condon

Document Sample
condon Powered By Docstoc
					                                                                                                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
                                                                                                 1
                                 S. Wilson, Elgin Software, Inc.
                                               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                                     g
                                                             icin
                                                         erv
  mission objectives                         le sco
                                                    pe s
                                                                                   Sun-
                                                                                   Sun-
                                        o te                                       Earth
                                    ns t
• Closed-end missions          Hum
                                   a                                             Libration
                                                                                   Points

                                              Humans to L1


                                               Humans
                                                      to Moon         Earth-
                                                                      Earth-                     The
                                                                       Moon                      Moon
                        Earth Orbit                                  Libration
                        Operations
       Examples                                                        Points
                                                     Hu
        Apollo                                          m
                                                            an
                                                              st
        Skylab                                                  oM
                                                                     ar
        Apollo-Soyuz Test                                               s           Near Earth
           Project                                                                   Asteroids
        Columbus’ voyage of                                                  Mars
           discovery to the
                                                                Mars Orbit           Phobos /
           new world                                                                 Deimos

                                                                                                  5
          Expeditionary vs. Evolutionary JSC
• Ongoing missions
• Open-end missions on which
  other missions can build                                                             Sun-
                                                                                       Sun-
                                                                                       Earth
• Greater initial capital investment                                                 Libration
                                                                                       Points

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


                                                            Earth-
                                                            Earth-                               The
                                                             Moon
                        Earth Orbit                        Libration                             Moon
                        Operations                           Points

Examples
 International Space Station program                                                      Near Earth
                                                                                            Asteroids
 Voyages of Prince Henry the Navigator
  of Portugal                                                                       Mars
     The man chiefly responsible for
                                                                       Mars Orbit          Phobos /
       Portugal’s age of exploration                                                       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                                        NGST
    –   …                              Mars              TPF
                                                         Sun-Earth L2
                                  Near Earth
                                   Asteroids                     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                              JSC

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 (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            LTV / Kickstage
Injection Toward L1           Separation                  LTV Crew Cab
                                                         Continues to L1



                                                       LTV Kickstage
                                              Diverted to Disposal Destination


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)
                                                                       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                 Lunar Orbit Inclination
                                                 Orbit         Earth
                   Lunar Orbit Inclination
                     = 28.6o (max. ever)                        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)                                                                                              JSC
E2L P-Based D ata


                                                Earth Parking Orbit to Earth-Moon L1 DV Cost vs. Flight Time
                                                                                                                                                                   6. Kickstage flies behind trailing
                            6000                                                                                                                                          limb of Moon to achieve
                                                                                           Initial Circ. Earth Parking Orbit Altitu de = 407 km
                                                                                                                                                                          geocentric C3>0 (hence
Total DV (m/s), Earth Dep. + L1 Arr.




                                                                                                                         o
                                                                                           Orbit Incl. Wrt Equ ator = 51.6
                                                                                                                                   o
                                                                                           Orbit In cl. wrt Earth-Mo on Plan e = 81
                            5500                                                                                                                                            departure from Earth-
                                                                                                                                                                               Moon system)                     Moon
                                                                          Arrival at Lun ar
                            5000                                              Apo gee
                                                                                                         3.5 day transfer
                                            Arrival at Lun ar
                                                Perigee
                            4500
                                                                                       Min. DV @ 82 Hours = 4040 m/ s
                                                                                                                                                                                              L1
                            4000                                                                                                                                                        5. Spacecraft arrives
                                                                                                                                                                                               at L1
                                                                                                        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)


                                                              1. Libration Point Transfer Vehicle (LTV)                                                                  Nominal crew vehicle trajectory to
                                                                    spacecraft with Kickstage in                                                                         Earth-Moon L1
                                                                  initial 407 x 407 km parking orbit                                                                     -Trip time = 3.5 days (84 hours)
                                                                                                                                                                         - Braking maneuver at L1




                                                                                                    Earth
                                                                                                                                                       4. Jettisoned kickstage performs
                                                                                                                                                           maneuver to achieve close
                                                                                                                                                             encounter with moon

                                            2. . Kickstage injects spacecraft                                                  3. Coast phase;
                                                 & kickstage onto transfer                                                    Kickstage jettison
                                                                                                                                                                                                          13
                                                    trajectory toward L1
Option 1. Lunar Swing-By to Heliocentric Orbit (HO)
                      Video                           JSC




                                                      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
                                                                                         Moon at                                                                                                 Moon at
                                                                                         Perigee                                                                                                 Apogee
                                                                                 130

                                                                                 120
                      Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)




