wrt Equator = 51.6o
Orbit Incl. wrt Earth-Moon Plane = 81o
Min. V @ 82 Hours = 4040 m/s
Min. V @ 100 Hours = 3940 m/s
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
1. Libration Point Transfer Vehicle (LTV) spacecraft with Kickstage in
initial 407 x 407 km parking orbit
L1
2. . Kickstage injects spacecraft& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performsmaneuver to achieve close
encounter with moon
6. Kickstage flies behind trailing limb of Moon to achieve geocentric C3>0 (hence departure from Earth-
Moon system) Moon
3. Coast phase;Kickstage jettison
Earth
5. Spacecraft arrivesat L1
Nominal crew vehicle trajectory to Earth-Moon L1-Trip time = 3.5 days (84 hours)- Braking maneuver at L1
84
3.5 day transfer3.5 day transfer
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JSCOption 1. Lunar Swing-By to Heliocentric Orbit (HO) Video
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JSCHeliocentric Orbit (HO) Transfer V vs. Libration Point Arrival Time
V Cost to Deflect LTV Kickstage from L1 Target to Heliocentric Orbit Via Lunar Swingby
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
Def
lec
tio
n
V
(m/s
)
Tra
nsfe
r O
rbit
Incl
inat
ion
w.r
.t. E
arth
-Moo
n P
lane
(de
g)
Heliocentric Orbit Achieved Via Lunar Orbit
V for Northerly Lunar LibrationPoint Arrival AzimuthV for Southerly Lunar Libration
Point Arrival Azimuth
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
Geocentric V-infinity > 800 m/s after Lunar Swingby
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
Moon atPerigee
Moon atApogee
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JSCOption 1. Lunar Swing-By to Heliocentric Orbit (HO)
• Advantages– No Earth or Lunar disposal issues (e.g., impact location, debris
footprint, litter)
– Relatively low disposal V cost
• Disadvantages– Heliocentric space litter (kickstage heliocentric orbit near that of
the earth)
– Periodic possibility of re-contact with Earth
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JSCOption 2. Lunar Vertical Impact (LVI)
1. Lunar Transfer Vehicle (LTV) spacecraft with Kickstage in
initial 407 x 407 km parking orbit
L1
2. Kickstage injects spacecraft& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performsmaneuver to achieve
lunar impact
6. Kickstage impactsLunar surface
Moon
3. Coast phaseKickstage jettison
Earth
5. Spacecraft arrivesat L1
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JSCOption 2. Lunar Vertical Impact (LVI)
Video
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JSCLunar Vertical Impact (LVI) Transfer V vs. Libration Point Arrival Time
V Cost to Deflect LTV Kickstage from L1 Target to Lunar Vertical Impact
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
Def
lect
ion
V
(m
/s)
V for Northerly Lunar LibrationPoint Arrival Azimuth
V for Southerly Lunar LibrationPoint Arrival Azimuth
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
Tra
nsfe
r O
rbit
Incl
inat
ion
w.r
.t. E
arth
-Moo
n P
lane
(de
g)Option 2. Lunar Vertical Impact (LVI)
Moon atPerigee
Moon atApogee
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JSCOption 2. Lunar Vertical Impact (LVI)
• Advantages– No Earth disposal issues (e.g., impact location, debris footprint,
litter, possible recontact)
• Disadvantage– Lunar litter
– Relatively high disposal V cost
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JSCOption 3. Direct Return to Remote Ocean Area (DROA)
1. Lunar Transfer Vehicle (LTV) spacecraft with Kickstage in
initial 407 x 407 km parking orbit
L1
2. Kickstage injects spacecraft& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performsmaneuver to achieve 20 atmospheric
entry angle and mid-ocean impact
5. Spacecraft arrivesat L1
6. Kickstage returns to Earth for ocean
impact
Moon
3. Coast phase;Kickstage jettison
Earth
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JSCOption 3. Direct Return to Remote Ocean Area (DROA) V Budget Gives 240o Longitude Control
• Entry flight path angle = -20o selected– Confines surface debris footprint
• Impact latitude is determined by:1. Spacecraft date of arrival at L1 and 2. Choice of northerly or southerly velocity azimuth at L1 arrival
• 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 V 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 V
budget must be sufficient to allow the impact point to be moved from its minimum-V location to an Atlantic or a Pacific mid-ocean line.
