jsc 1 earth moon libration point (l1) gateway station – libration point transfer vehicle kickstage...

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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, [email protected]. 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.

3

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


Humans to Moon

Humans to L1

Humans to telescope servicing

Humans to Mars

The The MoonMoon


SunSun--Earth Earth



Mars Orbit

MarsMars




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


SunSun--Earth Earth



Mars Orbit

MarsMars



Humans (to L1, Moon, Telescope Servicing, and Mars)


The The MoonMoon


SunSun--Earth Earth



Mars Orbit

MarsMars



Humans (to L1, Moon, Telescope Servicing, and Mars)


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


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

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Libration Point Arrival Time (mm/dd/yy hh:mm)

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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


L1

2. Kickstage injects spacecraft& kickstage onto transfer


4. Jettisoned kickstage performsmaneuver to achieve

lunar impact

6. Kickstage impactsLunar surface

Moon

3. Coast phaseKickstage jettison

Earth


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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

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Def

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V for Northerly Lunar LibrationPoint Arrival Azimuth

V for Southerly Lunar LibrationPoint Arrival Azimuth



Tra

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(de

g)Option 2. Lunar Vertical Impact (LVI)

Moon atPerigee

Moon atApogee

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• 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)



L1



4. Jettisoned kickstage performsmaneuver to achieve 20 atmospheric

entry angle and mid-ocean impact


6. Kickstage returns to Earth for ocean

impact

Moon


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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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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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

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De

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)

Upper Stage Disposal into Remote Ocean Area------------------------------------------------------------------

Direct entry (No Lunar Swing-by)20 deg Entry Flightpath Angle

240 deg Impact Longitude Spread





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Option 3. Direct Return to Remote Ocean Area (DROA)

Moon atPerigee

Moon atApogee

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• 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)



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


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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

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* V represents lower bound

Option 4. Lunar Swingby to Remote Ocean Area (SROA)

Moon atPerigee

Moon atApogee

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• 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


2. Kickstage injects crew module& kickstage onto transfer


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

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Perigee: 6,600 km Apogee Range: 300,000 - 370,000 km



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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

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De

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(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

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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

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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

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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

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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

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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

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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


Earth Equator


Earth Equator


Earth Equator


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


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


56

JSCEccentricity of Lunar Orbit


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



Orbit Incl. wrt Earth-Moon Plane = 28.15o

57

JSCPerformance Cost vs. 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)



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



Departure-time position of L1 lies in the arrival-time ISS

orbit plane


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)



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


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






orbit plane


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)



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


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


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

jsc 1 earth moon libration point (l1) gateway station – libration point transfer vehicle kickstage...

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