                                                                                 110                                                                       DV for Northerly Lunar Libration
                                                                                       DV for Southerly Lunar Libration                                         Point Arrival Azimuth
                                                                                 100
                                                                                            Point Arrival Azimuth
Deflection DV (m/s)




                                                                                 90

                                                                                 80

                                                                                 70

                                                                                 60

                                                                                 50

                                                                                 40

                                                                                 30

                                                                                 20      Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)   Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                              Northerly Lunar Libration Point Arrival Azimuth            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)                  JSC
• 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
                                                 4. Jettisoned kickstage performs
                                                       maneuver to achieve
                                                            lunar impact

2. Kickstage injects spacecraft      3. Coast phase
   & kickstage onto transfer        Kickstage jettison
      trajectory toward L1
                                                                                                       17
Option 2. Lunar Vertical Impact (LVI)
               Video                    JSC




                                        18
                                                                                         Option 2. Lunar Vertical Impact (LVI)                                                                               JSC
                                                                                                    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

                                                                                 130                                                                       DV for Northerly Lunar Libration
                                                                                                                                                                Point Arrival Azimuth
                                                                                 120
                      Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)




                                                                                 110

                                                                                 100
                                                                                                                                                            DV for Southerly Lunar Libration
                                                                                                                                                                 Point Arrival Azimuth
Deflection DV (m/s)




                                                                                 90

                                                                                 80

                                                                                 70

                                                                                 60

                                                                                 50

                                                                                 40

                                                                                 30

                                                                                 20
                                                                                       Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)   Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                            Northerly Lunar Libration Point Arrival Azimuth            Southerly Lunar Libration Point Arrival Azimuth
                                                                                 10
                                                                                        Moon at                                                                                                Moon at
                                                                                  0     Perigee                                                                                                Apogee

                                                    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)                                      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)                                         JSC

                                                                   5. Spacecraft arrives                 Moon
                                                                          at L1


                                                                                       L1



            1. Lunar Transfer Vehicle (LTV)
              spacecraft with Kickstage in
           initial 407 x 407 km parking orbit                                     6.       Kickstage returns to
                                                                                             Earth for ocean
                                                                                                 impact



                          Earth
                                                  4. Jettisoned kickstage performs
                                                maneuver to achieve 20 atmospheric
                                                 entry angle and mid-ocean impact

2. Kickstage injects spacecraft    3. Coast phase;
   & kickstage onto transfer      Kickstage jettison
      trajectory toward L1

                                                                                                         21
        Option 3. Direct Return to Remote Ocean Area (DROA)
                   DV Budget Gives 240o Longitude Control                                          JSC
•   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 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 mid-
          ocean 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                        JSC




                                                      24
                                                                                          Option 3. Direct Return to Remote Ocean Area (DROA)                                                                                    JSC
                                                                                              Direct Remote Ocean Area (DROA) DV vs. Libration Point Arrival Time
                                                                                                DV Cost to Deflect LTV Kickstage from L1 Target to Remote Ocean Area Impact
                                                                                 140      Moon at                                                                                                                      Moon at
                                                                                          Perigee                                                                                                                      Apogee
                                                                                 130

                                                                                 120
                      Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)




                                                                                                              Upper Stage Disposal into Remote Ocean Area
                                                                                 110
                                                                                                              ------------------------------------------------------------------
                                                                                                                                                                                    DV for Southerly Lunar Libration
                                                                                                                        Direct entry (No Lunar Swing-by)
                                                                                 100                                                                                                     Point Arrival Azimuth
                                                                                                                          20 deg Entry Flightpath Angle
                                                                                                                       240 deg Impact Longitude Spread
Deflection DV (m/s)




                                                                                  90

                                                                                  80

                                                                                  70

                                                                                  60

                                                                                  50

                                                                                  40                                                                                                 DV for Northerly Lunar Libration
                                                                                                                                                                                          Point Arrival Azimuth
                                                                                  30

                                                                                  20   Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)                             Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                            Northerly Lunar Libration Point Arrival Azimuth                                      Southerly Lunar Libration Point Arrival Azimuth
                                                                                  10

                                                                                   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.    Kickstage passes in
                                                                                    front of Moon’s
  1. Lunar Transfer Vehicle (LTV)
                                                                                   leading limb and
    spacecraft with Kickstage in
                                                                                  returns to Earth for
 initial 407 x 407 km parking orbit
                                                                                      ocean impact




                                                   4. Jettisoned kickstage performs
                                                       maneuver to achieve close
                                                         encounter with moon

2. Kickstage injects spacecraft        3. Coast phase;
   & kickstage onto transfer          Kickstage jettison
      trajectory toward L1
                                                                                                         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