– At any latitude, the maximum longitude difference between the chosen mid-ocean lines is 240 degrees (see next chart).
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JSCOption 3. Direct Return to Remote Ocean Area (DROA)
Shaded Region Contains Max Longitude Difference (240o) Between Mid-Atlantic and Mid-Pacific Target Lines
x
x
x
x
x
x
xx
x
x
x x
x
x
x
x
x
x
x
xOcean Impact demo location
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JSCOption 3. Direct Return to Remote Ocean Area (DROA)
Video
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JSCDirect Remote Ocean Area (DROA) V vs. Libration Point Arrival TimeV Cost to Deflect LTV Kickstage from L1 Target to Remote Ocean Area Impact
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
De
flec
tio
n
V (
m/s
)
Upper Stage Disposal into Remote Ocean Area------------------------------------------------------------------
Direct entry (No Lunar Swing-by)20 deg Entry Flightpath Angle
240 deg Impact Longitude Spread
V for Northerly Lunar LibrationPoint Arrival Azimuth
V for Southerly Lunar LibrationPoint Arrival Azimuth
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
Tra
nsfe
r O
rbit
Incl
inat
ion
w.r
.t. E
arth
-Moo
n P
lane
(de
g)
Option 3. Direct Return to Remote Ocean Area (DROA)
Moon atPerigee
Moon atApogee
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JSCOption 3. Direct Return to Remote Ocean Area (DROA)
• 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 V 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
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JSCOption 4. Lunar Swingby to Remote Ocean Area (SROA)
1. Lunar Transfer Vehicle (LTV) spacecraft with Kickstage in
initial 407 x 407 km parking orbit
L1
2. Kickstage injects spacecraft& kickstage onto transfer
trajectory toward L1
4. Jettisoned kickstage performs maneuver to achieve close
encounter with moon
5. Spacecraft arrives at Earth-Moon L1
6. Kickstage passes in front of Moon’s leading limb and
returns to Earth for ocean impact
3. Coast phase;Kickstage jettison
28
JSCOption 4. Lunar Swingby to Remote Ocean Area (SROA)
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JSCSwing-by Remote Ocean Area (SROA) Transfer V vs. Libration Point Arrival TimeV Cost to Deflect LTV Kickstage from L1 Target to Remote Ocean Area Impact via Lunar Swing-by
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
Def
lec
tio
n
V*
(m
/s)
V for Northerly Lunar LibrationPoint Arrival Azimuth
V for Southerly Lunar LibrationPoint Arrival Azimuth
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
Tra
nsfe
r O
rbit
Incl
inat
ion
w.r
.t. E
arth
-Moo
n P
lane
(de
g)
* V represents lower bound
Option 4. Lunar Swingby to Remote Ocean Area (SROA)
Moon atPerigee
Moon atApogee
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JSCOption 4. Lunar Swingby to Remote Ocean Area (SROA)
• Advantages
– None identified
• Disadvantages– This option requires a greater V budget than any other one examined.
• The V values shown are minimum values for impact at an essentially random location.
• The V 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
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JSCOption 5. Transfer to Long Lifetime Geocentric Orbit (GO)
1. Lunar Transfer Vehicle (LTV) crew module with Kickstage in
initial 407 x 407 km parking orbit
2. Kickstage injects crew module& kickstage onto transfer
trajectory toward L1
4a. Jettisoned kickstage performsretargeted Earth parking orbit
maneuver
6. Kickstage continues on parking orbit
Moon
3. Coast phaseKickstage jettison
Earth
5. Crew module arrivesat L1
L1
4b. Alternatively, kickstage may raise perigee with maneuver at/near apogee of Earth-L1 transfer orbit
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JSCOption 5. Transfer to Long Lifetime Geocentric Orbit (GO) Video
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JSCGO V vs. Libration Point Arrival Time
Cost to Deflect LTV Kickstage from L1 Target to Long Lifetime Geocentric Orbit
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
Def
lec
tio
n
V
(m/s
)
V for Northerly Lunar LibrationPoint Arrival Azimuth
V for Southerly Lunar LibrationPoint Arrival Azimuth
Perigee: 6,600 km Apogee Range: 300,000 - 370,000 km
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
Tra
nsfe
r O
rbit
Incl
inat
ion
w.r
.t. E
arth
-Moo
n P
lane
(de
g)
Option 5. Transfer to Long Lifetime Geocentric Orbit (GO)
Moon atPerigee
Moon atApogee
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JSCOption 5. Transfer to Long Lifetime Geocentric Orbit (GO)
• Advantages– Preferable to deliberate ocean impact if kickstage carries hazardous material– In 4 of the 22 cases studied, the V 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 V 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 V.
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JSCHO, LVI, DROA, SROA, GO Transfer Delta-V vs. Libration Point Arrival Time
V Cost to Deflect LTV Kickstage from L1 Target to Disposal Destination
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
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)
De
fle
cti
on
V
(m
/s)
Key: N=North L1 Arrival Azimuth S=South L1 Arrival Azimuth
HO = Heliocentric OrbitLVI = Lunar Vertical ImpactDROA = Direct Remote Ocean AreaSROA = (Lunar) Swingby Remote Ocean AreaGO = Geocentric (Parking) Orbit
HO N
GO N
DROA N
LVI N
SROA N
HO S
GO S
DROA S
LVI S
SROA S
Moon atPerigee
Moon atApogee
Summary Results
JSC
Geocentric Orbit Lifetime Study
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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
Geocentric Orbit Lifetime
38
JSC
300000
300692
306456
313102
313767
320664
327826
328329
340036
342967
343636
351011
352551
359686
360952
6600
750015000
OrbitLifetime
(yrs)
Apogee (km)Perigee (km)
Lifetime for LTV Placed in Geocentric Orbit (GO)50
40
20
0
-16
LTV Orbit Lifetime
Note: A negative lifetime indicates LTV kickstage experienced either heliocentric departure from the Earth-Moon system or Lunar impact
Note: A negative lifetime indicates LTV kickstage experienced either heliocentric departure from the Earth-Moon system or Lunar impact
45 transfer orbits in sample space
39
JSCSummary
• Recommend Direct Remote Ocean Area impact disposal for cases without hazardous (e.g., radioactive) material on LTV kickstage– Controlled Earth contact
– Relatively small disposal V
– Avoids close encounter with Moon