                                                                                  130

                                                                                  120
                       Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)




                                                                                  110                                                                          DV for Southerly Lunar Libration
                                                                                                                                                                    Point Arrival Azimuth
                                                                                  100
                                                                                        DV for Northerly Lunar Libration
Deflection DV* (m/s)




                                                                                   90        Point Arrival Azimuth

                                                                                   80

                                                                                   70

                                                                                   60

                                                                                   50

                                                                                   40

                                                                                   30

                                                                                   20
                                                                                        Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)     Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                             Northerly Lunar Libration Point Arrival Azimuth              Southerly Lunar Libration Point Arrival Azimuth
                                                                                   10
                                                                                           Moon at                                                                                              Moon at
                                                                                    0      Perigee                                                                                              Apogee

                                                                        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)                                      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.    Kickstage
                                                                                                 continues on
                                                                                                 parking orbit




                               Earth                    4a. Jettisoned kickstage performs
                                                          retargeted Earth parking orbit
                                                                       maneuver


                                               3. Coast phase
                                              Kickstage jettison
2. Kickstage injects crew module
    & kickstage onto transfer
       trajectory toward L1
                                                                                                             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       Moon at                                                                                            Moon at
                                                                                           Perigee                                                                                            Apogee
                                                                                 130
                      Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)




                                                                                 120
                                                                                                                                                                 Perigee: 6,600 km
                                                                                 110                                                                             Apogee Range: 300,000 - 370,000 km
                                                                                        DV for Southerly Lunar Libration
                                                                                 100         Point Arrival Azimuth
Deflection DV (m/s)




                                                                                  90                                                                Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                                                                                         Northerly Lunar Libration Point Arrival Azimuth
                                                                                  80

                                                                                  70

                                                                                  60
                                                                                                                                                                DV for Northerly Lunar Libration
                                                                                  50
                                                                                                                                                                     Point Arrival Azimuth
                                                                                  40

                                                                                  30

                                                                                  20
                                                                                       Transfer Orbit Inclination w.r.t. Earth-Moon Plane (deg)
                                                                                  10        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                                                           JSC
                                        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
                              Moon at                                                                               Moon at
                      140     Perigee                                                                               Apogee

                      130                                                                                                     SROA N

                      120                                                                                                     SROA S
                                                                                                                               LVI N
                      110
                                                                                                                                LVI S
                      100
                                                                                                                               HO N
                                                                                                                              DROA S
Deflection DV (m/s)




                       90

                       80                                                                                                       HO S

                       70
                                                                                                                                GO N
                       60

                       50
                                                                                                                              DROA N
                       40
                             Key:   N=North L1 Arrival Azimuth
                                    S=South L1 Arrival Azimuth
                       30
                             HO     =   Heliocentric Orbit
                       20    LVI    =   Lunar Vertical Impact
                             DROA   =   Direct Remote Ocean Area
                       10    SROA   =   (Lunar) Swingby Remote Ocean Area                                                       GO S
                             GO     =   Geocentric (Parking) Orbit
                         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
                                                                                                                              35
                                                     Libration Point Arrival Time (mm/dd/yy   hh:mm)
                                  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
                                                                                                                                                    35

                                                                                                                                                              09
                                                                                                                                                        96
                                                                                                                                              35




                                                                                                                                                                  52
                                                                                                                                                         86
                                                                                                                                               25
                                                                                                                                     35


                                                                                                                                                   51
                                                                                                                                         10
                                                                                                                               34


                                                                                                                                          11
                                                                                                                                36
                                                                                                                      34



                                                                                                                                    36
                                                                                                                          29
                                                                                                                34



                                                                                                                           67
                                                                                                                 00
                                                                                                       32



                                                                                                                     36
                                                                                                           83
                                                                                                 32




                                                                                                                                              Note: A negative lifetime
                                                                                                            29
                                                                                                  78
                                                                                       32



                                                                                                      26
                                                                                        06
                                                                             31




                 15000                                                                                                                        indicates LTV kickstage
                                                                                            64
                                                                              37
                                                                   31




                   7500                                                                                          Apogee (km)
                                                                                  67




                                                                                                                                              experienced either heliocentric
                                                                    31
                                                         30




    Perigee (km)
                                                                        02




                     6600
                                                          64
                                               30




                                                                                                                                              departure from the Earth-Moon
                                                              56
                                                06
                                     30




                                                    92




                                                                                                                                              system or Lunar impact
                                      00
                                          00