– Trajectories can be very sensitive to initial conditions (at disposal maneuver)
• V 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 V cost
– Further study required to determine possibility of re-contact with Earth
JSC
Additional Slides
41
JSCSummary Results SWW:dmd
Earth-to-LL1 Transfer and Upper Stage Disposal DataAll 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
EarthArr Time RA Decl. Dist. Park Orbit Park Xfr Park Xfr(Nominal) 1000 RAN Epoch Orbit Orbit EOD LPA GO DROA HO SROA Orbit Orbit EOD LPA GO DROA HO SROA2006 Oct deg deg km 2006 Oct RANo iEMP MC MC MC MC MC OC OC OC RANo iEMP MC MC MC MC MC OC OC OC
10/6/06 4:00 -1.0 -0.1 304 10/2/06 16:00 -1.0 23.7 3061 782 52 50 87 88 66 106 178.9 81.0 3060 984 91 55 104 106 87 12410/7/06 4:00 12.4 7.2 304 10/3/06 16:00 6.7 24.0 3059 784 59 45 87 88 66 106 198.1 79.8 3061 980 91 55 105 106 88 12610/8/06 4:00 26.2 14.0 305 10/4/06 16:00 14.7 24.3 3060 781 61 42 87 88 65 111 217.7 75.9 3059 960 90 58 106 106 87 12810/9/06 8:00 42.9 20.7 309 10/5/06 20:00 25.0 28.7 3060 781 65 43 93 94 71 117 240.9 68.2 3059 916 87 55 107 108 87 13110/11/06 0:00 68.1 27.1 317 10/7/06 12:00 43.0 35.0 3063 776 63 53 101 101 78 126 273.2 54.4 3064 838 77 58 109 109 86 13210/12/06 8:00 88.5 28.7 324 10/8/06 20:00 61.2 44.0 3063 787 62 59 110 109 86 132 295.8 44.3 3063 786 61 62 110 109 87 13210/13/06 18:00 109.2 27.2 332 10/10/06 6:00 84.0 55.2 3066 810 59 61 115 115 92 135 314.5 35.9 3066 748 33 69 109 109 83 12910/15/06 18:00 135.4 20.7 339 10/12/06 6:00 117.6 69.2 3071 851 61 58 117 118 96 134 333.3 28.0 3070 726 7 83 107 107 83 12410/17/06 4:00 151.8 14.0 343 10/13/06 16:00 140.3 75.4 3072 875 63 53 116 117 95 132 343.4 24.9 3072 724 5 89 105 106 82 12010/18/06 12:00 166.2 6.9 344 10/15/06 0:00 160.7 78.7 3074 890 65 51 115 117 95 132 351.8 23.3 3073 727 10 92 104 105 82 12010/19/06 18:00 179.2 -0.1 345 10/16/06 6:00 179.3 80.1 3074 900 66 49 114 117 94 131 359.2 23.3 3073 733 11 93 104 106 81 121
RA RAN Right Ascension of Ascending Node RANo iEMPEODLPAGO Upper Stage Disposal in "Safe" Geocentric Orbit (6600 km Perigee Alt, 300000 - 370000 km Apogee Alt)DROALVIHOSROAOCMC
LVI: Use none on abort
Upper Stage Disposal in Remote Ocean Area (Direct,20 deg Atmospheric Entry Angle, 240 deg Longitude Spread)
Multi-Conic Trajectory
Upper Stage Disposal on Lunar Surface (Vertical Impact)Upper Stage Disposal in Heliocentric Orbit (via Lunar Swingby)
Overlapped Conic TrajectoryUpper Stage Disposal in Remote Ocean Area (via Lunar Swingby)
Inclination of Xfr Orbit wrt Earth-Moon PlaneRight Ascension of Ascending Node at RAN Epoch
LVIManeuver Delta-V, m/sManeuver Delta-V, m/s
Lunar L1
11-May-02
Libration Point Arrival (3.5 days after EOD)
Right Ascension
LVI
Northerly LL1 Arrival Azimuth Southerly LL1 Arrival Azimuth
Earth Orbit Departure to L1 Lunar Libration Point
42
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
Earth Moon L1 - Orbit Lifetime Study
43
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 keeping3. 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
Earth Moon L1 Study
44
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)
Earth-Moon L1 - Orbit LifetimeSpacecraft Initially at L1
45
JSCL1 Orbit Lifetime vs. EM L1 Position in Lunar Cycle