                                                                                                                                                                                         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

                 Lunar L1                             Earth                   Northerly LL1 Arrival Azimuth                                        Southerly LL1 Arrival Azimuth
     Arr Time         RA      Decl.    Dist.       Park Orbit     Park   Xfr             Maneuver Delta-V, m/s                       Park   Xfr               Maneuver Delta-V, m/s
    (Nominal)                          1000       RAN Epoch       Orbit Orbit EOD LPA GO DROA             LVI  HO           SROA     Orbit Orbit EOD LPA GO DROA              LVI     HO SROA
     2006 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      87 124
10/7/06 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      88 126
10/8/06 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      87 128
10/9/06 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      87 131
10/11/06 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      86 132
10/12/06 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      87 132
10/13/06 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      83 129
10/15/06 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      83 124
10/17/06 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      82 120
10/18/06 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      82 120
10/19/06 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        Right Ascension
                   RAN       Right Ascension of Ascending Node
                   RANo      Right Ascension of Ascending Node at RAN Epoch
                   iEMP      Inclination of Xfr Orbit wrt Earth-Moon Plane
                   EOD       Earth Orbit Departure to L1 Lunar Libration Point
                   LPA       Libration Point Arrival (3.5 days after EOD)
                   GO        Upper Stage Disposal in "Safe" Geocentric Orbit (6600 km Perigee Alt, 300000 - 370000 km Apogee Alt)
                   DROA      Upper Stage Disposal in Remote Ocean Area (Direct,20 deg Atmospheric Entry Angle, 240 deg Longitude Spread)
                   LVI       Upper Stage Disposal on Lunar Surface (Vertical Impact)
                   HO        Upper Stage Disposal in Heliocentric Orbit (via Lunar Swingby)
                   SROA      Upper Stage Disposal in Remote Ocean Area (via Lunar Swingby)
                   OC        Overlapped Conic Trajectory
                   MC        Multi-Conic Trajectory




                                                                                                                                                                               41
                   LVI: Use none on abort
   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                                             Moon at                                       Moon at
                                                   Perigee                                             Apogee                                        Perigee
                                                                                                                                                               300000
                       100
                                 Orbit
                                 Lifetime
                                 Earth-
                                 Moon L1                                                                                                                       250000




                                                                                                                                                                        Earth-Moon L1 Distance (km)
                        80       Distance
Orbit Lifetime (yrs)




                                                                                                                                                               200000

                        60

                                                                                                                                                               150000


                        40
                                       Orbit lifetimes <100 years result in either lunar impact or heliocentric trajectory (via lunar fly-by)                  100000
                                       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
     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          1%
                                    2%       2% Earth Impact
       Earth Impact following
       Heliocentric Departure




               44%
   Heliocentric                                                         51%
    Departure
                                                                          Lunar




                                                                                  47
            Maneuver at Earth-Moon L1 (345,187 km apogee)
                  DV = 100 m/s Over 360o Range of Direction                   JSC
                                                  100 Years

                                      100 Years                  1.71 Years




                               0.033 years
                                                                            100 Years
            L1 Velocity
                                                                            In Earth
             Direction                                                        Orbit




Earth Impact
                                    0.618 Years                 100 Years
Lunar Impact                                      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              Lunar Orbit
– No lunar departure       Rendezvous (LOR)
  injection window          Shorter mission
– Reusability               duration
– Protection from failed    Lower overall DV cost
  station-keeping           Fewer critical
– Specialized vehicle       maneuvers required
  design
                                              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
                                          (Between Earth                         23.0o
                                            And Moon)
                                                                                      Lunar Orbit
                                                           Earth                      Inclination
           Lunar Orbit Inclination                                            28.6o
                                                                   51.6o
                                                                                      Earth Equator
  Earth Equator
                                                            Moon
                                                                       Minimum L1 Arrival
                                                                     Wedge Angle @ Libration
                                                                        Point Arrival = 23o
                                       Earth Parking
                                           Orbit


                                                    Maximum L1 Arrival
                                                  Wedge Angle @ Libration
                                                    Point Arrival = 80.2o

                                     Earth Parking                 Lunar Orbit Inclination
                                         Orbit             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
                                                                        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
Total D V (m/s)




                                                           Arrival at Lunar
                                                               Apogee



                                   Arrival at Lunar
                  4000                 Perigee




                  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
E2LP-Based Data


                       Earth Parking Orbit to Earth-Moon L1 D V Cost vs. Flight Time
                                                       Initial Circ. Earth Parking Orbit Altitude = 407 km
                                                                                        o
            6000                                       Orbit Incl. Wrt Equator = 51.6
                                                                                                  o
                                                       Orbit Incl. wrt Earth-Moon Plane = 28.15
            5000
                                                                               EOD+LPA+Libration Point Dep.
            4000
                                                                                                  EOD + LPA
D V (m/s)