Orbit Lifetime and Earth-Moon L1 Distance vs. Days In a Lunar CycleBased on a free-drifting (uncontrolled) spacecraft with initial conditions at the Earth-Moon L1 point
0
20
40
60
80
100
120
0 4 8 12 16 20 24 28 32 36 40
Days
Orb
it L
ife
tim
e (
yrs
)
0
50000
100000
150000
200000
250000
300000
350000
Ea
rth
-Mo
on
L1
Dis
tan
ce
(k
m)
OrbitLifetime
Earth-Moon L1Distance
Moon atPerigee
Moon atApogee
Moon atPerigee
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)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)
46
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
EM L1 Orbit Lifetime w/ Delta-Vs
47
JSCOrbit Lifetime for Spacecraft at L1
Initial V of 10-500 m/s; 360o Range Relative to Initial Velocity
Lifetime Results For Satellite Starting at EM L1
2%
51%
44%
2%
1%
Earth Impact
Lunar
Heliocentric Departure
Earth Impact following Heliocentric Departure
100+ Years in Geocentric Orbit
48
JSCManeuver at Earth-Moon L1 (345,187 km apogee)V = 100 m/s Over 360o Range of Direction
0.618 Years
1.71 Years
100 Years
100 Years
L1 Velocity Direction
100 Years In
Earth Orbit
0.033 years
0.402 years
100 Years
Earth Impact
Lunar Impact
Escape to Heliocentric Orbit
49
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
EM L1 Orbit Lifetime – Future Work
50
JSCHuman Presence in Space
• Demonstrated benefit to human presence– Hubble Space
Telescope deploy and repair
– Retrieval of Long Duration Exposure Facility
– Retrieval of Westar and Palapa satellites
51
JSCLibration Point Missions
• 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– Human missions to extend human presence in space
52
JSC
Earth-Moon L1– No lunar departure
injection window
– Reusability
– Protection from failed station-keeping
– Specialized vehicle design
Lunar Mission: Libration Point vs. LOR
Lunar Orbit Rendezvous (LOR)
Shorter mission duration
Lower overall V cost
Fewer critical maneuvers required
Mission Scenario Advantages
53
JSCConsiderations for Human Lunar L1 Missions
• 18 year lunar inclination cycle
• Eccentricity of lunar orbit
• Performance cost versus time
• Frequency of outbound & inbound opportunities
54
JSC18 Year Lunar Inclination Cycle
Earth Equator
Lunar Orbit Inclination
Earth Equator
Lunar Orbit Inclination
Earth Equator
Lunar Orbit Inclination
Earth Equator
Lunar Orbit Inclination
55
JSC18 Year Lunar Inclination Cycle
Lunar OrbitInclination
51.6o 28.6o
23.0o
Earth Equator
Earth ParkingOrbit
Moon
Earth
L1(Between Earth
And Moon)
Minimum L1 ArrivalWedge Angle @ Libration
Point Arrival = 23o
Lunar Orbit Inclination
51.6o
28.6o
80.2o
Earth Equator
Earth ParkingOrbit
Moon
Earth
L1(Between Earth
And Moon)
Maximum L1 ArrivalWedge Angle @ Libration
Point Arrival = 80.2o
Earth Equator
Lunar Orbit Inclination
56
JSCEccentricity of Lunar Orbit
Earth Parking Orbit to Earth-Moon L1 V Cost vs. Flight Time
3000
4000
5000
6000
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Flight Time (hours)
To
tal
V
(m/s
)
E2LP-Based Data
Arrival at Lunar Perigee
Arrival at Lunar Apogee
Initial Circ. Earth Parking Orbit Altitude = 407 km
Orbit Incl. Wrt Equator = 51.6o
Orbit Incl. wrt Earth-Moon Plane = 28.15o
57
JSCPerformance Cost vs. Time
Earth Parking Orbit to Earth-Moon L1 V Cost vs. Flight Time
0
1000
2000
3000
4000
5000
6000
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Flight Time (hours)
V
(m
/s)
E2LP-Based Data
Earth Orbit Departure (EOD)
EOD + LPA
EOD+LPA+Libration Point Dep.