            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
                                                                                                                                                                                                 s
                                                                                                                                                                                               ur o ur sur s
                                                                                EO H=407.00,I=51.60,RAN=0.00 @ 2009 Jan 09\00:00                                                            Ho        o
                                                                                                                                                                                          8      4H H        rs
                                                  140
                                                                                                                                                                                        32    16 82 Houur s
                                                                                                                                                                                                    82 Ho r s
                                                                                                                                                                                                       4
                                                               OUTBOUND                              Earth-to-L1 Opportunity
                                                                                                     Earth-to-L1 Opportunity           (82 hr. transfer)
                                                                                                                                        (82 hr. transfer)                                           16 Ho u
                                                                                                                                                                                                       8
                                                            TRAJECTORIES TO                          L1-to-Earth Opportunity
                                                                                                     L1-to-Earth Opportunity           (82 hr. transfer)
                                                                                                                                        (82 hr. transfer)                                           32

                                                  120        EARTH-MOON L1
     LPA/LPD Time, days since 2009 Jan 09\00:00




                                                            Arrival-time position of
                                                             Arrival-time position of
LPA/LPD Time, days since 2009 Jan09\00:00




                                                            L1 lies in the departure-
                                                            L1 lies in the departure-                                                          e
                                                  100         time ISS orbit plane                                                        im
                                                               time ISS orbit plane
                                                                                                                                       tT
                                                                                                                                  gh
                                                                                                                            d F li                                                      KEY
                                                                                                                       un                                          e
                                                                                                                                                              T im
                                                                                                                                                                             EOD = Earth orbit departure
                                                  80
                                                                                                              tb   o                                      t                  EOA = Earth orbit arrival
                                                                                                           Ou                                        gh
                                                                                                                                                 F li
                                                                                                                                                                             LPA = Libration point arrival
                                                                                                     n   t
                                                                                                ta                                          nd
                                                                                                                                                                             LPD = Libration point
                                                                                             ns                                         u                                    departure
                                                  60
                                                                                        Co                                      In   bo
                                                                                                                            t
                                                                                                                        tan                                               Departure-time
                                                                                                                                                                          Departure-time
                                                                                                                ns                                                     position of L1 lies in
                                                  40                                                         Co                                                        position of L1 lies in
                                                                                                                                                                       the arrival-time ISS
                                                                                                                                                                        the arrival-time ISS
                                                                                                                                                                            orbit plane
                                                                                                                                                                            orbit plane

                                                  20
                                                                                                                                                                               INBOUND
                                                                                                                                                                          TRAJECTORIES FROM
                                                                                                                                                                            EARTH-MOON L1
                                                   0
                                                        0             20                40                    60                       80                     100              120                140
                                                                                              EOD/EOA Time, days since 2009 Jan 09\00:00
                                                                                              EOD/EOA Time, days since 2009 Jan 09\00:00                                                                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



                               4000                                              Northerly Lunar Libration Point Arrival Azimuth
Total Transfer Delta-V (m/s)




                               3950



                               3900



                               3850



                               3800

                                                                                 Southerly Lunar Libration Point Arrival Azimuth

                               3750
                                 10/6/2006     10/8/2006   10/10/2006   10/12/2006   10/14/2006      10/16/2006   10/18/2006   10/20/2006
                                   0:00          0:00         0:00         0:00         0:00            0:00         0:00         0:00
                                                            Libration Point Arrival Time (mm/dd/yy    hh:mm)                       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

                                              Total Transfer DV                                                         Total Transfer DV
                         3500   Northerly Lunar Libration Point Arrival Azimuth                               Southerly Lunar Libration Point Arrival
                                                                                                                            Azimuth

                         3000
                                                                            Earth Parking Orbit Departure
Transfer Delta-V (m/s)




                                                             Northerly and Southerly Lunar Libration Point Arrival Azimuth

                         2500


                         2000


                         1500
                                           Libration Point Arrival DV
                                                                                                                  Libration Point Arrival DV
                                Southerly Lunar Libration Point Arrival Azimuth
                                                                                                       Northerly Lunar Libration Point Arrival Azimuth
                         1000


                         500


                            0
                          10/6/2006       10/8/2006        10/10/2006       10/12/2006        10/14/2006       10/16/2006        10/18/2006        10/20/2006
                             0:00           0:00              0:00             0:00              0:00             0:00              0:00              0:00
                                                            Libration Point Arrival Time (mm/dd/yy               hh:mm)                                  62

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:5
posted:12/28/2010
language:English
pages:62