Libration Point Arrival (LPA)
Initial Circ. Earth Parking Orbit Altitude = 407 km
Orbit Incl. Wrt Equator = 51.6o
Orbit Incl. wrt Earth-Moon Plane = 28.15o
58
JSCFrequency of Outbound and Inbound Opportunities
EO H=407.00,I=51.60,RAN=0.00 @ 2009 Jan 09\00:00
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
EOD/EOA Time, days since 2009 Jan 09\00:00
LPA
/LP
D T
ime,
da
ys s
ince
200
9 J
an 0
9\00
:00
EARTH-MOON L1 MISSION OPPORTUNITIESCoplanar Depart From / Return To ISS
OUTBOUND TRAJECTORIES TO EARTH-MOON L1
INBOUND TRAJECTORIES FROM
EARTH-MOON L1
Arrival-time position of L1 lies in the departure-
time ISS orbit plane
Arrival-time position of L1 lies in the departure-
time ISS orbit plane
Departure-time position of L1 lies in the arrival-time ISS
orbit plane
Departure-time position of L1 lies in the arrival-time ISS
orbit plane
164 Hours
82 Hours
164 Hours82 Hours
328 Hours328 Hours
Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)
Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)
EOD/EOA Time, days since 2009 Jan 09\00:00
LP
A/L
PD
Tim
e, d
ay
s s
inc
e 2
00
9 J
an
09
\00
:00
KEYEOD = Earth orbit departureEOA = Earth orbit arrivalLPA = Libration point arrivalLPD = Libration point departure
EO H=407.00,I=51.60,RAN=0.00 @ 2009 Jan 09\00:00
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
EOD/EOA Time, days since 2009 Jan 09\00:00
LPA
/LP
D T
ime,
da
ys s
ince
200
9 J
an 0
9\00
:00
EARTH-MOON L1 MISSION OPPORTUNITIESCoplanar Depart From / Return To ISS
OUTBOUND TRAJECTORIES TO EARTH-MOON L1
INBOUND TRAJECTORIES FROM
EARTH-MOON L1
Arrival-time position of L1 lies in the departure-
time ISS orbit plane
Arrival-time position of L1 lies in the departure-
time ISS orbit plane
Departure-time position of L1 lies in the arrival-time ISS
orbit plane
Departure-time position of L1 lies in the arrival-time ISS
orbit plane
164 Hours
82 Hours
164 Hours82 Hours
328 Hours328 Hours
Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)
Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)
Earth-to-L1 Opportunity (82 hr. transfer)L1-to-Earth Opportunity (82 hr. transfer)
EOD/EOA Time, days since 2009 Jan 09\00:00
LP
A/L
PD
Tim
e, d
ay
s s
inc
e 2
00
9 J
an
09
\00
:00
KEYEOD = Earth orbit departureEOA = Earth orbit arrivalLPA = Libration point arrivalLPD = Libration point departure
59
JSCFrequency of Outbound and Inbound Opportunities
60
JSC
61
JSCTotal Transfer V vs LPA Time
Total Transfer Delta-V vs. Libration Point Arrival TimeTotal transfer V = EOD V + LPA V; LPA Plane Change = 80.2o
3750
3800
3850
3900
3950
4000
4050
10/6/20060:00
10/8/20060:00
10/10/20060:00
10/12/20060:00
10/14/20060:00
10/16/20060:00
10/18/20060:00
10/20/20060:00
Libration Point Arrival Time (mm/dd/yy hh:mm)
To
tal T
ran
sfe
r D
elt
a-V
(m
/s)
Northerly Lunar Libration Point Arrival Azimuth
Southerly Lunar Libration Point Arrival Azimuth
62
JSCTransfer V vs LPA TimeTransfer Delta-V vs. Libration Point Arrival Time
Total transfer V = EOD V + LPA V 3.5 Day Trip Time
0
500
1000
1500
2000
2500
3000
3500
4000
10/6/20060:00
10/8/20060:00
10/10/20060:00
10/12/20060:00
10/14/20060:00
10/16/20060:00
10/18/20060:00
10/20/20060:00
Libration Point Arrival Time (mm/dd/yy hh:mm)
Tra
ns
fer
De
lta
-V
(m/s
) Earth Parking Orbit DepartureNortherly and Southerly Lunar Libration Point Arrival Azimuth
Libration Point Arrival VSoutherly Lunar Libration Point Arrival Azimuth
Total Transfer VNortherly Lunar Libration Point Arrival Azimuth
Total Transfer VSoutherly Lunar Libration Point Arrival
Azimuth
Libration Point Arrival VNortherly Lunar Libration Point Arrival Azimuth